Wednesday, February 17, 2021

Honda 250-305s… pros and cons

 As the alleged “Guru” of the 1960s 250-305cc twins, I have learned a lot about these bikes, most of which has been written into my “Restoration Reference Guides” for each of the three models. In monitoring various forums and vintage Honda groups, I continue to see people digging these bikes out of garages and falling down buildings, just in time to start a rescue project. Usually, the new owners have little in the way of knowledge or reference beyond Honda’s little efforts to create shop manuals. Scrambler owners are surprised to find out that there was no “305” updated version of the “250” shop manual! The CL72 shop manual is a decent place to start but there are no references to the “big-brakes” and alloy forks, so you have to just figure it out by yourself or ask for knowledgeable assistance.

I have owned all of the US-market 250-305s, including a couple of CE71 dry-sump models. I used my first-hand experience with the various bikes owned in the past to compile the reference guides and share what I know with forums and other groups. These bikes have stood the test of time with classic styling, reliability (when properly maintained) and amazing performance and longevity. There were shortcomings in a few areas, which are well-known to most veteran owners, but the appreciation of these well-made motorcycles continues to grow. So, here’s my take on the three pillars of vintage Honda twins.

Engines:

With engines that were lowest in horsepower, Dream engines can last for many years, however, there are features that are shared with all of the 250-305s, which cause problems with higher miles accumulated on these unique machines. Honda’s choice to bury the spark advancer system deep inside the cylinder head in the middle of the camshaft sprocket is a puzzler. Ironically, the CE71 Dream Sports did have a separate spark advancer on the outer end of the camshaft, but when Honda changed from dry-sump to wet-sump engines, they put the spark advancer in the middle of the camshaft.

Problems arise here when the engines have aged and have been ridden higher mileages. The return springs on the advancer weights tend to stretch and loosen, which prevents the weights from coming back to a normal stopped position. The weights also have little bonded stoppers on the ends to cushion the return to rest. These rubbers harden and eventually break off, causing the weights to return further than originally designed. This adds more travel to the advancer weights, which causes an excessive spark advance to come into play. In order to prevent the spark advance from going beyond 45 degrees, you have to retard the idle spark timing back towards TDC, which engines don’t really like. Idle spark timing is best in the 5-10 degrees before top dead center, so setting idle timing at TDC can create rough idle, plus the weights tend to swing out prematurely causing the idle speed to raise unnecessarily.

Spark timing has a big effect on manifold vacuum signals which are acting on the carburetor’s idle circuits. Advanced spark timing increases vacuum signals, which pull more fuel into the engine, which then makes it run faster, so the whole effect snowballs out of control. On a single-carb Dream, the vacuum signals are amplified as two cylinders are pulling vacuum signals alternately.

What else had become apparent over the years, is that the point cams, which open the points at just the right time are not symmetrical on both lobes, often varying 5 degrees between engine cycles. You can watch the spark signals waver back and forth using a dynamic timing light. Another factor that shows up with varying timing signals is that the camsprockets are basically riveted together and after years of enduring camshaft lobes pushing and pulling the camshaft over center each engine cycle, the rivets loosen up, allowing the center camchain sprocket to begin to shift back and forth on each engine rotation. This affects both valve timing and ignition timing, as the parts shudder against each other during engine operation.

The camsprockets can be TIG-welded at the corners to anchor the sprocket to the rest of the assembly, but when the weight pivots wear out and/or the rubber cushions fail, you really can’t remedy the situation, short of replacing it with a new or good used replacement. Adding to the complexity of the situation, Honda changed the camshafts and sprocket spline dimensions through the years, so you must match a replacement sprocket to your camshaft splines. And finally, the camsprockets for Dreams and CB/Cls are different in that the Dreams have a faster spark advance curve using larger, heavier weights that swing out quicker as engine speeds increase. Are you following me so far?

Another note about the engines; they have some wear parts in the bottom end, too. The bronze low gear bushing has a raised center rib to keep two gears apart, but the thrust from the low gear will eventually wear the rib out so it slides off as a separate ring. The kickstarter pawl is in constant contact with the inside of the low gear and eventually wears out causing slippage when kickstarting the engine. The other wear item are the primary chains, which originally were offered in three different strengths, but superseded to the 268 code ones for the Super Hawks. All these endless chains are the same size and length and with over 250,000 engines built, the supplies have dwindled down to next to nothing.

CA72-77 Dreams

Considering Dreams were basically designed in the late 1950s, the basic chassis didn’t change a lot for 10 years. Many of the wet-sump Dream parts share their roots with the 1957-60 dry-sump models. On the plus-side, they were designed to be “Touring” bikes, ones that keep the rider as clean as possible during the ride. Large fenders and enclosed chain guards help prevent unnecessary road grime and chain lube from reaching the rider and passenger. Domestic versions had solo seats and luggage racks which could either be used for hauling materials or with the installation of a clip-on passenger seat, you have a dual rider machine.

All Dreams have the Type 2 (360 firing) crankshaft, which helps give the little single-carb engine a boost in torque, coupled with a lower geared transmission to help move things along The 360 crankshaft firing engine can cause some frequency vibrations that typically cause fractures back in the rear fender/tail light region, due to the sheet-metal construction of the frame. Dreams have shorter cam timing for low-end torque, but run out of breath past 8k rpms due to the single carburetor and cam timing limitations. Dream engines have lower compression ratios than the CB/CL counterparts.

Apart from a lack of horsepower (rated around 24 ponies), the riding experience is hampered by (1. a lack of suspension damping/control at both ends and (2. terrible, tiny, single-leading shoe brakes on both wheels. Other rider complaints center around the “late Dream” (CA78) slide throttle for the carburetor, which has no real return to idle function if you let go of the throttle. Early Dreams used a twist throttle, like the CB/Cls, which allows more control of the throttle function.

Mechanically, for the most part, the Dream engines are pretty much the same. The early model machines used a tall, thin and long 12v battery that was only used on that series of machines and is long out of production. From 1966-onward, Honda retooled the bike to take the 12N9-3A battery used in Super Hawks and lawn tractors. These are much more commonly available, except there are some versions that have vertical posts, vs the flat horizontal posts that the bikes were designed for originally.

CB72-77 Super Hawks

These hotrod “cafe racer” models, which offered flat handlebars a decade before “cafe racer” was a thing, are the star performers of the trio. Early models, with the 9.5 compression engines could hit right around 100 mph with nice big 200mm (8 inch) dual leading shoe brakes to bring them to a rapid halt. Early 1961 models had SLS front brakes (still 8”) and DLS rears for some reason. Honda saw the light early on and switched back to DLS fronts, which were probably some of the most powerful production brakes during that era. The drawback on DLS brakes is that they are very powerful GOING FORWARD. They lose all of their mechanical advantage when the bike is going backwards, however. It’s a somewhat disconcerting feeling to try to hold a Super Hawk on an inclined stop sign/light, when it wants to slowly creep backwards on you, no matter how hard you pull the brake lever in. Most of the time that isn’t a problem, but be aware of the shortcomings of the brake system designs if you come up against this situation; nose pointed uphill at a stop.

With flat bars, the riding posture is leaning forward into the wind, balanced by the air pressure pushing back against your chest. The “flat bar” CB72-77s have “the look” that is a classic pose and mostly preferred over the later 1966-67 low rise bars offered in the US. In actual practice, the low rise handlebars offer more rider comfort for around town riding and for those of us in our advancing years.

My pet peeve for CBs are the stupid friction pivoting driver footpegs and the non-folding passenger pegs. Invariably, as you are shifting the bike around while getting it pointed down the driveway is that the drive pegs brush up against your shins and promptly fold UP and stay UP until you manually push them downwards again. It’s very annoying to be riding around and having to be concerned with the footpeg positions, which are easily displaced from normal.

The rear pegs are solid bars with rubber peg rubbers and if you are standing next to the bike and pushing it around, you will invariably contact the rear pegs with your shins. In the past, I have opted to find the domestic non-folding driver pegs used outside of the US and on CP77s and leaving the rear pegs off, as there is seldom a reason to have a passenger on the back of these bikes

More irritants center around the goofy forward-kicking kickstarter arm. It is either contacting your instep when you are riding and particularly when you are trying to use the rear brake pedal and/or the extended end of the kickstarter arm catches your pants leg and starts to pull you off balance as you struggle to untangle your pants from the kickstarter arm before you tip over in the street. I hate that!

Because of the nature of the spine frame arrangement, dropping the engine out for service is relatively simple, apart from the fact that the engine weighs about 115 lbs. The frame design allows for light weight and responsive handling. The overall vibration levels are much less than the enclosed frame of the CL72-77 Scramblers, under similar circumstances. The Type 1 engine configuration (180 degree crankshaft) gives off a high-frequency, low amplitude vibration that is kinder to the chassis parts, although chain guards and tail lights have been known to have vibration cracks from the engines rocking couple firing. You can watch the rear fenders wiggle back and forth when the engines are idling and the bike is on the center stand.

Super Hawks had distinctively different front fork designs with the early versions made up of steel tubing and ends welded onto the tubes to create the axle holders and the threaded-on fork seal holders. The steel fork tubes can be easily damaged by inadvertent installation of excessively long fender and brake arm bolts that screw into the welded and threaded mounting pads. When the bolts bottom out in the tubing, it distorts the bore shape and the fork bushings jam up inside. The Type 2 forks were cast aluminum parts, with 2 bolt clamps at the bottom to hold the axle and offset bosses to mount the fender bracket. You can tell the difference on a stock bike right away, as the Type 1 steel forks are painted the same color as the frame, while the Type 2 alloy fork sliders are silver on all models.

CL72-77 Scramblers

From 1962-67, something like 80,000 Scramblers made their way to market, mostly in the US. When Dave Ekins and Bill Robertson took brand new CL72s down to the tip of Baja in early 1962, the stunt did wonders for Honda’s sales of their new “dual sport” Honda Scrambler model. Sales skyrocketed in the following years, then really exploded when Honda dropped a 305cc engine in the same chassis. CL77 production ran into about 68,000 units. With the sales successes of the 250 Scrambler, suddenly Honda thought, “Why don’t we make Scrambler versions of all our models?” and so they did. Honda did a bolt-on kit for the CB450 Bombers to make them into “450 Scramblers” back in 1966, before designing a companion model to the CB450 street bikes. There were Scrambler versions of 90s, 160s, 175s, 350 and aforementioned 450s. When the new OHC horizontal 50-70cc engines were produced Honda made CL70 Scramblers. Everyone LOVED the Honda Scramblers for their style and their perceived abilities to go off-road (just a little bit). Certainly, a lot of street bikes were stripped down and raced or ridden off-road, back then, but the stock suspensions were woefully inadequate for serious competition. And it was the same for the 250-305 Scramblers, which had the look, ground clearance and makings of an occasional off-road machine, but really needed some aftermarket help. Japanese shock technology was sorely lacking in the 1960s, with shocks limited to a couple of inches of travel and very little damping capability. That opened up new industries that specialized in improved shocks and fork kits to increase travel and dampening abilities.

The key feature that makes the Scramblers so much different than the Super Hawks is the level of vibration transmitted into the chassis from the engine and exhaust system mounting. Scrambler engines didn’t have electric starters for weight reasons, but that allowed for the frames to have a single down-tube in front of the engine to help strengthen the frame in off-road situations. The closed tube frame design lead to increased vibration transmission throughout the whole chassis, coupled with the long resonant exhaust pipes, which were bolted directly to the frame, caused increases in vibration levels throughout the whole bike.

Scrambler engines are basically Super Hawk engines without the tach drive and electric starter, so all the preceding comments about the engines apply equally here.

Scramblers were always geared shorter for better off-road riding and that lead to more rpms on the highway for long trips. The increased vibration began to cause failures of chain guards and fenders. Because the engine is bolted directly to the frame, all Honda engineers could do was to begin to isolate the rider from the vibration sources. Rubber-mounting of components lead to new footpegs, seat mounts, exhaust system mounts, rear fender mounts, battery mounting systems and even front fork ear cushions to reduce the headlight bulb failure rates. The CL77 rear wheel sprockets lost a few more teeth (37 vs 40 on the 250), as well, because many riders loved the look of the Scramblers, but didn’t always care to go off-road and highway riding got tiring after extended exposures to the vibration levels coming from the engines and being transmitted throughout the whole machine.

With high demand for parts and dwindling supplies, it can easily cost upwards of $10k to do a full restoration of these iconic machines. Most owners opt for the straight pipes with or without baffles or the “Snuff-or-Not” movable exhaust washer accessories. The long pipes have a distinctive resonance that gives them their unique sound.

Bill “MrHonda” Silver



Thursday, January 14, 2021

Highway robbery at the CA DMV…

 Having owned/sold something like 400 cars and motorcycles in the past 55 years, I guess I have been lucky not to get entangled with the DMV “non-op” regulations that can incur big penalties for not paying regular yearly registration fees. A couple of years ago, I let my Jaguar XJ8 get away from me as DMV didn’t send the renewal forms and I didn’t pay attention to the month tag on the car. That was a $100 hit that didn’t sit well with me. But usually, when dealing with 50-year-old derelict Honda bikes, they are generally “out of the system” so that no penalties are incurred because of the lack of registration activity caused DMV to purge the vehicle from their database.

I think a general feeling has been that if the vehicle hasn’t been registered in the last 10 years, that it must be out of the DMV system. Unfortunately, I got a big financial shock last week when I went to register a couple of rather sad, but mostly complete CB77 Super Hawks.

The bikes came from a vintage Honda wrangler up in the LA area, who had amassed about 30 bikes in his garage and back yard, having picked them up in the LA region over the years. The seller had posted the bikes on Facebook forums for what seemed like a good deal, given the 20-foot photos included in the announcement. He actually had posted to the Honda Dream forum instead of the 250-305 or CB72-77 forum, so there was a little less of a response than normal. His location was about a 2-hour drive, each way, from me in Spring Valley, Ca. Having been caught, like everyone else, in the midst of the pandemic catastrophe without a lot to do, I figured a couple of CB77s would keep me busy for awhile getting them back on their feet/wheels and into some semblance of full function and safety again.


The bikes were generally complete; a 1964 still had stock type mufflers, although the left one had a large and long dent underneath and the right side was pretty rusted on the surface and proved to be one of the low-cost Dixie replicas from days gone by. They did both run after a fashion and I was able to drive them up and down the street for a minute or two, just to check out their mechanical function. The bikes were weathered with rusty spokes and rims, cracked cables, faded and chipped black paint and general corrosion on formerly chromed or polished surfaces.


The 1964 bike had a CA plate with 2010 tags affixed. The 1965 bike had an old CA black plate hanging off the license plate ears, but the numbers indicated that it was probably from a much earlier machine. After a bit of wrangling, I bought the pair of bikes, plus a CL77 spare engine that was seized and had an electric starter hanging off of the front and a Dream top cylinder head cover affixed. See previous stories about the mechanical woes encountered after they were brought back home.


Once the bikes had been gotten back to some level of function and safety (after about $600 spent on the basics), I offered them up for sale with “BOS” bill of sale only as I assumed that the guy I got them from had cleared the titles or at least felt confident that they were no longer in the DMV system. Lacking titles is always a crapshoot for anyone who wants to take over a restoration project, so I finally hauled them down to DMV for verification of the serial numbers to start the paperwork trail.

The woman who I have dealt with over the past few years did the initial inspection of the numbers, but then asked me how I knew what the model year was. I told her that I had a lot of experience with these bikes and that often I wound up having to take them to the CHP office for their verification process and that the officer there knew me and knew that I had first-hand knowledge of these bikes and could verify that actual year dates based upon the serial numbers. I have hauled a number of odd or dead bikes to him in the past and with my knowledge of the bikes and showing how I came to those conclusions, he’s always passed the bikes as-is without concerns.

The line at DMV was LONG so I just got the correct forms from the DMV inspector and called CHP to make an appointment for them to check the bikes out. Initially, the first available appointment was 2 weeks out, but I was told to check in early on Tues/Thursday mornings to see if there were cancellations. I called the following Tuesday morning and after overcoming getting no live person on the phone, tried a random phone extension number and got someone to pick up the phone. They checked with the in-house inspector and asked if I could come in at 10AM today! I told them that I would be there promptly and gathered up the bikes to load up in my Tacoma for the 14 mile trip to the El Cajon CHP office. To my surprise, the usual officer that I normally work with was on vacation, so I had to explain what I was trying to accomplish with the bikes and offered a printout of Honda’s CB72-77 serial number chart taken from the factory parts manuals for consideration. After a half-hour, the officer came back and had cleared the paperwork concerns, signing off both bikes as okay to go.

Feeling lucky in the moment, I turned the truck back to the Chula Vista DMV office to see if I could push through the paperwork and get titles for both bikes. Apparently, I caught them on a good day, as the wait time was minimal to get to the customer service counter. A woman there sifted through my various bits of paper, forms, and bills of sale and then checked the VIN numbers in the computer. Much to my surprise and shock, she said that both bikes were still in the system registered to someone other than the guy I got the bikes from in the first place. One had records going back to 1997 for the last registration transaction. That was for the 1965 bike and apparently had been put on non-operation status decades ago, so the “title-only” fee was $61. The 1964 bike, which I had been grooming as a possible “keeper” was a whole different story…


I asked about how long the vehicles stayed in DMV computer records and was told that they can stay in for 20 years! If anyone contacts DMV with VIN number requests for any car or bike, the system captures the request and starts the clock over again if the serial numbers are still valid and stored in the database. Shockingly, the 10-year-old tags on the 1964 bike were never put on non-op status, so there were fees and penalties that came up to a total of $805! When I tried to invoke the DMV rules to override the back fees and penalties according to a website posting that went:

(Always fill out a statement of fact (REG256) with this statement: "I am a collector and this is a collector vehicle exempt from back fees as defined in VC 4604 paragraph B")

5051 collector is defined:

(a) "Collector" is the owner of one or more vehicles described in

Section 5004 or of one or more special interest vehicles, as defined

in this article, who collects, purchases, acquires, trades, or

disposes of the vehicle, or parts thereof, for his or her own use, in

order to preserve, restore, and maintain the vehicle for hobby or

historical purposes.

VC4604 Is the code that describes the non-op penalties, Section D lists the exceptions:

(d) A certification is not required to be filed pursuant to

subdivision (a) for one or more of the following:

Paragraph 3 is the collectable car exception that you NEED to keep in mind and ask for a supervisor if any problem:

(3) A vehicle described in Section 5004, 5004.5, or 5051, as

provided in Section 4604.2. However, the registered owner may file a

certificate of non-operation in lieu of the certification specified in

subdivision (a).

VC5004(a) defines collectible vehicles. Paragraph 3 is the broadest category:

5004. (a) Notwithstanding any other provision of this code, any owner of a vehicle described in paragraph (1), (2), or (3) which is operated or moved over the highway primarily for the purpose of historical exhibition or other similar purpose shall, upon application in the manner and at the time prescribed by the department, be issued special identification plates for the vehicle:

(3) A vehicle which was manufactured after 1922, is at least 25 years old, and is of historic interest.

5004. (a) Notwithstanding any other provision of this code, any owner of a vehicle described in paragraph (1), (2), or (3) which is operated or moved over the highway primarily for the purpose of historical exhibition or other similar purpose shall, upon application in the manner and at the time prescribed by the department, be issued special identification plates for the vehicle:

(1) A motor vehicle with an engine of 16 or more cylinders manufactured prior to 1965.

(2) A motor vehicle manufactured in the year 1922 or prior thereto.

(3) A vehicle which was manufactured after 1922, is at least 25 years old, and is of historic interest.

I was told that while that clause might be valid, my choices were either to pay that amount or pay 10 years of old registration fees at $118 per year. While the clerk was shuffling the paperwork and waiting for my reply, I called the seller of the bikes to explain my plight. The call went to voicemail, but I left a message about my shock and dismay at being faced with a huge registration bill.

With hopes of the chance that I might get some of the money back from the seller, I gulped and offered my debit card to the DMV clerk and she happily hit the account for $805. I offered a few nicely put comments about the unfairness of the penalties, which she agreed with but could do nothing more about the situation. On the drive home, my phone rang and the seller offered to refund half of the amount which was still way more than it should have cost me under normal circumstances, but still was something of an offset.

In hindsight, I should have run the plate and serial numbers in the online DMV system, which allows you to find out what registration fees might be, if the vehicle is in the system. Both my seller and I failed to take the step and the cost was substantial, obviously. So, as has been stated over the years: Buyer BEWARE in these kinds of vehicle transactions… the DMV computers never sleep.

Bill “MrHonda” Silver

1-2021







Wednesday, December 30, 2020

MOTO-ARCHAEOLOGY: CARBON-DATING THE '60s HONDA 250-305 TWINS

Often, when you discover a vintage Honda 250 or 305cc twin available for sale, it is lacking the title or other necessary documentation. Depending upon the state or country's requirements, you will find it necessary to "create" some paperwork for registration purposes. The first step in this process is to determine the correct year of production.

On early-'60s (1960-64) Honda 250-305cc twins, this can be pinpointed accurately, using the frame/engine serial numbers, found at various locations on the bike. You will notice that Honda's serial numbers carry a letter (or two), followed by a number (i.e. C or CA77, CB72, CL77, etc.). The "72" designation (as in CB72) denotes 250cc models, while the "77" designation signifies 305cc models (for instance, CL77). All pre-1961 (C70-71 & C75-76) engines were "dry-sump" design (separate oil tank). After 1960, the C/CB/CL 72/77-series engines were all of conventional "wet-sump" design (all oil carried within the engine).

Honda's frames were classified as either: C "Dream" (touring-style); CA or CE (US-only versions of "Dream" touring models); CB, "Super Sport" road models; CL "Scrambler" (dual-purpose); CR (production roadracing models); and CS, the "Dream Sport" (usually featuring high-mounted side pipes). The C (or CA, CE or CS)-series "Dream" models have stamped, sheet-metal frames, forks and swing arms, riding on 16" wheels (except CE71s) and equipped with "leading-link" front suspensions. All other models (CB and CL) will have tubular-type frames and swing arms, fitted with 18" (CB) or 19" (CL) wheels and conventional, "telescopic" front forks.

For 250-305cc street bikes, built before 1965, the identifying process is relatively easy. In the late '50s and early '60s, the year was often coded within the serial number (i.e. C71 59 12345); the center numbers denoting the year ( in this case 1959). Later, the first digit of the 5-digit frame (and 6-digit engine) number was used as the year code (i.e. CB72-11123, a 1961 250cc Sports model). Here's an overview of the three most popular models:

CB models: The CB72/77-series (known as 250 Hawks or 305 Super Hawks) were numbered as follows: '61-63, first digit in frame (five digits in '61-62; and six digits in '63) and engine serial number (all six digits) was year of manufacture (i.e. CB72-1XXXX; CB72-2XXXX or CB77-31XXXX frames and CB72E-11XXX; CB72E-21XXX or CB77E-31XXXX engines).

In '64, frames and engines both started with 100001 (both six digits) OR 4XXXXX numbers. The 1965 models started with 1000001 (seven-digit frame and engine numbers) and continued in that fashion. Generally, the frame and engine numbers are within 150 numbers of each other or less (often within 15 numbers), if they are the original factory pairing. One possible reason for the mismatch is that Honda would pull engines from the assembly line and dyno-test them for durability, performance, and any design/manufacturing flaws. Interestingly enough, I once owned a '64 CA77 which did carry matching 108106 frame and engine numbers; a very rare occurrence in my experience! I have noticed that, in general, the '64 engines and frames are more closely matched than for other years.

Getting back to the CB's, there are several variations, other than the "regular" Hawk/Super Hawk versions, but they were never sold in the US. The vast majority of CB-series bikes all seem to be normal Type 1 (180 degree crank) engine versions. Then, you may also find the odd CP77 frame, which may or may not be a "Police version," (which is usually called a CYP), as well as a CBM72, which has high bars, turn signals and a Type 2 (360 degree) crankshaft. The actual CP77 Police models had a different second digit in the serial number to separate them from the non-Police CP77s.

There are also "domestic" versions of CB77s with Type 2 engines. (I owned an original '62 model carrying CB77E-260474 and CB77-62-60453). Deviations from the "normal" numbering sequence usually denote models for specific countries or special applications. Genuine CYP77 Police bikes are all white and have a single, round speedometer, rather than the oval, dual speedo-tach gauges of the other models. Some Police models had 17" wheels, front and rear. Police versions have crash-bars, turn signals, solo seats, a rear rack, special lever brackets for the siren controls, patrol lights, and that great big, screaming, cable-driven (off the rear wheel) siren.

From 1965-on, there is no definitive break between the years 1965, 1966 and 1967, that I have been able to discover. Although the chrome-fendered CB models, with the "oval" tail light, were introduced from frame number 1056084 and onwards, which was at the end of the production run in 1967. The TYPE 2 aluminum fork, which appeared at CB72-1005228 & CB77-1030130, seems to be found on all '66 and later model year US bikes, according to their wiring harness tags. However, the "domestic" CP77 models featured this fork design in '65, a year before the US models received theirs. Total production for this period ('65-'67) was 56,432 (frames), so you can roughly divide that figure by three, yielding about 18-19,000 per year. If the type 2 fork bikes were all '66 models and later, then they made 30,130 1965 models and only another 26,000 more in 1966-67 combined. CB77-1056432 was the last CB77 made, in 1967.

Early models of the '61-series CB engines (and C/CA models) used a "rear breather" crankcase design and the first 280 bikes had a single-leading shoe front brake. There are three different crankshafts, three transmissions, two series of pistons, three series of camshafts, four different MPH speedometers (running in two different directions), early steel and late alloy fork assemblies, three different taillights, three different fork crowns, etc. etc. for the CB-series bikes. This is why you must always check your engine and frame numbers before ordering parts! At a distance, they all seem to look alike, but there are major differences between the years.

Sometimes, the original engines have been swapped with other CB or sometimes CL engines. I have even seen CA engines in some CB chassis! CL engines are not equipped with electric starters but can be retro-fitted with CB or CA starter motors and starter clutches, for CB installations. Or the CB engines can be relieved of their starter motors and then installed in a CL chassis! CHECK THOSE SERIAL NUMBERS CAREFULLY if you are ordering parts or doing a "correct" ground-up restoration!

CL-72 models: CL72's (250 Scramblers) were made from 1962-66, with CL77's being produced from 1965 through 1967. Bikes built through 1962 had 5 digit serial numbers (frame) and 6-digit engine numbers. Again, the first digit in the 5-digit series (6-digit in '63) is the year of manufacture. Thus, a CL72-21977 (example) is a 1962 model. It got confusing in '64, with an early bike series starting with CL72-1100001 thru 1109459 numbers, followed by CL72-4000001-4003437. The CL72-1000001 and-up numbers (all seven digit) were '65-66 models.

CL 72 models made after CL72-1008851 bikes had alloy Type 2 forks, big brakes and steel fenders and were made in late-1965, probably when the late-'65 (or probably '66) CL 77 models received their alloy forks and big 8" DLS brakes. CL72-4001597-4003196 and CL72-1000001-later models had rear brake cable anchored to the frame, instead of the cable receiver on the end of the swing arm bolt, which was seen on all earlier versions.

All 250 Scramblers, built through CL72-1107409, have "double-eye" shocks and a matching swing arm. Shocks with clevis ends on the bottom were used, thereafter, on the CL72's and all CL77 models. The slip-on exhaust silencer seems to have been introduced with '65 models. Later versions were welded onto the upper pipe. There are at least three sets of exhaust pipes/mufflers for the CL-series machines.

The CL77s: The 305 Scrambler models, CL77-1000001 to 1014495 were built as '65 models and were equipped with CL72-style steel forks and the same "small" 7" SLS Bikes after CL77-1014495 had 8" DLS brakes, similar to the CB77, but the front wheel is mostly derived from CB450 parts. The chrome fender bikes with the "oval" taillight started production from CL77-1043098 ('67 models). The "CB450" headlight, with bulb screw adjuster, began with CL77-1042143. From CL77-1033482, the rear shocks used an improved rear shock cover with a larger collar design. Longer exhaust heat shields were used from CL77-1046212 onwards.

The rubber-mounted seat and cushioned front footpegs were introduced from number CL77-1033482, along with an appropriate frame change to accommodate the redesigned forward seat mount. Front fenders and stays were changed, with the introduction of the Type 2 (aluminum) forks at CL77-1014496. A modified crankshaft with larger splines was begun at CL77E-1043132.

C/CA "Dreams": The C/CA-72/77's serial number pattern seems to be much the same as the CB-series. Of course, ALL C/CA engines are Type 2 (360-degree crank) engines. While "Dream" frames often seem to have no serial numbers, they are normally found in a location on the left side of the frame, behind the engine, below the swingarm pivot, and next to (sometimes under) the footpeg mounting bracket. It is an obscured area, often covered with grease and dirt. Many U.S. CA77's are stamped CA78, but the engines are all marked CA77. '61 and early-'63 models had different styling on the tank and chrome side panels, as well as a myriad of other smaller details concerning the handlebars, cables, fenders, seats, plastic side covers, etc. The CA78 models are often called “Late Dreams.” “Early Dreams” differed between the 250 and 305 models, mostly with the fuel tank designs.

All Dreams, through 1965, used a tall, thin, wide 12v battery (6v on dry-sump models), which was then superseded to the CB-type battery. The frame's battery tray, tool tray, and side cover were all modified to accommodate this design change. Seven-digit serial numbers commenced in 1965 on Dreams, too.

Almost all models, sold outside of the U.S., had turn signals (winkers) factory-installed. There are several different versions of "winkers," which correspond to the legal requirements of different countries. Sometimes, you will find 250-305 models registered as '68-69 models, but remember that they ceased production in '67, to make way for the CB/CL 250-350 models introduced in 1968!

The final way to date most complete, original bikes (that haven't had a wiring harness fire, modification, or some similar misfortune) is to check the harness between the steering head and the battery connectors (usually somewhere under the fuel tank) for a small white tag, attached to the outside of the harness wrapping. It will usually show both the part number of the harness, often including the model and THE DATE! It is the date of manufacture of the harness, but almost always corresponds to the date of the bike, too, but we have found exceptions to that rule, as well.

Well, so much for a "brief" history of dating Honda "big twin" motorcycles, produced in the early to mid-'60s. Starting with the 1970 models, U.S. regulations required manufacturers to show the month/year of manufacture of all motorcycles. This ID tag, which includes the frame serial number is usually found on the right side of the frame's steering head. Since 1981, the 17 digit VIN codes have been standard on all motorcycles. They can be decoded too, but that is another story.

Bill Silver (aka MrHonda)























Sunday, December 13, 2020

The Classic Honda used bike minefield… CB/CP77

The line from Forrest Gump that goes, “My mom always said life was like a box of chocolates. You never know what you're gonna get.” certainly applies to prospective purchases of vintage Honda motorcycles.

Unless you are buying from the original owner who has all the service records and a list of mods or damage repairs, you can never really be sure about just what you will find when you set your eyes on that rare bike that you have been lusting for during the last few years.

Case in point: I was helping a friend try to track down a black Honda CB77 Super Hawk to match is original black CB160. I had recently helped him market his CB450 Black Bomber so now he was hunting a black Super Hawk. I had sold a couple of really nice bikes in the past two years, but it seemed like very little was out for sale in the past few months. Hoping to avoid a blind purchase of some bike that was far, far away, an “opportunity” passed though my searches that appeared to be the black CB77 that my friend was seeking right here in San Diego County.

In the photos, it certainly appeared to be a “flat bar” CB77 of about 1964-65-ish vintage, but it was listed as a 1965 CP77 instead. The production CP77 (non-Police bike) models were never sold in the US, but they seemed to have been offered in Canada back then and a few of them migrated down to the US over the years. The model causes confusion as it might be considered the “street bike” version of the CP77 (actually CYP77) Police model. Again, a few Police models did go to Canada, but never to the US. The non-Police models look like standard CB77 Super Hawks, except that they have very high handlebars, turn signals, a sidestand, solid footpegs and the tail light that was only seen on the 1961 CB72-77s in the US.

Looking at the photos of this bike, it was obvious that the handlebars had been changed, the original turn signal switch was missing as were the rest of the winker parts. The side stand was not present and the tail light appeared to be the generic CB72 taillight used on 1963-66 models. So, in essence, the bike was reconfigured from the original CP77 roots to an early-style CB77 look.

Some of the current owner’s history was shared in that he had reworked the front forks due to some accident damage, had given it a good tune-up and may have replaced the tires. Unfortunately, the tire choices were 3.25x18 front and 3.50x18 rear which will ALWAYS upset the bike’s ability to stay steady on the centerstand.

I was requested to check the bike over prior to the sale transaction, which took me 50 miles from home. The bike presented itself as an unrestored model, which had a few dings and chrome pitting, but seemed overall a solid base to work from for someone who was willing to spend some time and money to get it back towards original condition again.

I started the engine, which sounded healty and firing on both sides evenly. In retrospect, I should have taken it out for a quick spin to check it for clutch slippage and/or clutch release issues.

After some wrangling, the owner and buyer made a deal and we loaded the bike into the back of my Tacoma for drop-off in Solana Beach, CA. By the time I returned home there was a message about what to do with the bike to get it serviceable and closer to stock CB77 shape. Obviously, the tires were top on the list and replacement rubber in the stock 2.75x18 and 3.00x18 sizes were ordered up.

The next question came up about how the steering lock works. At first the key was sticky and the lock wouldn’t move properly. With a few squirts of graphite lube, the steering lock was working fine, but the place where it was supposed to lock into was not present. A close-up photo revealed that the whole steering lock portion of the frame was cut/sheared off, perhaps in an accident. I can’t say that I have ever seen this happen before on a Super Hawk, as the steering stops for the stem contact the frame down behind the steering lock bridge portion. It was a mystery and a problem not easily remedied.

After a batch of parts had arrived, I arranged to swing by the owner’s home and dig into the project, starting with changing out the tires. The tires dates were back in the early 2000s and their oversizes caused extra difficulty in removing them from the rims. I started with the rear tire and once it was removed, there was a good bit of rust corrosion in the rim bead area and around the spoke holes. I knocked off the worst of it and wire-brushed the loose bits. I wrestled the new tire back on and prepared to install the wheel again, but saw signs that the ends of the cotter pins on the rear sprocket castle nuts were hitting something. There were signs that the cotter pin ends had been hitting the inside of the chain guard bracket, which also showed signs of being rewelded previously.

An even closer look revealed that the rear shock bolts had been installed backwards so the thick outer nuts were very close to the sprocket nuts. The shocks required removal and a 180 degree turn on the bottom to get the threaded portion of the lower clevis set properly, so the shock bolts, which have thin heads, were installed with them pointing outwards. The previous owner had commented that he had to put a longer chain on the bike to allow the rear wheel to be moved further back enough to clear interference with the forward edge of the rear fender, next to the swing arm. That sort of made sense, but then I discovered that the rear sprocket was stamped 32 instead of the stock 30 tooth markings. The stock 94 link chain had been included with the bike’s spare parts, but obviously wouldn’t work with the big tire combo.

I had brought a spare pair of new aftermarket chain adjusters to help brighten up the rear axle area, but one of then turned out to have stripped threads for the adjuster bolt. It is amazing how much time is spent sorting out all the little issues like these when you are wrenching on an older Honda bike with a little known history.

Once the rear wheel was reinstalled, it was time to move onto the front tire replacement. The first thing to notice was that the pinch bolt for the left front axle case was an Allen bolt, instead of the normal bolt with a 14mm head. Secondly, the bolt was loose in the threads. The bike had to be jacked up in front off of the starter motor, but the bike was also supported by a 2x4” board beneath the center stand feet to give the bike enough room to pull the over-sized front tire out of the forks and front fender. I had to remove one of the fender stay bolts to allow the wheel to clear the the fender’s cable stays. Apart from pinching the inner tube (there was a spare, thankfully), the front wheel went back together okay, except for installing a few front brake cable. The cable adjusters were mostly used up in getting the brake to adjust properly, which turned out not to be worn out brake shoes but the brake linkage arms had been installed one spline off from where the punch marks were shown. The wheels will be coming off again in the near future so the fenders can be removed and repainted, so the brake cam/arm issues can be addressed then.

The last few jobs for my 4-hour stint included an oil change, change the spark plugs and check the ignition timing. The first two tasks were easy enough but the last one brought a shock to me when the dyno cover was removed…

Instead of the typical CB72(L) rotor marks on the face of the rotor, I was faced with C72 marks which can only come with the use of a Dream or Type 2 engine CBCL engine. Beyond the surprise of seeing the wrong rotor installed, instead of a central rotor bolt to attach the rotor to the crankshaft there were two nuts, double-nutted on a stud! I have NEVER seen this adaptation done to a CB77 engine before or any other one, which leaves one to wonder, whether the end of the crankshaft threads were damaged previously and this was some kind of creative repair to keep the bike on the road.

The rotor had some black marker hash marks 180 degrees from the only stamped T and F marks on the rotor, which appeared to be properly set. I hooked up a dynamic timing light to the ignition and verifed the right side marks first. Then I used the black line mark as a hopefully accurate mark to set the left side ignition timing. The marks showed that the timing was retarded a few degrees, so a small adjustment was made to correct the error. The engine idles evenly and sounds like it has good compression. There are no signs of smoking, but there is no known history of what has been done to the engine beyond what has been discovered.

A quick ride around the neighborhood revealed that the transmission didn’t want to shift back into neutral when the bike was at a stop in gear. This is almost always due to someone removing the thin wire retainer rings from the clutch hub. The retainer wires help hold the first few clutch plates on the hub, which helps the rest of the clutch pack separate and release it’s grip on the transmission shafts. When the engine torque is removed from the transmission shafts, the shift selector can do its job of selecting whatever gear you wish, including neutral.

So, the next few upcoming hours will include removing the clutch cover, inspecting and cleaning the oil filter, checking what appear to be excessively strong clutch springs, looking for missing retainer springs and then popping in a new shift shaft seal while the cover is off.

If that doesn’t reduce the amount of clutch lever force currently experienced, then the kickstarter cover will be removed and a new clutch adjuster will be installed to reduce the amount of thread slack between the adjuster and clutch lifter arm threads. Reducing the slack translates into increasing the amount of clutch pushrod travel which separates the clutch pack more completely.

$100 worth of gaskets, seals, chain adjusters, clutch springs and a clutch adjuster have been lined up for the next round of repairs, hopefully the last for awhile.

Round Two….

The priority task was to address the clutch release issues, so the right side exhaust was removed to allow the kickstarter cover to be taken off to inspect the clutch adjuster threads/slack. Pulling and pushing the clutch lifter arm in and out of the clutch adjuster showed excessive slack/play between the two parts. The clutch adjusters are made of aluminum so the coarse threads are eventually worn down from repeated cycling of the clutch while riding. This bike was showing 10k miles and the parts looked original, so a fresh clutch adjuster was installed.

An unfortunate surprise when the kickstarter cover was pulled back was a splash of motor oil that had pooled below the crankshaft/starter clutch. Using a flashlight to check for oil trails, didn’t show anything that was really active on seals that were installed in the cases. So, that left the little seal that installs in the center of the starter clutch hub as the probable cause. Ordinarily, I would pull the rotor bolt and use the 16mm special tool to remove the rotor to check the starter clutch roller springs and the condition of the oil seal on the starter clutch hub. In this case, the C72 rotor that was looking back was being held in place by a stud and nut/washer instead of the normal rotor bolt/washer. As this was a house call visit, I didn’t have all the tools I needed to go further in this direction, so I had to wipe up the oil mess and leave it alone for the moment.

The new clutch adjuster was greased and installed, then the kickstarter cover reattached. Pulling the clutch lever felt about the same as before. So, the next step was to go to the left side, remove the exhaust system and footpeg/linkage to allow the clutch cover to be removed. The cover screws all came out easily and the cover came off with the gasket intact for a change. Pulling the clutch spring bolts out revealed what appeared to be the “white springs” which are stock for 305s of that time-frame. That was puzzling, but pulling the the plates off and looking carefully showed the probable cause of the clutch drag problems. I was somewhat surprised to see that the oft-removed steel retainer wires, which hold the first few plates in place, were still in place.

While the friction plates looked normal for used parts, the steel plates showed all the signs of an earlier “stuck clutch” condition where the plates had been pressed together for many years of storage, then adhered together transferring some of the friction material to the steel plates. It generally looks like a combination of rust and friction material that is left behind when the clutch is jarred loose by running the engine with the clutch lever pulled in until the clutch plates get unstuck.

When this approach is used, the leftover material on the steel plates keeps dragging against the adjacent plates which prevents a clean release of the clutch pack and causes difficulty in finding neutral when the bike is in gear and stopped at a light or stop sign. I had brought a set of steel plates that were NOS and rather than try to clean the old ones, we popped in the new set, reassembled the clutch plates and springs and then checked the clutch release function. You can watch the clutch separate by pulling the clutch lever in and kicking the engine over. When the clutch releases, you can see and feel the disconnect between the engine and transmission. It appeared to be working correctly, so we put it all back together again, refilled the crankcase and fired the engine back up again. Even driving the bike just a few yards in gear, then selecting neutral yielded the little red neutral light lighting up with ease.

So, the clutch release issues were finally solved and the bike is now driveable in traffic without struggling to get the transmission into neutral with relative ease. The total labor time ran close to 3 hours in wrangling all of the parts for the clutch release problem. That’s good news for now, but that oil leak is still present and will need to be addressed sooner than later. The owner wants to remedy the loose fork covers by replacing the little rubber ring packings that sit down inside the fork rings. That requires removal of the front wheel, fender, handlebars, fork bridge and all the related parts. So, that is the next round of labor to hopefully complete the major repairs and complaints for this 55 year-old classic Honda Super Hawk.

Round Three

This time, we had to resolve the mystery of the C72 rotor mounted on the end of the crankshaft with what appeared to be a stud instead of the conventional rotor bolt/washer that screws into the end of the crankshaft. I sourced a new CB72 rotor from my dwindling parts supplies, loaded it with new springs, caps and rollers ready to install, along with a seal kit to remedy the previously discovered oil leak issues. I brought a 3 jaw puller to attempt the rotor extraction and once it was in place, a few hard turns of the tool’s shaft brought satisfaction as the rotor flew off the end of the crankshaft, scattering little starter clutch springs, caps and rollers around the floor. With the rotor removed, you could see that the oil seal for the starter clutch hub was half-way falling out, which accounted for the oil leak. The main crankshaft seal seemed to be holding up okay, so we just replaced the clutch hub seal with a new one and reassembled everything with the new rotor. The mystery of the end of the crankshaft was resolved when it was revealed that a bolt had been welded into the end of the crankshaft! I guess no one will ever know why the previous owner took that path of repairs, but the end of the crankshaft still runs true, so it is what it is and it is good enough for the future.


 

Bill “MrHonda” Silver

12-2020

Saturday, October 24, 2020

Honda… 1967

 American Honda was running into difficulties in 1967, at least with the US operations and sales. They had amassed a huge inventory of slow-selling models and financial challenges almost lead to their downfall in the American market. Honda’s engineers were also tasked with working on a new car line (N600-Z600 sedan/coupes) had just pulled out of Grand Prix motorcycle racing, and were diving into automobile GP racing, so resources were scattered out everywhere.


Honda had been selling basically the same motorcycles for 7 years, with few updates. The US line-up for 1967 was the whole line-up of now-obsolete push-rod-50cc Cubs (Honda went to OHC engines in 1965 with the S65), a transition from the CA95 to CA160, CB/CL160 twins, 250-305s and the blossoming CB450, which finally got a 5 speed transmission. Honda reportedly had imported 100,000 50cc Cubs during the early years. At $245 the Cubs few out of dealerships initially, but then languished as more powerful machines were offered.


While Honda continued to churn out old models, their rivals were gaining a big foothold in the US. Yamaha, Suzuki, Kawasaki and Bridgestone (which closed in 1971) all had innovative models, many with 5-speed transmissions and colorful paint schemes. The snappy performance of the 2-stroke engines gained many fans, especially due to their lightweight engines, which had few moving parts in comparison to Honda's more complex but sturdy four-stroke machines.


Seeing the handwriting on the wall, Honda began to move in the direction of cosmetic and mechanical upgrades to all of their models. Looking at the 250-305cc models, there were just a few visible changes, like alloy forks on the CB72-77s and restyled seats with upturned forward edges. Honda changed the transmission and crankshaft splines for easier manufacturing and added on some chrome fenders and an oval tail light to the Super Hawks.


Honda Dreams were mostly unchanged after the switch to “late style” models in 1963. Honda swapped out the old, tall, thin batteries for the short, fat CB77 batteries in 1966, which continued until the end of production. The oval tail lights are shown in the parts books for the 1967 models, but few have ever been seen in the US.

The buzzy Honda CL77 305 Scramblers had an engineering makeover, including the transmission splines and a rubber mount update for the seat, rear fender, muffler, fork ears and footpegs to improve rider comfort. The 1967 models also gained the “oval” tail light on the end of their production models, first on the standard silver-painted fenders, then with some late-release chrome fender models which also came out with the first of Honda’s Candy Blue/Candy Orange paint schemes.

There were other little detail changes like cleaned up carburetor bodies which had vestiges of never-used power jet casting features removed. The horns were changed to cheaper plastic versions and even the tappet covers had a different shape but never had a revised part number.

The “041” oval tail light assembly was sourced from a small C50 step-through model, but applied to all of the 1967 machines. For models like the SS125A-CL125A and the new 5-speed CL175K0, which were only sold for 3 years, the shape of the tail light defines whether the bike is a 1967-68 or 1969 which had a new taillight design featured on the CB750K0 machines.

For new models like the CB/CL350s and carryover CB/CL450s the tail light shapes were oval for 1968, then followed by the enlarged CB750 types.

One of the major changes for Honda in 1967 was the switch from JIS tread pitch to ISO standards. This changeover leads to many difficulties for models which were instituted before 1967 and continued afterward, like the S/CL90 models, CT90, and the CL1750K0. When looking at the microfiche parts illustrations and part numbers you see the transitions on fasteners and any other parts with threaded holes during the period.


The JIS to ISO changes affected 3,4,5 and 12 mm screws/bolts

(SIZE OF BOLT OR NUT) PRESENT JIS MODIFIED JIS (ISO)

3mm                                          0.6                     0.5

4mm                                          0.75                  0.7

5mm                                           0.9                  0.8

12mm                                         1.5                  1.25


The size of the bolt heads was also revised

(SIZE OF BOLT OR NUT) PRESENT JIS MODIFIED JIS (ISO)

3 mm                                      6 mm                  5.5 mm

4 mm                                      8 mm                  7 mm

5 mm                                      9 mm                  8 mm

6mm                                       10mm                  10mm

8 mm                                      14 mm                  12 mm

10mm                                      17mm                  14mm

12mm                                      19mm                  17mm

14mm                                      21mm                  19mm

16mm                                      23mm                  22mm

18mm                                      26mm                  24mm

20 mm                                     29 mm                 27 mm


All of these changes affected even the handlebar switch screws, as the transition continued. The rare NOS handlebar switches that come up for sale for most models, including the 250-305s all have JIS-threaded screw threads. Unfortunately, JIS threaded fasteners are quite hard to find anymore, so you are faced with having to re-thread JIS holes to ISO for these parts, as well as the 5mm screws on 250-305 point covers and dyno covers.

 Things began to start looking up in 1968, with the release of the all-new 350cc, 5-speed twins, the 5-speed 450s, and even the new CL175s now came with 5-speed transmissions. Most all 1968 models sported metallic paint schemes, more chrome and a new sense of purpose as they moved into the end of the 1960s.

Bill “MrHonda” Silver

10-2020


Tuesday, August 18, 2020

Small part, big confusion…the 250-305 kickstarter pawl

 There are three little parts on the end of the kickstarter shafts of ALL 250-305cc twins from the 1960s. They are:

SPRING, PAWL product number: 28228-250-010



PAWL, SPINDLE product number: 28255-250-020


PIN, PAWL product number: 28256-250-000


Notice that the center codes of these parts is 250, which comes from the first generation dry-sump engines, which were built in 1957-60.


       Kickstarter shaft with kickstarter pawl and pin shown in correct installation order.

These parts are responsible for the kickstarter arm engaging the transmission’s low gear, which is connected to the crankshaft via the primary chain. While the kickstarter shaft only moves when the kickstarter lever is depressed, the kickstarter pawl/spring/pin parts are all actively engaged when the engine is running. The pawl is pressed into the inside features of the transmission low gear by the spring and pin, which stabilizes the spring as the assembly rides up and down inside the transmission gear.

For the kickstarter function to occur properly, several things have to be properly aligned and in good condition.

1. The low gear is supported on the kickstarter shaft by a stepped bronze bushing, commonly called the “low gear bushing.” This bushing is supporting two gears with a step in the middle to separate the two gears on the shaft. Over time, the bushing wears down, causing the low gear to wobble on the bushing. Also, the little step ridge on the center of the bushing gets worn down laterally, eventually wearing the ridge completely off of the center of the bushing surface. When this happens, the low gear is both wobbling on the bushing’s exterior and is also allowed to move laterally towards the adjacent gear and away from the kickstarter pawl.



2. The kickstarter pawl has a bit of “float” in the end of the kickstarter shaft, but needs to be fairly squared up inside the low gear’s inner engagement features. If the low gear gets too cockeyed and wobbly on the bushing and kickstarter shaft end, then the kickstarter pawl can’t fully engage the inside of the low gear and the whole mechanism “slips,” instead of engaging the engine properly.



3. Because the kickstarter pawl is always engaged, operating basically as a one-way clutch, the edges of the hardened steel pawl eventually wear down, causing another reason to create slippage when you try to kickstart the engine. The little pawl pin pushes up on the back side of the pawl to keep it engaged with the low gear teeth. The pin is spring-loaded by a tiny coil spring that drops down into the hole in the end of the kickstarter shaft. After many millions of cycles of up and down for all three parts, they eventually wear out. The sides of the spring can wear flat and begin to grab the outside of the pawl pin and the two begin to accelerate wear together, as they do their best to support the pawl itself. The tip of the rounded pin begins to flatten out, as well. In high-miles engines, the “teeth” that engage the kickstarter pawl on the inside of the gear also wear down, so they can’t hold the pawl end properly.



4. When maintenance is left undone, due to lack of oil changes, poor engine tuning and other factors that put additional stress on the kickstarter pawl system, eventually it fails completely. Because these parts are part of the transmission, the engine cases have to be split in order to replace the worn and damaged components. In some cases, either the end of the kickstarter spindle that supports the pawl will break off and/or the roller bearings that support the transmission gear on the opposite end of the shaft will wear through the hardness of the shaft surface and begin to dig into the shaft. 

Instead of rolling smoothly, the transmission gears start to engage the shaft during on-off throttle conditions. What happens is that the kickstarter shaft begins to swing back and forth, while the bike is being ridden. On a CB72-77, the kickstarter arm can come into contact with the rider’s shins on the right side, in a surprising display of force, as the kickstarter arm goes forward on its own, then whips backward towards your leg.

5. Another wear point in the transmission, being affected by the kickstarter pawl is the 14mm end spindle bushing surface face. The continuous movement of the pawl pushes up against the edges of the 14mm bushing causing the pawl to dig a trench into the bushing face. This adds more end play to the already sloppy transmission gears/shafts and can cause the gear dogs to lose their engagement contact surfaces. When this happens, the transmission jumps out of gear and when this repeatedly happens, the transmission gear dogs get rounded off causing even more shifting difficulties and damage to the transmission components.



In more than a few cases, while doing repairs on used 250-305 transmissions, has lead me to discover that a previous repair attempt has left the kickstarter pawl improperly installed. On a recent CL77 transmission repair, the bottom end, which had been apart twice, had the pawl installed backwards, so that the sharp edges were engaging low gear, just barely. It was “working” to a degree, but obviously it wouldn’t have lasted for a lot longer. The owner reports that the transmission repairs, including offset cotters, now shifts very smoothly and the kickstarter works perfectly.


                                             Incorrectly installed kickstarter pawl!


Bill “MrHonda” Silver

8/2020

Image credits to cmsnl.com and Cappellini Moto (spindle bushing), eBay sellers and MrHonda.