Honda 250-305s… The Rules

Honda churned out somewhere around 250,000 of the 1960-67 250-305cc twins. 60+ years later, they still turn up from the back of someone’s garage or at a swap meets, etc.; and people have questions! Because of the depth of changes within each of the three models: Dream, Scrambler and Super Hawk, I can only skim the top of the subject,  but hopefully this story will help to defuse some of the confusion about these classic machines.

Rule #1

They are NOT all the same. There are “early” and “late” Dreams, Scramblers and Super Hawks with changes that are external and internal. Always use the serial numbers for reference when seeking parts or just asking for help. For the most part, the overall engine and tuning specifications are quite similar within each model, but there are deviations that can be important if you are going in deep on a repair or restoration.

Rule #2

Like cars of the era, these are battery-powered motorcycles. While the permanent magnet charging systems can generate sufficient spark to get an engine started, they really need a fully-charged battery and functioning charging system to operate normally. If you jump start any of these bikes and then let the charging system wrestle with a dead/dying battery the charging system will pump out as much as 40volts AC into the 12v electrical system blowing up all the light bulbs and often damaging the rectifiers. 

Because of changes in the 12N9-3A batteries used in CB72-77 and later model CA77 Dreams, you MUST look for the ones with the extended posts, not the ones with small vertical posts. There are TWO different batteries used on the Dreams. They DO NOT interchange and the correct one must be used to match up with the different battery box, tool tray, battery ground and side cover options for each type.

Rule #3

Because of poor storage or neglect, the engines are often found to be seized solidly. Moisture build up inside the cylinders will cause water to corrode the cylinder walls and piston rings into the ring lands. Depending upon just how badly seized it is, using a penetrating oil to help unstick the pistons can be successful in allowing rotation of the crankshaft again. Some people have been successful in getting these engines running again, but usually the cylinder bores are damaged, causing further damage to the pistons/rings.

Invariably the piston rings are stuck in the piston ring lands and are unable to do their normal function of sealing up against the cylinder walls. Because the piston clearances are so small  (often just one or two thousandths of an inch), the engines appear to have compression and will run. The corrosion is generally so severe that even running the engines for hours will not release the rings from the pistons for normal operation. Eventually, the lack of piston ring control and damage to the cylinder walls causes blowby and exhaust smoke. 

Excess oil in the cylinders will foul the spark plugs and eventually use up the 1.5liters of oil that the engines depend upon for normal operation. Plan on re-boring the cylinders and replacing the pistons and rings, at the very least. OEM pistons are increasingly hard to find and when you do the prices are beyond silly ($200 each). CB and CA pistons can be swapped into other engines, with only a slight change in compression readings.  Early Dream pistons had thick 2mm rings, but eventually were superseded by a version using thinner 1.5mm CB rings. https://classichondarestoration.com has forged piston kits available as replacements for the cast OEM pistons.

Rule #4

Clean the centrifugal oil filter! Depending on the year of production, cleaning the filter may or may not require removal of the whole clutch cover. Later “big hole” clutch covers facilitate filter removal and replacement without cover removal, but it is a bit tricky to accomplish. The spinning oil filter is driven by a small crankshaft sprocket-driven chain. There is a thrust washer on the shaft that must be placed on the outside of the filter to prevent the locating pin from gouging the outer cover.  There is a small o-ring that seals the cover to the filter body. Replace the o-ring if damaged. They can often be reused if installed correctly. The filter body must be thoroughly cleaned, along with the inside of the cover. Any leftover scraps will go directly into the crankshaft bearings, so be diligent in your cleaning efforts.

In proper working order, these engines use very little oil, but some will be burned in normal operation. Make sure that the crankcases are filled to the top mark on the dipstick before riding out for any distance. These engines do not have valve stem seals; however a clever air bleed system on the intake valve guides helps to lessen the oil consumption past the valve stems.  Honda’s GN4 10-30 oil is more than sufficient for normal operating conditions. 

When these engines were originally built, oil technology was in its infancy in many respects. Honda specified non-detergent oils originally, counting on regular oil changes to keep the engine clean inside. The problem with non-detergent oils is that they don’t help suspend particles in the oil like today’s detergent oils do successfully. 

It isn’t a bad idea to pull down the oil pump to check the screen for damage and for the presence of thick, mucky oil deposits and contaminants. Virtually every engine I have torn down has had a thick layer of deposits lying in the bottom of the engine cases. Even with detergent oils, when these engines sit for years unused, the suspended contaminants eventually fall out of suspension and wind up in the bottom of the engine.

Rule #5

ALWAYS ensure that the engine spark timing/advance is set properly. Check the timing with the engine running, using a dynamic timing light. Static spark timing is fine to get the engine running, but you must check it with the timing light when the engine is running to prevent piston seizures and help smooth out idling speed problems and carburetion setting issues. The spark advancer system is built into the camsprocket inside the engine.

Many things can and do go wrong with this design. Wear can develop between the spark advancer shaft and the camshaft that it rides in, causing sideplay in the points cam. The return springs can weaken or break, causing lazy spark advance return. The camsprocket is riveted together and eventually the rivets loosen up, allowing the camchain sprocket to loosen and walk back and forth within the mechanism. There is also some slop between the end of the points cam shaft and the plate that it engages in, within the camsprocket assembly causing some initial spark advance on start up. Honda Dream camsprockets have heavier weights and lighter return springs to speed up the spark timing on those models.  Camsprockets used on CB/CL models have lighter, smaller weights and stiffer return springs compared to those of the Dream models.

Rule #6

There are some “universal” engine parts that are shared within all three engine types. The kickstarter shafts, shift drums (except rotary gearbox types), primary chain tensioners, shift forks and shift selector shafts are usually the same in all models. 1960-62 shift shafts were shorter than later versions, however. Dreams have a completely different set of transmission ratios than the shared CB/CL gearboxes. There are 4 different clutch assembly setups, depending upon the application. The camchains, camchain guide rollers and camchain tensioners are all interchangeable, however the camchain tensioners have two different bolt patterns, changing in 1966.

Rule #7

There are “round bowl” and “square bowl” carburetor types, but they will interchange on various models. The round bowl versions came first, replaced by square bowl designs around 1964 for most models.  You can interchange the CB and CL77 carburetors if you swap out the jetting components.

Carbs come in 22mm and 26mm sizes for 250 and 305cc models, respectively. The 22mm carburetors for the 250s (and 305 Dreams) are all different in function and mounting points. Only the CB72 Super Hawks have the “power jet” carburetor functions. The CL72 Scrambler carburetors look identical, externally, however the power jet functions were deleted.  

Dream carburetors for 250-305s are interchangeable with minor jetting adjustments. Good carb parts source, as well as other 250-305 repair parts is www.4into1.com  or https://classichondarestoration.com The most common problem with carburetors is that the mounting flanges become warped, causing air leaks. Second most common problem is that the slide bores become distorted, causing the slides to stick when the engines heat up. With careful work, both conditions can be overcome.

Rule #8

Crankshafts all differ between the three models, as well as having a different balance factor between the 250 and 305s. The biggest challenge in rebuilding these engines is that the wrist pin holes in the un-bushed small rod ends get out of round, causing a part-throttle “chatter” sound. Honda made .004” oversized pins, however machining the pin bores to match is quite difficult with the crankshaft in its full assembly mode.  Competent machine shops can press the crankshafts apart, bore the rods to the oversize and/or re-bush the rods back to stock size again. Obviously, this will become an expensive repair step, if needed. The majority of the engines I have taken apart have had loose pin fits after 10k miles. If the engines have ever had a running piston seizure, the chances of rod damage are quite high.

Rule #9

The electric starter versions of these engines (CA/CB72-77) have a total of 5 chains in place to operate the motorcycle. The original primary chains, which connect the crankshaft to the clutch outer, stretch easily and begin to strike the inside surfaces of the clutch cover when they are out of spec. OEM primary chains are pretty much extinct, however a chain/sprocket company in the UK has come up with an endless 3/8x3/8 chain which works perfectly in these engines. They can also supply the tiny oil filter drive chain, camchains and starter chains. In a pinch, camchains can be cut up and shortened for use in the electric starter models.  www.sprocketsunlimited.com

Rule #10

Rebuilding the petcocks on the CB and CL models is fairly straight forward and plenty of repair kits are available.  Reserve tubes can crack or become broken off after 50 years of use. Overflow tubes can be replaced with 5mm brass tubing from a hobby shop. Dream petcocks are a whole different animal. They share a lot of internal parts with the 125-150 Benly models, however the outlet fittings are on opposite sized from each other, so the bodies are not interchangeable. Most aftermarket repair kits are not properly made, so cause installation and sealing problems.  Most of the internal sealing parts are still available from Honda warehouses and are highly recommended. A few parts are NLA in the US, but can be sourced from eBay sellers in Thailand and other Asian countries. Look out for warped petcock bodies that no longer seal properly against the bottom of the fuel tanks.

Obviously, there are many areas of these bikes that require careful study so that any parts purchases are not wasted due to a lack of knowledge about the kinds of changes that have occurred over the years. I offer comprehensive digital download packages of restoration reference files that are targeted for each of the 3 models.  See my site: www.vintagehonda.com for details and to order. I always welcome questions and can often guide people in the right direction for parts purchases and other restoration resources around the world.

                                                                       Bill Silver aka MrHonda

Eighth-liter wonders… the Honda 125... singles, twins, fours and fives!

Street bike models

As Honda’s new Benly J-series machines evolved, from 1953-58, the engine displacement began at 89cc and eventually rose to a full 125cc, with the introduction of the 1955 JB Benly model, which took advantage of a new law allowing for this larger-sized engine in Japan. There were severe restrictions on manufacturers in the 1950s, which eventually loosened up, as the decade passed.

The Benly J-series 125cc engines doubled in horsepower from 4.5 to 9.5 between the 1955 and 1958 editions, as these simple pushrod-powered bikes fought to compete and overcome challenges from the hundreds of other Japanese motorcycle manufacturers in post-war Japan. When the limit was reached for the single-cylinder models, the “new” 125cc Benly models became OHC, short-stroke, twins with 44x41 engine dimensions. Similar to the new 250-305cc Dream twins, the first-year 1958 models, named C90, came without electric starter motor options.  By 1959, Honda expanded the line-up, adding the new electric-start model C92, along with a highly-engineered “Sport” version called the CB92 Benly Super Sport. And with a twist of the boring bar, new 154cc models, based upon the 125cc engine design were announced as C95 and even a CB95 for that one year.

All Benly twins rode on leading-link suspension up front and a simple pressed-steel swing arm in the back, located by a pair of non-adjustable telescopic shock absorbers.  The standard Benly 125-150 models looked like little 7/8ths scale versions of the larger 250-305 Dreams, which came to market in late 1957, thus they have become known as “Baby Dreams” by some owners.

These sturdy little OHC twins featured a single carburetor which split the mixture into each cylinder alternately, due to the 360 degree crankshaft configuration. Ignition was a simple single set of contact points operated from the end of the crankshaft for accurate ignition timing. A single 6v dual-tower ignition coil was bolted up inside the backbone frame with its twin spark plug wire leads dangling downwards connecting to small 10mm spark plugs for the first few years. Eventually, the spark plug size was increased to 12mm and numerous changes to crankshafts and other engine internals yielded a fast and reliable small-bore street machine. The C92 models were rated at 11.5hp at 9,500rpms, while the CB92 Super Sports model carried a 15hp rating at 10,500 rpms; power unheard of in those days. Honda made specific tank badges for most of their models, until 1968. The little Benly models used “Benly” only badges for 1959-61, then switched to “Benly 125” badges for the remaining years of production, including the use on the CR93 street bikes.

American Honda did import a 1959 CA92 125cc model for just that one year, followed by the larger-bore 154cc CA95s (named the Honda 150Touring), which sold from 1960-65. The US did not impose cc restrictions on small bikes and riders, unlike Japan, so it was “the bigger the better” for the US market enthusiasts. Honda responded rapidly to the unfolding new bike market, offering the 305cc options for the larger models, over the almost identical 250cc versions.

Other than the CB92 Super Sport models, of which only about 1,000 came to the US, there were no other 125cc offerings in America until 1967, when the SS125A/CL125A models were introduced. Design-wise, the “new” 125cc twins were visual duplicates for the early Benly models, which shared the “side camchain” feature, but it became apparent that almost none of the early Benly parts were being shared with the new-generation machines.

There was a Honda CB125 (CB93) model, which was a 125cc version of the CB160 (CB96), but they were not officially imported into the US.  The mysterious Honda CBXX codes were finally dropped in 1968 for the most part, when the bikes were designated by their displacement size; i.e. CB350, CL175, CB450, etc.

In the US, only the pressed-steel framed models (with 17” wheels) were offered in that 1967-68 timeframe, whereas the domestic and European editions had twin-carb, 5-speed versions stuffed into tubular frames with full 18” wheel sets. Non-US models were marked as CB125K3 for the early models, which featured CB77-style 2:1 instrument gauges with tach and speedo in one single oval-shaped unit. These bikes featured an 11,500 rpm redline and all the full features of the larger CB/CL175 models, which were seen in the US.

Honda did use the single carburetor engine in the domestic CD125 models, again not seen in the US, but they were delivered in Canada at the same time as the SS/CL125A models were sold in America. In photos of European models, the same side-cam engine was used in various frame/chassis setups, with variations in the locations of the ignition systems and other details.

When Honda finally retired their aging 4-speed S90/CT90/SL90 horizontal singles in 1969, their replacement was first released in Japan as the CB90, a nearly-vertical OHC style single with a 5 speed transmission. By 1970, the engine was bored out to 100cc and released to the US markets in CB100 and CL100 versions. These continued until 1973 when Honda broke out the boring bar, once again, bring the displacement out to 122cc as the new CB125S0 edition. It was basically a bored out CB100 and continued to have the same drum-brake as the base 100cc models. When Honda rolled out the 1974 version of the CB125 (CB125S1), enthusiasts were surprised to see a full-featured model with a tachometer and a clever, mechanically-operated disc brake in the front wheel. Curb weight climbed only 10 lbs from the near-200lb weight of the S90/CL90 models of the 1960s, but the bikes top speeds barely improved at all. While many S90s seemed to be able to touch 70mph, the CB125S1 was a 65 mph machine, even with a tail-wind. Just about all of the 100-125cc editions had a single 22mm carburetor attached, with only minor jetting setting them apart.

(Side-bar story: Your author bought and tuned a 1974 CB125S1 for the 125cc production class racing in Southern California. At the end of the season he captured the 125cc class championship in both the CMC and AFM racing organizations. With help from Yoshimura-supplied engine parts, the bike regularly reached speeds of 80+mph and had the best brakes of the class.) 

The CB125S1 and 1975 CB125S2 models were identical apart from their paint schemes, still sharing the same one-piece cylinder head design inherited from the CB90/100 models. The minimalist cam bearing support of that cylinder head design lead to worn cam/head bearings, causing the camshafts to wobble around in the head during operation. With the point cam mounted at the end of the camshaft, ignition timing also suffered inaccuracies, especially at high rpms. Hard-core racers, who campaigned the SL125 variants in off-road racing, resorted to machining the camshaft and cylinder heads for needle bearing conversions to help secure the camshaft firmly in the cylinder head.

By 1976, the revised CB126 ’76 models gained 2ccs, a new 2-piece cylinder head, but lost their tachometers. The cylinder head was also redesigned with a split-port intake runner to help boost mid-range torque and engine efficiency and the carburetors were finally rubber-mounted to help reduce fuel frothing at high rpms. Continued use of small-bore carburetors and mild valve timing yielded reliable performance, but nothing truly noteworthy.

The 1977-78 editions were again just a color change upgrade. By 1979 the front disc brake disappeared, replaced by the generic drum brake package seen in the first editions. The 1979-80 models continued much the same as the earlier editions but with new mufflers and a styling package. Finally a CDI ignition package was installed for the 1981-84 models. The 1984 models were upgraded to 12v, after 14 years of suffering with tiny 6v electric power.

Honda did not offer any CB125S models in 1983, owing to a backlog of unsold models in their inventories. The 1984-85 editions were all made in Brazil, as Honda phased out the 125cc streetbike line-up for good.

Not sold in the US, but were offered to MSF course sites was the CB125T. This engine was a derivation of the US-spec CM185T and CM200T designs (forerunners of the Honda 250 Rebel). While the US “Cruiser” models had 360 degree crankshafts,  6v electrics, single carburetors and 4-speed gearboxes, the CB125Ts came out of the box with 180 degree crankshafts, 12 v electrics, dual carbs and a 5-speed transmission. The first-generation bikes came with regular, spoke wire wheels and the mechanical disc brake seen on the CB125S models.  The dry-weight figures were in the 250 lb range, but these bikes would pull upwards of 80mph at their 12k rpm redlines. While the early bikes never made it to the US, American Honda worked out some kind of a lend-lease program with the Motorcycle Safety Foundation organization and supplied some specially-equipped CB125TT models as “learner” bikes for the rider programs. The bikes were never supposed to be titled or registered in the US, due to lack of EPA approvals on that model.

The CB125T2 models had Comstar wheels, a front hydraulic brake and other amenities in keeping with the design themes of the 1980s and early 1990s. The bikes were widely distributed throughout Europe, Asia, Africa and Australia, where countries created rider/taxation restrictions on certain classes of riders.

Workhorse model CG125 Honda singles were mass-produced and featured a plain, pushrod engine configuration vs. the typical OHC models sold as a higher level model. Low-powered but reliable as a rock, these bikes suffered at the hands of non-mechanics worldwide, where they were treated more as a transportation appliance than as a spirited means of riding joys. Just another example of Honda targeting a specific market with their very “Benly” product line. Convenience over all other considerations, with reliability as a must. Millions would agree that the target was met successfully.

Roadracer 125s

Primarily offered as a high-performance street machine, Honda did offer CB92R models, kitted for 125cc class road racing in the US. Starting with the base CB92 machine, a long list of “YB” race kit options was available as a turn-key racer or the individual parts could be ordered separately. YB parts included: pistons/rings, camshaft, valve springs, racing ignition coil, two lengths of racing megaphones, alloy rims, tachometer option, racing seat, footpegs, starter delete and stator/rotor delete options and even pre-drilled fasteners. CB92Rs were capable of nearly 85 mph at 11.500rpms.

In 1962-3 Honda offered the CR93 production roadracer and a handful of "street bike" versions. Few of these made it to the US, but they were popular racing machines in Japan and the UK. These bikes were DOHC, 4 valve powered with gear-driven camshaft drives, capable of approaching 100 mph.

Honda made huge headways with their 125s, eventually on the world GP stage, however their first efforts in 1959 were a bit under the competition’s levels of achievement. The RC141 was a 44x41mm twin with 2 valves per cylinder, featuring a bevel-drive system to drive the camshafts.  It was quickly replaced by the 4 valve per cylinder RC142 at the IOM races. Honda actually used CB92 bikes as trainers for the fresh-from-Japan riders who had never seen the IOM course before.  It was said that the bike actually arrived with knobby tires fitted, as used on the Mr. Asama race course, which is made of volcanic cinders. Honda quickly fitted proper roadracing tires on their bikes for the rest of the events, but the first bikes all had leading-link suspensions at the front end, which lead to rather poor lap times. Honda did achieve a team prize for their 6-7-8 finishes in their first attempt at the IOM course, however.

Honda returned in 1960-61 with RC163 and 2RC-163 models, still DOHC 4 valve twins with 6-speed transmissions. By 1963 Honda served up a 125cc four cylinder model RC146, followed by 1964 2RC-146 and 4RC-146 models with 7-speed transmissions. In 1965-66 Honda dropped the big 5-cylinder, 8-speed bomb upon the 125cc class and won championships easily. These engines revved to 22,000 rpms and were capable of over 125 mph.

Honda left the world motorcycle racing stage in 1967, as they concentrated upon F-1 racing and the manufacture of automobiles and other automotive equipment. The next “factory” racer models to become available to a select few in the US were the CR125 Elsinore-based MT125R racers. The first generations had the same mechanical front disc brake and used a fairly stock CR125M engine with a special close-ratio gearbox. Feather-light, they could eclipse 110-mph if you could keep them on the boil. Later MT125R2 models were equipped with a water-cooled top end and hydraulic disc brake on the front wheel. These bikes were raced extensively in the late 1970s and into the 1980s. Eventually, as Honda re-entered the world of roadracing with their new NSR250 and NSR500, the 125cc class became the place to learn your roadracing craft, so Honda tooled up roadrace -specific RS125/NSR125 machines for world-wide distribution.

Dual-Sport/Off-road models

Honda offered a different set of “YB” racing parts for the CB92s, which created a “Scrambler” version of the 1960-62 streetbike. Dave Ekins, famous off-road racer in the 1950-60s, successfully raced a CB95 version of the bike in off-road competition; however it was eventually disqualified because it wasn’t a model that was officially sold in the US. That was Honda’s only 125cc-sized racer in the 1960s.

Honda broke new ground with 2-stroke CR125M Elsinore MX racers and the MT125 Elsinore street version, starting in 1974. This was Honda’s first departure from the reliable, but heavy and underpowered, four- stroke singles, which could never make the same kind of horsepower that a two-stroke single of the same size can generate.

Honda offered Dual-Sport and Trials 125cc versions of these early singles in TL125, CL125, SL125 and XL125 models.  Ironically, the SL125s were offered as early as 1971, while the street models didn’t arrive until two years later. The early XL125 models were pepped-up with higher compression pistons, upgraded camshaft, larger valves and a 24mm carburetor. The 1979-1985 XL125S models featured a slick 6-speed transmission. The TL125s, offered for just 3 years, spanned the transition of one-piece to two-piece cylinder heads, as did the other versions. TL125s were specifically designed to go SLOW, so they were detuned and setup for slow speed riding and low-end torque for Trials events.

By 1985, the four-stroke 125cc Honda singles had died out, in all of their variations. There was a NX125 offered from 1989-92, but these little dual-sport machines sold poorly, at least in the US.

You can’t buy them here, in the US, but the 21^st Century has brought bikes like the CBR125R, water-cooled, SOHC, 2-valve, four stroke single in a cool sport bike chassis, with fuel injection! So, I guess after 58 years the concept of the “Honda 125” will never die after all.

These are just the highlights of the 125cc Honda series. I know there are many, many other 125cc models, sold in specific countries/markets which I have never seen or heard of before. In countries where 50cc bikes rule, a 125cc model is a “big bike” to those enthusiasts. Long live the Honda 125!

Bill “MrHonda” Silver

The Honda Dream battery nightmare…

Benly vs. Dream battery confusion

Although you will find parts ads and other listings for Honda “Dreams,” which wind up describing CA95 Benly or CA160 Touring 160 models (sometimes called Baby Dreams), the only true 1960s Honda “Dreams” are the 250-305cc models.  Only a few parts will actually interchange between the two series (Dream vs. Benly), such as the ignition switches and the rear shock covers. I usually refer to Benly/CA160 models as a “7/8 scale Dream.” Despite similarities on the chassis design, headlight shape, suspension function and 16” wheel sizes, Honda made the 150-160 models completely different all over.

Another parts issue that arises for new owner’s is their bikes often need new batteries, so they search for “Honda Dream” battery, instead of the correct “Honda Benly” (or CA95 CA160) battery. The Benly series machines are ALL SIX volt electrical systems, so a “Dream” battery won’t fit in the battery tray, in any way, shape or form and if it did, it would immediately fry all the electrical components in a Benly series bike.  A secondary cause for confusion was that the CA160 models (no longer called Benlys, although they were essentially a 150cc Benly with a 160 engine installed) continued to use the SIX volt electrics, even though the CB160 and CL160s had adopted TWELVE volt systems. This is just one part of the battery dilemma for vintage Honda Benly-Dream owners.

Early vs. Late Dream Battery issues

In a perfect world, Honda 250-305 Dreams would all have the same TWELVE volt battery, but of course they do not.  When the first dry-sump 250-305cc Dreams were released in 1957-60 timeframe, they had large SIX volt batteries installed, in order to crank over the engine efficiently. When the new wet-sump Dreams were released in late 1960, the revised machine was equipped with a full TWELVE volt electrical system. Honda cranked out thousands of early 250-305cc Dreams from 1960-65/66 with the same battery, which was somewhat taller and thinner than many other batteries on the market.

In the meantime, Honda was using the 12N9-3A battery in all of their CB72-77 Hawk/Super Hawk machines with great effect. Apparently Honda decided to use the same battery in both CA and CB models, so they re-engineered the frame, battery box, tool tray, battery ground strap, battery cover and knob to accommodate the change. This changeover occurred at CA-72 1000330 (early 1965 production) and at CA77-1010863 (late 1965 or early 1966). The 12N9-3A battery is 5.3” x 3” x 5.5” (LWH).

Invariably, new Dream owners go online, see Honda Dream Battery listings and assume that one battery fits all models, including theirs. So, you can imagine the surprised buyer when the battery that they receive is nothing close to what they needed, if their bike is the “early” style battery type.  The few remaining early type batteries are sold as WISCO JB-2 editions. There was a GS branded battery offered under a slightly different number, but Honda has long discontinued the early style YUASA MB J4-12 OEM batteries due to their rather sparse sales numbers and singular applications.  The early batteries are 7 3/8" x 2 9/16" x 5 1/2" (LWH) YUASA batteries are a highly known and respected manufacturer of motorcycle batteries, but I have often found that there are ordering errors, even on their own website. The last time I checked their site, the 12N9-3A batteries were no longer listed. 

The first generation of those “new style” batteries had horizontal terminal posts, but in recent years, the posts were changed to an upright design, but no change was made to the part number. There are inexpensive aftermarket batteries being made now in Taiwan and elsewhere in SE Asia, with tiny 5mm attachment bolts instead of the previously supplied 6mm hardware. So, double check the specifications of the hardware to avoid disappointments.  Current EBay listings for Honda Dream batteries show various types, some showing 1963-66 applications, which makes no sense whatsoever. There are new maintenance free batteries and even lithium ion batteries coming to market now, but nothing new that actually fits the early Dream model frames and hardware properly.

So, why is that important?

Good Question!

The answer is that the battery holds an air filter body cover in place, on the side of the frame. The cover has no attachments or hardware to secure it where it belongs.  Only the correct-sized battery will hold the cover in the frame recess and be properly secured in place by the tool tray.  You cannot mix-match batteries, tool trays, battery ground straps, battery covers/latch knobs and their respective frames.

Check the illustrations accompanying this report to see some of the details surrounding this long-standing issue for Honda Dream owners.

"Early Dream" 12v battery

Correct 12N9-3A battery for "Late Dreams" and CB72-77 Hawks

Bill “MrHonda” Silver

The mystery of the 1963 “5K” CA77 Dreams

I was recently contacted by a SoCal gentleman who was complaining about some oil leaks on his 1963 CA77 Dream. The serial numbers on this bike are CA78-311781 with engine number CA77E-316817. Whereas, virtually all 250-305cc Honda twins have serial numbers which are within 200 digits from each other, this one has numbers with a five thousand+ number spread.  If you deduct the five thousand number difference, the engine/frame serial numbers are only 36 numbers apart. 

Below are some examples of strike-through numbers, apparently done at the factory, but could have been done at a dealership. The mystery will never be solved, I'm afraid.

I recall hearing from a few CA77 owners who were wondering if their bikes had the original engines in them because their serial numbers were a little over five thousand numbers apart. I just figured that the bikes had experienced an engine swap somewhere along the line and that was that.

However, over the past few months, a VJMC member and Dream enthusiast, named Bill Soli, began inquiring about the fact that more than a few bikes from the 1963 model ranges were showing up with a five thousand difference in their numbers.  He had been polling forum members from various sources and collecting numerous examples of this five thousand number spread effect. Obviously, this was not just a random case of engine swapping now. Something significant was going on, which was not reported within the Honda serial number listings, released to date.

American Honda’s parts books listings left a big gap in the timeframe from when the original 1960-62 bikes were changed over to the restyled “CA78” versions, These were only mentioned as beginning production in 1964. Apparently, 1963 models didn’t seem to exist, according to the AHMC records. Honda’s parts books show 901 versions of the CA77 models being built in the 1962 year of production, then just skip to the six digit serial numbers of 1964.

Here’s an abbreviated look at Honda’s serial number sequences for 1963, transposed from their parts books of 1968:

’63 Type                Engine                                                    Frame

C72        C72E-310001-323269                       C72-310001-323269

CII72     C72E-310001-349404                       C72-340001-352302

CA72     CA72E-310001-311910                    CA72-310001-311910

C77        C77E-310001-310896                       C77-310001-310896

CA77     CA77E-310001-314731                    CA77-310001-314731

There is nothing remarkable shown here, which is what I have used as a reference for a number of years.

The next entries are for 1964:

‘64 Type (1)

CIII72   C72E-100001-110852                       C72-100001-110852

CIIIA72 CA72E-100001-100760                   CA72-100001-100760

C78        C77E-100001-101512                       C78-100001-101512

CA78     CA77E-100001-108176                    CA78-100001-108176

‘64 Type (2)

CIII72   C72E-400001-405219                       C72-400001-405030

CIIIA72 CA72-400001-401542                      CA72-400001-401520

C78        C77E-400001-400978                       C78-400001-400975

CA78     CA77E-400001-403456                    CA78-400001-403456

You can see that Honda went a little schizoid with their numbering system. First, they used a series of 6 digit serial numbers that began with a ONE for a while, they then changed their minds and began using serial numbers beginning with a FOUR, which is more inline with the previous years.

Secondly, they switched from calling out their chassis numbers from C/CA77 to C/CA78. This corresponds to the changeover from the early seamless fuel tanks to the reshaped seamed tanks, which also relocated the fuel crossover hoses from the front of the fuel tank to the middle section. The chromed fuel tank side covers were reshaped, along with the rubber knee pads. This also ushered in the changed fuel tank’s plastic emblems script from “Honda Dream 250 or Dream 300” to just plain “Honda 250” or “Honda 300” styles.

There are other changes in the C/CA78 series, regarding the handlebars and controls. The clamp-on mirrors, sourced from the CE71, were replaced with CB72 lever brackets, which incorporated mirror mounts on a raised pad. The hidden throttle cable system, sometimes called “Slide throttle” was also introduced. On the “delete” list was the formerly included tire pump, with mounting brackets and lock.

What really occurred, shown in some entries within the large “World version” of the parts books, is that the changeover from C/CA77 to C/CA78 happened during the 1963 model year, instead. Adding to the confusion is that the 252-305cc Dream was ALWAYS called a C/CA72-77 Dream and the 305 engines were ALWAYS stamped with C/CA77 all the way through their entire production life. If you see an engine with the numbers stamped C/CA78E, it is a fake.

Apparently, the only way that Honda could differentiate the engines destined for C/CA78s was to add five thousand numbers to the serial numbers. Why five thousand numbers? Who knows and we may never find out, anyway.

Suffice to say, now, that owner’s of 1963-series Honda Dream motorcycles who find themselves faced with this five thousand number spread between engine and frame numbers can now relax and be assured that their bikes came from the factory, serialized in this way.

Please note that I have been using C/CA77 or C/CA78 notations to cover both U.S (CA72-77) and domestic/Euro versions, which were identified as C77 or C78 models. U.S. models came with turn signals deleted, plus dual seats included; whereas many domestic C-77/78 models might have had sheet-metal handlebars, winkers (turn signals), solo seats w/luggage racks and even rotary shift gearboxes.

The whole CA77/CA78 engine/frame number system causes great confusion among new owners and all I can tell them is that “it is what it is.” Honda had their own way of doing things, logical or not, but not to fret when the frame numbers don’t seem to “match” the engine numbers.  All you have to remember is that ALL 305cc Dreams had CA77 engines, no matter what the frame numbers indicate.

Hopefully, I have cleared up some confusion about the serial number system for the 1963 editions.  Next time, we can discuss why Honda put a SEVEN in the serial numbers, right after the first digit, instead of a zero.  Isn’t this fun?      Bill “MrHonda” Silver

Early or Late? How do you tell the difference between vintage Hondas?

The terms “early” and “late” are somewhat subjective and somewhat objective, depending on how you are applying the definition as it applies to vintage Honda motorcycles. Since American Honda setup shop in 1958, just about everything sold before 1960-61 would be considered “really early,” by most aficionados of the marque. Other than the first generation Honda Cubs, the CB92 and CA95 Benlys, the “big bikes” (250-305cc) were dry-sump Dreams and few of those were sold in the beginning.

Once Honda’s production machinery really ramped up in the early 1960s, bikes came pouring off the lines in as little as every 15 seconds! That figure applies to Honda step-thru Cub models, however. Those early pushrod bikes were run continuously until about 1965, when the OHC engine designs took over. Some versions of the Honda Cub 50s (and some 90cc models) have been in continuous production since 1959, with over 65 million units produced, world-wide.

Other “early” small-bore machines were the OHV Honda 90 street and trail bikes, known as the C200 and the CT200. Again, these were superseded by OHC engines in the 1965 era.

Looking at the small twins, the 150cc Benly Touring 150s, which were also released in 1959, had a styling makeover in 1963, where the fuel tank, panels, rubbers, handlebars and mufflers were all redesigned.

Similarly, the “early” 250-305cc Dreams had their own rework sessions in late 1963, where the model changed from C(CA)77 to C(CA)78, which brought changes to the fuel tank, side panels, rubbers, tank badges and handlebar hardware. So, the true CA77 models can be considered “early” while the CA78s  are recognized as “late” versions.  While these styling changes are readily apparent, that was not the end of the design process. Honda reconfigured the frame, tool tray, battery ground, battery and side covers (and knobs) in 1966, changing the battery size/shape from the early, tall, thin battery to the wider, shorter 12N9-3A unit, also used in the CB77s.

Most collectors think the 1961-64 CB77s, equipped with flat handlebars, steel forks, flat seats and reverse-needle speedometer/tachometers were considered to be the classic “early versions.” In 1965, the flat handlebars gave way to low-rise units and the speedo-tach meter set mirrored the concentric CB450 Black Bomber instruments. 1966 brought alloy forks, requiring a new front fender stay design, plus the upswept seat shape, all of which carried through to the end of production.  Those features are commonly referred to as “late CB77” editions.

For many Scrambler owners, the 1962-65 CL72 250cc Scramblers had the look and the sounds associated with “early” models, which included slender alloy fenders, straight exhaust pipes with no muffler can on the back and the mostly ineffective “small brake” wheels/hubs.  In 1965, the CL77 was released, initially as a big bore motor transplant for the CL72. The fenders were changed to steel and they gradually widened to better encompass the rear wheel debris throw-off and to help keep them from cracking. The 1965 CL72 and CL77s had a “slip-on” muffler, which wrapped around the ends of the twin exhaust pipes, to better reduce the high-pitched, high-decibel exhaust notes. Those were quickly removed by the owners, forcing Honda to weld mufflers onto the later generation of exhaust systems.

By 1966, the CL77s were completely re-engineered with new alloy forks, double-leading shoe brakes, rubber mounted rear fender, seat, exhaust, footpegs, fork ears and a thicker chain guard. The net effect was a more beefy profile, carrying more weight and losing the slim, sleek look of the original concept. However, these “later” bikes were far more reliable and had the much-needed braking power lacking in the “early” models.

In 1965, Honda’s engineers refined the 250-305 engines, lowering the compression, changing the fin shape pattern of the cylinder heads, adding “square bowl” carburetors and other details that held them apart from the “early” editions.

1966 brought wholesale changes to the suspension systems on many models. The “early” S90, CB160, CB77 and CL77 caught up to the CB450K0 Black Bombers by having all of their fork lowers changed from the frame-color steel style to silver-painted alloy forks. The fork style helps delineate the “early” and “late” division line on all of those models.

In some cases, either the year or the country specification made a distinction between “early” and “late” type of handlebars. In some cases, early model Honda Sport Cubs, Super 90s and CB160s had “low bar” handlebar configurations. As production and sales increased in the US, a determination was made that the US bikes should have “Western” handlebars (read higher and wider) than the domestic and European counterparts.  So, the cool little “W” shaped handlebars for the C110 Sport Cubs and Super 90s gave way to unattractive and out of proportion “Western” handlebar configurations, requiring whole new cable sets for each model. Many of the bikes with “A” (for America) designators, like CA110, CA77 and US-specification CB160s and CB77s all had “Western bar” handlebar/cable combinations. 

However, if the bikes came into the US before 1964, they often had the lower handlebar sets, found on non-US models. If you are restoring a 1960s model bike, exactly to as-sold specifications, then you will have to study your parts books carefully to establish which handlebars and cables are needed to make the bike correct for that year edition.

Up to 1968, turn signals were not specified for the US market. The Honda S90 and CL90s and the CB/CL450s were a few of the carry-over machines, which came to the US without turn signals in the beginning and then had them added towards the end of production, which carried on past the 1968 cut-off date. Obviously, the turn signal/no turn signal machines are the dividing line between “early” and “late” models in Honda’s lineup for those affected by the change.

Another aspect of “late/early” models are how the bikes were affected by the change from JIS thread pitch to ISO pitches, starting with the 1968 production models.  The 250-305s and 160s were out of production by the end of 1967, so are not necessarily affected. You will find some models, like the “early” CL175K0 Scramblers, which are built with two sets of fasteners, as production progressed into the 1968-beyond models.

Learning to speak Italian… again!

I really have to stop throwing out internet bids on “interesting” bikes and forgetting that I did it until I receive notice that I have “won the auction”.

Those of you who have followed my ramblings over the past 10 years (or more) might recall that I acquired a somewhat troublesome Benelli Sei (750 six cylinder) machine from a local seller who had had it since the 1970s. That bike was fun to ride and sounded amazing… when it would start. Even a $500 ignition system never insured that the engine would fire up easily. That, along with the factory defective transmission gearset (there was a recall that the bike never received) led me to let it go to a local Italian bike dealer who had the bike restored.

So, here we are again, with almost the same bike, but with fewer cylinders this time. The Benelli Quattro 500 is the Honda CB500 engine clone in virtually the same chassis as the Sei. The big departure is that instead of a double disc Brembo front brake, it has a double-sided drum brake system with 4 brake shoes up front.

The bike caught my eye on some Internet link to a big auction in Wisconsin in mid Oct. It was open to internet bids a few weeks ahead of the actual date, so I thought I would test the waters to see how much interest there was in this rare machine. Benelli updated the models with the double disc brake wheel later on, but few of these bikes were probably ever sold in the US in either form. I do recall seeing one for sale locally a number of years ago and visiting the seller’s place to see it in the flesh/metal. It, too, was a drum-brake model, but it wasn’t running and I shied away from it due to lack of parts and general knowledge of the series.

By the time I paid for this bike, plus a hefty 18% buyers fee and rounded up a U-ship guy to haul it out for $450, the initial bid cost had increased by 50% again. All that was shown in the auction page was both sides of the green bike and a short sentence about the frame number and perhaps the mileage on the odometer.  The auction company did provide a WI title a few weeks after the bike arrived, which is helpful for getting a CA title for the bike, but you still have to jump through the DMV/CHP hoops to finalize the paperwork.

The main source for replacement parts is a company in Germany, who seemed to have gathered up all the remaining Benelli parts for all the models they could find. They have microfiche illustrations on-line and generally ship parts out quickly and at reasonable prices, all things considered. I did inquire about the H-shaped molded fuel hose connector in advance of receiving the bike and they did not have a replacement part for that item. There are four carburetors and two petcocks to connect all the plumbing together so I will have to round up T-fittings to get it all fueling properly.

                                                                    Auction photo

Arrival…

The bike arrived within 10 days from the auction, riding tail-gunner on the back of a long, double-axle open trailer. At 20 feet, it doesn’t look TOO bad, but as you got closer the condition issues became more and more apparent. Fortunately, it did have some air in the tires and the 4 shoe front brake did function to a point. The friendly driver helped me push it up the driveway and into the awaiting bike lift for future repairs and a deeper inspection of all systems.  It was one of those heart-stopping moments where you say to yourself, “What did I get myself into now?”

The first look revealed that there were NO spark plugs in the engine, no ignition switch key provided and the engine was LOCKED UP solid. The first thing to do was to squirt WD40 penetrating oil down each spark plug hole and hope that it would work some magic on the stuck pistons.

The design of the battery box is such that you cannot remove the back side of the air filter box to service the filter. Removal of various attached electrical components finally allowed the battery box removal. At that point, the bolt holding the filter cover turned out to be part of the inside of the housing, not accessible unless you remove the carburetors and airbox. The carburetors are connected with intake manifold rubbers which attach to intake manifolds which are bolted onto the back side of the cylinder head. The air filter box connects to the carburetors with short connectors, which unlike the outside angled versions on a CB500 Honda, are all straight-back designed parts. Pulling the connectors off the air box and back off the carburetors allowed for carburetor removal. One of the carburetor tops was missing and the throttle cable had already been disconnected. SOMEONE had been in there before, probably trying to get it running sometime in the past 10-20 years.

On the plus side, the odometer only showed 1506 miles and the original Pirelli branded tires were showing little wear, which seemed to verify the miles shown on the speedometer. There was rust everywhere on chromed parts, other than the fenders, which were unaffected for some reason. There was surface rust inside the fuel tank, of course, but the carburetors were clean inside the bowls. The plastic meter box, which mounts to the upper fork bridge with a couple of bolts was broken at both attachment points.  It was déjà vu all over again, as the basic architecture of the Quattro 500 is nearly identical to the 6 cylinder Sei. The Sei had double disc brakes up front, but both bikes shared the same rear hub and suspension. The Sei has alloy rims, where the cheaper 500 was left with chrome steel hoops, which were both rusted badly on this machine.

The fork ears had been chromed, along with the front brake hub stays from the factory. The brake stays were suffering from peeling chrome and the fork ears were in similar condition. The chromed headlight bucket was somewhat better, but the headlight rim chrome was badly pitted.  The 4into 4 mufflers were solid, but with surface rust and pitting down in the creases. The header pipes were still in remarkably good condition, however.

Once the carburetors were removed, work commenced on getting the top end of the engine removed for damage assessment. Unlike Honda, Benelli engineers used #1 Phillips head screws to retain the top rocker arm cover. Fortunately, they mostly loosened with a few blows of the impact driver with a matching driver tip. More challenges were revealed when two of the Allen screws that hold the top cover end caps wouldn’t come out, stripping the hex heads of the 5mm screws. After trying various methods of removal, the heads were drilled off so the caps could be taken off. The end caps cover the last two end screws that hold the top cover to the cylinder head. The screws thread into the ends of the rocker arm shafts and there was no apparent reason for two to come off and two to be firmly entrenched in their positions. It took about a half hour of careful drilling the screws out of the ends of the shafts, then rethreading the holes successfully. The cover then came off easily revealing shiny metal parts inside. The rocker arm pads were all like new and the camshaft lobes appeared to be barely broken in.

The camshaft is secured to the camsprocket with two bolts, but somehow the engine had stopped with both bolts lying right at horizontal positions. It’s tight quarters in there, so although the camshaft bolts could be accessed (remember the engine was frozen), you can’t back them all the way out of the camshaft sprocket as the heads hit the inside of the cylinder head opening. I tried to loosen the camsprocket bolts with an open ended wrench, but they didn’t budge at all. I figured that the bolts had been installed with Lock-tite thread locker, so the only option was to try to loosen them with a large sharp chisel. The chisel was able to catch a corner of the bolts at just the right angle, but it took considerable amount of hammering to get them to begin to rotate loose from the camshaft bolt holes.

Eventually, both bolts were loosened successfully, but couldn’t be removed due to their proximity to the edges of the cylinder head. A Dremel tool with a cut-off wheel was used to cut half of the bolt head away just enough to allow the bolt to be removed from the forward bolt hole. The rear one remained in place, however. Using a long-handled adjustable wrench, I applied some torque on the crankshaft bolt, hoping that the engine would give just a little bit. Suddenly, the crankshaft turned about 10 degrees and the camshaft bolt was then clear of the cylinder head for removal.  With the camchain free of the camshaft, the engine was turned back and forth a few times, finally allowing for full rotation of the crankshaft and full movement of the pistons.

The camchain tensioner bolts to the back of the head and cylinder with 2 bolts, but unlike Honda’s design, the mechanism can’t be locked in place for removal. When the bolts were removed, the tensioner spring wanted to push up against the back of the camchain, preventing removal of the camchain from the sprocket teeth. The tensioner was pulled upwards, but hit the frame backbone tube before it was clear of the cylinder head. Finally, it appeared that the tensioner could be compressed with my fingers and the whole unit rotated 90 degrees, which then allowed the top to be tipped over and just clear of the frame tube.

Once the camchain was off the camsprocket, the camshaft was removed and a wire attached to the camchain to prevent it from dropping too far into the engine.  The cylinder head is attached with a series of flanged nuts and washers, some of which are sealed off by little rubber plugs in the head.  With all the nuts removed, the head pulled up with a little nudging here and there. The valves had quite a bit of soft carbon on them, but showed little signs of use. The now-exposed piston crowns showed some signs of varnish, carbon and moisture corrosion. The cylinder bores had some pitting around the edges of where the pistons were sitting for so many years. The corrosion had eaten into the bores just enough to catch a fingernail on the edges, so the choice was to pull the cylinders for a re-bore.

A set of .50 aftermarket Honda CB500 pistons/rings were ordered up from Japan for $125 and the cylinders will go off to my favorite machine shop for $160 of machine work. Lots of scraping was involved to get the leftover gasket material off the engine cases, all the while trying to keep the loose bits from entering the open bores in the crankcase. The pistons all came off of the pins with little fuss, so  there is no concern about damaged pin bores in the rods.

Progressing slowly…

The a/m pistons came in from Japan in about a week. My machinist bored the cylinders and noted that one piston was a bit smaller than the other three, so bored the holes accordingly. After some wire-brushing to clean off excess corrosion, the cylinders got a bit of color added back. Benelli actually painted the cylinder blocks gold and the heads black from the factory! After an hour of careful prepping and assembly, the cylinders glided onto the pistons and the assembly awaited the completion of the cylinder head.

The cylinder head was disassembled and de-carboned. All the valve faces and seats looked great, but valve stem seals were hardened, so were replaced with gasket kit parts. In the process of reassembly one of the valve stem keepers dematerialized and could not be recovered despite an extensive search of the immediate area. I discovered that the valves were 5.5mm stems like the Honda valve stem sizes, but Honda keepers didn’t fit, so replacements have to come from Germany.

I was ordering parts from Benelli-Bauer anyway, as they are one of the last couple of resources for NOS Benelli parts. They can supply replacement instrument cases and most everything else that I have asked for so far.

In the meantime, I decided to go the poor-man’s route and have the rims powdercoated satin black, along with the formerly-chromed fork ears. Some new tires were ordered and after all the spokes were cleaned up, the finished rims were re-spoked back to the de-rusted hubs. There was extensive amounts of rust inside the drums, however it did clean off with extensive use of wire wheels and abrasives. The brake shoes were glazed and had a thin film of corrosion embedded into the faces. A little light sanding brought back the original surfaces however.

Rather than purchase all the Benelli gasket parts, one-by-one, I just ordered up a whole CB500 Four gasket kit and installed all of those parts without issue. Apart from the slightly-angled forward cylinders, much of the top end components are exact dimensions of Honda’s OEM CB500 designs.

The parts order from Germany took almost 2 weeks to arrive, so to speed up the assembly process an OEM Honda exhaust valve was ordered to match the keepers that were already purchased, but didn’t fit the groove pattern on the Benelli valve stem.  Problem solved and the cylinder head was bolted down, torqued to specs.  Two new camsprocket bolts were ordered to replace the butchered ones and the rest of the original parts reinstalled.

My experience with the Benelli Sei mirrored the current one of the Quattro. The intake manifold rubbers were broken/cracked causing obvious air leaks. On the Sei, I ordered up OEM Honda manifolds and installed a set on the Sei, which did not have the original air box in place. The manifolds were a little longer than the originals, but it didn’t matter because of the pod filter installation. The Quattro carb/manifold/airbox combo is a REALLY tight fit; even worse than a standard CB500-550 setup.

Sadly, after the long wait for the box of parts from Germany, it became obvious that the intake manifolds shipped were of two types/lengths. Three might have been actual Sei units and one an actual Quattro replacement part.  A message back to Germany, accompanied with photos, confirmed the mistake and a promise to ship the correct parts came back quickly.

Eyeballing the manifold situation, it seemed that the “wrong ones” could be used in the interim but because they were of a thicker material the original manifold clamps wouldn’t reach around to fit the increased diameter. Also, the process of wedging the carburetor rack in between the bolt-on manifold stubs on the head it became apparent that there was left no room for the carburetor rack to fit between the two components. I would imagine that the “correct” way to remove/replace the carburetors is to loosen the engine mounts and tilt it forward, which is required on a CBX Honda Six. 

To override that necessity, I removed the manifold stub bolts and replaced them with bolts, so I could slide the whole assembly in laterally and fit the carb inlets to the new air cleaner box connectors. I could only use 2 of the original rubber manifold clamps on the one correct manifold that was supplied, so the other three were clamped with 2” hose clamps that I had on hand. The two rubber manifold types have different ribbed patterns, but they were close enough to allow a tight fit once paired with new clamps.

Another couple of hours were spent doing R&R on the meter box installation, which was a snug fit for all the components. All the wiring connections to the instrument warning lights needed to be disconnected so the harness could be pulled through the small slit on the bottom of the meter box housing. The wiring diagrams found online were all in German or Italian and of very faint and small drawings. That had to be reworked on the computer and printed out to help with the wiring installation. The recommended replacement Yuasa battery had side posts instead of top posts, so some angled adapters were fabricated. Fortunately, apart from some blown out bulbs and some that had melted the plastic upper meter housing plate, the electrics mostly came to life without blowing any fuses. The fuse block is typically mid-20^th Century design with little bullet ended ceramic fuses and flimsy fuse holder tabs.  Corrosion had built up on the ends, so everything needed cleaning to promote good electrical connectivity.

The ignition points were corroded, so required more cleaning and adjustment. I hesitantly tried the starter button and the engine began to spin over, somewhat slowly, but the result was encouraging. 

The fuel tank was cleaned and sealed with 2 part Caswell epoxy coatings. New generic Italian style petcocks were located and installed to complete the fuel tank repairs. Some ¼” T fittings were purchased at the auto parts store and little pieces of 5.5 OEM Honda fuel line were cut up and fitted to tie the fuel system components together.

Running and nearly ready to sell.

Initially the engine spun over, but wouldn’t fire up, even with the choke fully applied. There is a lot of friction with new pistons/rings and a lack of ring sealing in the beginning which caused some difficulties in getting the engine spun over fast enough to get everything synched up, but with a jumper system in place, the long-dormant engine finally fired up on all cylinders, sounding quite like a copy of a Honda CB500 Four with 4 into 4 exhaust pipes. The carbs were fussy, at first. The idle speed was erratic, either too low or too high, probably owing to a sticking spark advancer unit.

The engine does start and run, but not idle well. The charging system light stayed ON, so the left generator cover was removed for inspection. The Bosch charging system uses a set of brushes to contact the slip rings on the end of the rotor shaft, not unlike an automotive alternator. While the components all appeared to be in good condition and electrical wiring checked okay, the whole outer brush/stator assembly was basically just floating on the end of the rotor shaft because the four 5mm mounting bolts were MISSING! Long 5x45mm bolts are not easily found locally, so a quick look online gave some clues about where to find them. I called local hardware/bolt stores and discovered that there were some in stock… 45 of them in a box! I only needed 3, but the whole box was only $6 and change, so I bought the box and have more than 40 to share with anyone out there who might need such a fastener.

The bike continued to be hard starting, didn’t want to idle and one carburetor began to overflow due to a failed plastic float assembly. Carb kits were ordered and the wait continues for replacement intake manifold rubber connectors. All the spares will go with the bike, which has been put up for sale now.

As what has happened several times in the past, I am facing surgery again, this time for a worn out ankle. The recovery requires 3 months of non-weight bearing on the right foot, so getting this project wrapped up and ready for sale has become a race against time.

A quick trip to the CHP office for verification and then back to DMV to push through the completed paperwork was successful, so the bike can be officially titled in the state of California. Having a titled bike helps the sales process immensely so I always do the legwork to get the paperwork in order for the next owner.

 I have to promise myself NOT to repeat this process again, especially with another rare Italian Honda copy model, such as the Quattro 500. In an eerie coincidence, during the Quattro project, I was contacted by a man who I met at the January 2018 Mods and Rockers ride event. He had bought a storage unit full of bikes, including a silver 1976 Benelli Sei! He wasn’t going to sell it right away (although there is always a price that works in the end), but needed someone’s help to get his running properly. I offered to help, but warned him of my upcoming surgery and lack of ability to do motorcycle work for at least three months afterwards. Unfortunately, the sands of time have about run out on that offer…

Bill Silver            aka “MrItalianHonda” for the end of 2018.

It’s raining CB92s this month…..

My primary focus on vintage Hondas has been the variations of the 250-305cc models for more than a decade.  Having owned, repaired and overhauled numerous vintage big twins, I am perfectly at home with those models.

Honda’s CB92 Super Sport machines are extremely rare in the US, having only received about 1,000 machines in the 1960-62 era and many of those were supposedly the racing versions. I owned CB92 #24 about 30 years ago, which was a bike originally sold here in San Diego. In the years since about half a dozen more have come my way and were resold without taking on full restorations. Obviously, after 58 years, the parts sources are very thin. Additionally, the changes made during production, complicates the picture even further.

Honda began production in 1959 with both a 125cc CB92 and a companion 150cc version CB95. Bear in mind that these were newly designed OHC twins which revved to 10k rpms, but only carried a little over one quart of oil in the crankcases. Early bikes suffered crankshaft failures and left side piston seizures when run hard, especially of the oil level dropped below the safe mark.

From 1959 through 1962, there were three different crankshafts and a matching number of crankcase changes to follow. The first generation crankshafts had a 1mm larger center main bearing than the end bearings, all located in the cases with split half ring retainers. At high rpms the bearings could actually rotate in the cases and not enough oil was passing through the crankshaft to feed the left side crankpin.  Honda did an unusual stopgap modification by machining an oil passage in the base of the cylinder block that lead from the oil feed stud hole across the back and into a window that was machined in the rear of the left side cylinder bore.  A special gasket was created to match the oil channel work.  The early cases featured a “rear breather” design that collected and separated the oil solids from the crankcase vapors at high speeds and allowed just the separated air to escape.

The second generation featured main bearings of all the same diameter, but the center main was locked in place with a locating pin to ensure that it was getting a constant oil feed from above. The end bearings continued to be of the split ring design.  The crankcases were changed to make the breather system function back inside the top cylinder head cover with a vent/drain line coming off of a fitting.

Finally, in 1962, they pinned all three bearings, so the cases were changed again to reflect those modifications. Obviously, the crankshafts and crankcases all have different part numbers and design features which preclude mixing and matching parts from other years.

A good friend in AZ had purchased a couple of less than perfect CB92s and dropped off an engine for me to rebuild. It had suffered a severe piston seizure early in its life and was parked for decades. The engine required a full cleaning and vapor blasting to recover the original finish, plus all the fasteners needed to be re-zinc plated. Fresh pistons and rings were installed back into the original STD bores which were not damaged. All the rocker arms were replaced, but the camshaft appeared to be in serviceable condition. All new valves were installed due to cupping of the seats and valve faces. After a few weeks of running parts back and forth to machine shops, the engine was reassembled and stood waiting for pickup.

As time went on, the VJMC West Coast Rally was announced in Prescott, AZ, so I saved John a 600 mile round trip by dropping off the rebuilt engine at his house. During the interim he pulled another CB92 engine apart for rebuild and had already cleaned and re-plated all the parts. The engine cases had suffered a bizarre damage situation to one of the carburetor cover mounting posts. Apparently one of the mounting screws was seized into the mount and probable use of an impact driver had broken the whole mount off of the case, taking a large chunk of the top case with it.

John sent the case off to Colorado where a skilled welder had managed to re-weld the chunk back into the case, blending the repairs so well that it was almost invisible on the outside.  Good save as that is the half that contains the serial numbers.

When the parts were unpacked, I noticed that the 1960 engine cases had a non-matching 1961 crankshaft installed! Apparently the engine was run like this with the center main bearing free to spin around inside the cases as there was no contact with the crankcase bores.  So, the hunt was on for a new crankshaft with the larger center main bearing. After almost 60 years, finding NOS CB92 parts has become problematical, but within a week, I managed to flush out three different correct crankshafts for sale. Two were out of the country (Thailand and the UK), but the last one came from a stash in WA state, where a long time owner/racer of CB92s had some leftovers buried in his garage.

Had the whole units not been discovered, the Plan B was to buy one of the center main bearings and have a machine shop rebuild the crankshaft with a new main bearing in the middle. These crankshafts are small and difficult to press apart and back together again, so I am glad to have a whole new correct unit to use as a replacement part.

In the meantime, my friend John Stein, in LA, wanted me to revive a 1960 CB92 which he had owned for the past 30 years. I agreed to take on the revival (not restoration) work, so that made three 1960 CB92 bikes or engines that have come to the shop in the past month. That bike showed up dirty and sad looking with a mismatched paint color on the headlight bucket, incorrect tail light, wrong brake cable and other woes, but some restoration work had been done to the hubs and wheels. The bike must have been raced at sometime as there were some crash damage scuffs remaining, a racing rear tire on the back and an all aluminum cylinder block installed.  Plus there were no mufflers on the bike, just a set of loud factory megaphones from the race kit. The bike featured a YB racing seat, as well, plus a tachometer in place of the speedometer.

While all of this was happening, I received a message from a CB92 owner in Los Angeles area who was moving to AZ soon and wanted to sell his “project” 1960 CB92. At the moment, my bike inventory is pretty much at max levels, including a 2013 CB1100, 1988 CBR250R (250 four cylinder), 1988 Hawk NT650 with 1,000 original miles and a newly acquired 1990 NC30 VFR400R. With one 1960 CB92 on the bike stand and another 1960 engine on the work bench, things are in overflow status.

The LA bike was disassembled, had been repainted metallic green, had a chopped off front fender and the kneepad was disintegrating. The engine had 150 cylinders, but the head was still stock 125 parts. The bike had been stored in poor conditions, so there is lots of rust and patina on the parts visible in photos.  The price was at the upper level for what was there, but it had been the seller’s bike since 1964 and he was aware of the value of the bike, even as a parts source. 

Reality check…

After much consideration and parts availability checking, I decided not to pursue the LA CB92 project bike. The 1960 bikes seem to be prone to needing new crankshafts and based upon recent searches, their availability and cost are budget busters. Some of the rare chassis parts are available from a source in Japan, but the seller doesn’t ship to the US, so they would need to be relayed from one of my Japanese based contacts out here to California, increasing costs dramatically.

The current 1960 CB92 engine was held up for a new crankshaft, which arrived recently, but without end bearings or the special thrust washers. I ordered the thrust washers from DSS in the UK, who has to nab them from their partner resource in Holland, so delivery time can be a couple of weeks in the end.  I asked about the spare C92 engine crankshaft still in AZ and they were intact. So, with a little persuasion, the end of the crankshaft was cleaned off and washers shipped out with the set of CA95 cylinders which need to be re-bored before assembly.

Once the cylinders were bored, much of the reassembly went smoothly. The oil filter needed was the shorter version and not serviced. The small 4mm screws tend to get stuck and often the heads are damaged when removal is attempted. I did manage to get them loose and the unit cleaned. Some allen head screws were supplied as replacements, but the thread pitch is slightly different between JIS and ISO so the holes were rethreaded. Eventually, all the bits fell into place and the engine was picked up in late Oct.

Top end tear down…

The 1960 #517 CB92 on the bike lift finally got to the point where I could try the electric starter to spin the engine over in preparation for a startup after 30 years. The starter solenoid just buzzed a little bit, probably due to dirty internal contacts. After a stint on the battery charger, finally the engine spun over with the electric starter, but not very briskly even with the spark plugs removed. A compression check revealed 80 psi on the right cylinder and about 85 psi on the right side, which is way under the suggested 130 psi in the manuals.

The motor was eased down onto the work table and the top end removed. Within the alloy YB racing cylinder block were two STD bore YB pistons, both of which were carboned up on top, but showed little wear on the piston skirts or within the bores. The top ring was removed and checked in the bore for end gap width, but appeared to be on the minimum end of specs.

The head was checked for compression losses and both exhaust valves had odd pits on the valve seat faces, so will be replaced. The camshaft was stamped YB in 2 places. All the cam lobes and rocker arms appeared to be fully serviceable as-is.  Intake valves were de-carboned and re-installed as their seats were still nice and shiny thin rings. Exhaust seats were lightly cleaned and should be a good match for new valves. The ends of the valve stems appeared to be nearly unmarked, so the engine run time must have been minimal on new parts.

The low compression was probably due to the exhaust valves leaking, but the extended valve timing of the camshaft can actually reduce the measured compression readings because of the YB cam timing. The combustion chambers and piston crowns were pretty coked up with burned oil deposits, but the exact cause of excess oil consumption is somewhat mysterious given the condition of the parts inspected so far.

Once some fresh valves are installed, we’ll see what the readings come up to afterwards. The old gaskets were very difficult to remove and more than an hour and a half of labor was expended in just getting the parts cleaned and free of leftover gasket residues. This is always the least pleasant portion of engine rebuilds on vintage Hondas, as far as I am concerned.

Progress…

Amazingly new correct 205-coded stainless exhaust valves are still available from eBay sellers. The seats were cleaned up and new valves lapped in. New head gasket, sealing rings and a few oil seals were installed and the engine eventually reinstalled. The engine has to go back in with the head first, which is awkward to do with a single jack. I eventually used 2 small floor jacks to get it stuffed back into place. I can do an engine swap on a CB77 in half the time as these little Benly engines.

I managed to track down a new starter solenoid to replace the one whose mounting ears had broken off and were replaced with strap metal. This was another rare part that was found with an eBay seller who had several in stock and took a “best offer” of about 30% less than “retail” for it. CB92 parts like that are probably slow movers in the US, as there were so few bikes sold here and fewer remaining to repair or restore.

Start up and wrap up…

Initially, the bike engine didn’t want to fire up, but after about 15 good kicks, it sputtered to life and kept running with little or no choke, even when cold. The bike stutters just off-idle, then cleans up and pulls through the gears. An open-megaphone CB92 is not something that you want to spend a lot of time on, particularly in a residential neighborhood. I made a couple of mid-day passes up and down the streets, right around home. It pulled past redline going down a long hill, but struggled on the way back up. The 4 speed gearbox has somewhat wide ratios, so it falls off the powerband when you upshift from 2^nd to 3^rd gears, under load.

I suspect that it needs a larger main jet for pulling high speeds, but also needs a slide with a bigger cutaway or a needle with a fatter taper to help lean out the low end. Despite the hi-dome YB pistons, the D8HA spark plugs screw all the way down and haven’t had their electrodes hammered shut yet.  I think the longer duration YB camshaft profile hurts the bottom end power, causing metering problems for the carburetor, as well as lowering the compression readings at idle.

The clutch was initially “stuck” but leaving it in 3^rd gear at 30 mph with the clutch lever pulled in, finally released the pack and the clutch began to work normally. A “best practice” would be to disassemble the clutch pack and clean up the steel plates, but this is to be an occasional bike for running around the block up in LA, so probably isn’t a significant factor in the grand scheme of things.

The task was to get it up and running reliably and make sure that nothing falls off of it during short jaunts. The steering is “twitchy” when changing directions, as if the steering stem is a little bent. There were some signs of at least one lay-down incident, but nothing significant was seen as far as chassis damage. The tires are over 30 years old and the rear one is an old Yokohama road race tire. The front is probably the original OEM 1960 rib tire, so there is a lack of flexibility in the tire combo. The bikes ride like buckboards anyway, with little suspension compliance on either end. A few quick rides did nothing to endear these little Benly buzzers to me and more than in the past. They are an iconic design, but with technology from the 1950s, it leaves a lot to be desired.