It’s all in your head… 250-305 cylinder heads.

For mass manufacturing, simplifying the production process yields more products at a cheaper unit price. As Honda ramped up production from the early days of J-Benly, SA/SB-ME-MF singles, their goal was to build a reliable and punchy OHC twin, which was indeed inaugurated in 1957. Honda designers must have decided that making thousands of little valve seats for the cylinder heads could be replaced by a cast-iron cylinder head “skull” which incorporated the combustion chamber, including valve seats along with the spark plug hole. The cast-iron skull was then set into another mold in which was poured molten aluminum, fusing the two dis-similar metals together into a single unit. From there, valve seats could be easily cut and the combustion chamber either left in the 250cc-sized hemispherical shape or the edges were chamfered out to match the step up from the 54mm 250 piston size to 60mm enlargement for the 305cc displacement.

As brilliant as the design was for manufacturing, the heads did have a tendency to have the skulls work loose from the alloy castings, causing oil leaks around the edges of the spark plug holes.

This discussion will revolve around the “wet-sump” 250-305 engines which began production in 1960 and carried on until 1967. The earlier dry-sump engines are in a different class of design and application and are seldom seen in the US. When Honda came to the US in 1959, they offered the CE71 and some various 250-305cc versions of the dry-sump (separate oil tank supply) bikes, but swiftly moved into the newly-designed wet-sump types.

The 250-305 Dreams were introduced in 1960 in the new wet-sump format, followed by the CB72-77 Super Sports in 1961. The range was extended in 1962 with the newly designed CL72 250cc Scrambler.

For the first two years, the cylinder heads were offered with tiny 10mm spark plug holes. In early 1962, the heads were machined for the commonly seen 12mm (NGK D8HA spark plugs) and that continued throughout the rest of the production runs for all models.

Visually, the early heads were most easily identified by the U-shaped machine work done between the exhaust ports on the cylinder head fins. In 1965, there were numerous detail changes to the engines, including the elimination of the machining step for the fins, as they were now cast in a clean V-shaped design.

                                                                1965-on V-pattern head

1960-64 U-fin cylinder head.

People often question about the interchangeability of the cylinder heads across the three models. To manage the number of parts needed to build these engines, all the cylinder head castings are the same to allow for cross-building of the various engines. Apart from the single intake port Dream heads, all the dual port heads will interchange between Scramblers and Super Hawk models. Early Dreams had smaller exhaust valves, which were upgraded to the CB series exhausts in 1962. For 250-305 dual port heads, they all share the same valves, despite the difference in displacement sizes. There is a slight difference in the intake port size for the 250 heads, where the 22mm carburetor insulators match up to the intake ports.

Honda was able to use the same castings for the dual port heads, as far as the combustion chambers are concerned. The 54mm bore size of a 250, requires a tight hemispherical combustion chamber with a small squish area at the edge of the piston crowns. The same castings used for the 60mm 305 engines require a beveled chamfered machine cut to allow for the fitting of the larger pistons.

                                                      Combustion chamber for the 250cc engines

                                                          305cc combustion chamber

These cylinder heads do not use valve stem seals, rather there was a thin air passage drilled into the head that matched up with some cross-drilled intake valve guides. This system was thought to break up the oil film on the intake valve stems, reducing the tendency to suck engine oil past the stems and guides into the combustion chambers. Remarkably, this system seems to have worked efficiently for all the years, until 1967. Honda decided to eliminate the whole system just in the last year. The last generation engines don’t seem to be more prone to using oil than the previous types, however.

So, in conclusion, the main difference between 250 and 305 cylinder heads is the machine work on the edges of the combustion chambers. Heads are generally interchangeable between the various versions of the engines. Considering the engineering challenges faced in the late 1950s, to build motorcycle engines that could rev up to 9k plus in a world of plodding, low-rev OHV designs from European/British companies, the speed of manufacturing of components led to the dominance of Honda in the world of motorcycle manufacturing.

Bill Silver

aka MrHonda

www.vintagehonda.com

10-2024

MrHonda dodges a scammer…

What started out with an SD Reader ad for my former Pink Panther CB77 Honda (now restored to Silver and Scarlet Red) culminated in an attempt to scam me out of at least $980. The SD Reader ad had my phone number, so when I got a text message from someone wanting to buy the bike, I was not too concerned. In fact, I texted him a photo of the “Hot Rod CB77” bike that is also for sale and he said he would buy it for $300 less than my asking price. It appeared that I was going to cash in on a double sale and put some cash in the bank, but in the end, it was just a scam.

Initially, the man messaged me that his “PA” had made a mistake and added an additional $1500 to the amount, which was supposed to go to the shipper. He asked me to give those funds to the shipper when they arrived to pick up the bike. I agreed, as long as funds were secured in the bank.

A couple of days later, a check arrived with the name of a construction company. To that point, this man had never introduced himself, so I had to ask his name. Finally, I did a search on the business name on the envelope and found just one name in Virginia where the envelope was sent from. The man said he was working in Georgia, which is why his phone number had an Atlanta area code.

I took the business check to the bank and asked if they could verify the funds. Apparently that is not easily done, so I was told that if it was deposited into the system, there would be some indicators as to whether the check would go through or not. The check was deposited and initially there was just a couple hundred dollar release from the $11,800 business check I received.

I became suspicious looking at the check, which had a different business name from a corporation in NY. The bank it was drawn on was in Illinois. So, I was looking at a guy who was currently in GA, but living in VA, with a bank account in IL and a master account in NY. It didn’t really sit right with me, but I was willing to let it play out until the check cleared.

After 2 days, there was a partial release of $5k. I asked the bank if this was a good sign or not, but was advised to let the check go all the way through to verify the funds.

The next day, I started getting text messages asking if I had various ways of transferring funds, like Venmo or PayPal. I only use PayPal but the current balance was zero. Then, he said that he had promised his shipping partner friend a $980 amount for some kind of services and could I send that “right away.” This was beginning to sound like a classic Nigerian 419 scam. Finally, I was asked if I could send a postal money order to his friend that day. I was on the road to my chiropractor appointment which is an 80-mile round trip. I turned off my phone and went to my appointment and headed back home again.

When I turned the phone back on, there was another message asking if I was going to make this payment to his friend. He had never offered the name of his friend or how to contact him with funds, but I sensed that the game was up after that message. I told him that I was waiting for the check to clear completely and then the messages went quiet.

The next morning, I was greeted by multiple messages from my bank saying that I was overdrawn in my account with a negative $2k balance. The “item had been returned” so the $11,800 amount was not valid, plus the hold on my account was reversing my balance from plus $4k to a minus $2k. I was advised to “fix the problem” ASAP or an overdraft charge of $36 was to be charged and it would certainly affect my credit score.

That morning, my friend Bill had driven down from Orange County to help me finish putting his SL100 project back together. I figured that I had plenty of time to finish the bike and then get to the bank to sort things out. Well, of course, the bike took 7 hours (including lunch) and the time was getting short to get to the bank.

In the interim I received another flurry of emails from the bank, stating that the overdraft charge was reversed and my account was back to $4k again. I don’t know if this was an automatic system re-balancing or if someone got directly involved at my branch. Anyway, everything was restored and no further action was required.

When I texted back to the man, telling him that it was a scam, as I was beginning to suspect, he denied it and said I was lying. I copied the bank statement section of my account and texted the line that said “$11.800 item returned.” Then I told him that I was filing a scam report to the BBB, which I did and sent him a copy from the BBB system recognizing the report. Then, I blocked his phone number.

I’m sharing this with you all, as there is a proliferation of scam attempts in the Facebook forums and with increasing spam messages to my email addresses. Do NOT send funds or accept fake checks, no matter how good they look unless they clear the bank completely. Do NOT advance any of your funds to the buyer before the check clears.

The internet is turning into a Wild West show where anything goes now, in the name of financial gain at the expense of the unsuspecting public. With huge data breaches revealing email addresses, phone numbers, account numbers and social security numbers, everyone needs to be on high alert for those people who want to make a buck or a thousand at your expense.

I am musing whether to add this man’s name to the story at the moment. If you want to know who it is, contact me directly.

Be careful out there, folks….

BTW: the bikes are still for sale...

Bill Silver

aka MrHonda

www.vintagehonda.com

All coiled up, but unable to strike…

With the decreasing availability of OEM Honda (and other makes/models) ignition coils, the only alternative appears to be the Chinese-made copies of single—and dual-output ignition coils that flood the eBay market listings.

I recently had an exchange with one eBay seller about this listing:

High Voltage 12V Ignition Coil For Honda CS90 CL125S CL100S S90 SL90 XL100

I pointed out that none of these models use a 12v coil, but the replies were vague and unhelpful.

This listing: 

6 Volt 1 Ohm Ignition Coil Dual Spark Plug Output for Honda And Others 24-72454 shows the application chart including CB92, CA95, CA160, and CM400T! I doubt that it will last more than a few minutes, as a 1-ohm coil is designed for electronic ignitions.

Case in point:

Recently, my friend Steve P. was finishing up his wonderful restoration of a 1961 Honda CB92 and Hs purchased an aftermarket coil from an eBay seller. After re-checking the cam timing, ignition timing, carburetor jets and metering circuits, he was unable to get the bike to fire up at all. I made the usual suggestions about the basics, which he checked out thoroughly, but still no joy when he hit the starter button, even with some starter fluid sprayed into the intake.

I agreed to come by his place and check his work and the bike over, looking for any concrete reasons why his restored engine and bike were stubbornly inert. The compression tested out to about 100 psi, equally on both sides. We verified that the cam timing and valve lash settings were all correct. The point gap was .014” and they were opening at the F mark.

With the spark plugs still out after the compression test, we grounded the plugs for a spark check. Initially, there seemed to be a strong spark, but in repeated cranking the spark became erratic and finally pretty much quit altogether. One thing that can upset spark creation is a failed or disconnected condense. But when it has a problem, the points will arc heavily during cranking or engine operation attempts. This was not occurring in this instance.

Having checked and eliminated the main possible culprits and noting the diminishing spark output, I pulled the coil primary leads off for an ohms test. The ohms test for the supposed 6v dual-output coil read out at 4.5 ohms. That is a reading expected of most vintage Honda coils that are of the 12v variety, but not for 6v types. When we checked his removed OEM coil, it tested out at about 1.5-1.8 ohms, which is what you would expect from a 6v ignition coil.

                                                        A genuine CB92 ignition coil. 

So, what was happening is that the 12v coil, being fed a diminishing 6-volt supply, was dropping lower with each electric starter test cycle until the voltage dropped below the cut-off limit. The higher resistance of the aftermarket coil curtailed the spark output on a steady decline until it ceased.

It’s easy to see an initial spark at the spark plug on a quick check and assume that it should be enough to run the engine. In observing the decline in spark activity through prolonged engine cranking, you get a truer picture of what is happening. This is a vital clue to troubleshooting an ignition system issue.

In an earlier blog story, back a few years, I wrote about buying a CR93 street bike tribute bike, based on a CB160 chassis with a 5-speed CL175 engine installed. Ironically, I had owned the bike and sold it at a swap meet event in N. Cal. The tank and seat were actual CR93 components fitted to the CB160 chassis. I could see that a great deal of detail work and restoration work had been done to the bike, during its surprise, last minute entry at the Las Vegas Auction. I felt compelled to buy it back and did actually win the auction in the end. https://www.mrhonda.guru/2017/03/the-beast-within-beauty-cr93-replica.html for the story.

The bike had not run recently, so I went through a basic check to see how the basics were doing before trying to start it up. The carbs were cleaned and one float was found to be sinking. Once the carburetion was dialed-in and ignition timing checked, the bike fired up quickly on a fresh battery, but it wouldn’t run more than a few blocks before it began to misfire and finally quit altogether. Backtracking over my previous work and rechecking all the obvious causes, I finally realized that the spark to the plugs was becoming erratic, after just a few minutes of operation.

The CB160/175 series of bikes are all equipped with 12v charging and ignition systems. Finally, I noted that the ignition coil was an aftermarket copy and checked the primary resistance. It was about 1.8 ohms, which is something that you would see for a 6v ignition system or in some cases bikes equipped with electronic ignition systems. Most full electronic ignition systems use coils in the .3 to 1.5 ohm range. When these coils are substituted on a 12v system using points and condenser, the high current draw will burn out the primary coil windings pretty quickly.

Sure enough, when I replaced the coil with one of the 4 ohms range, the bike started immediately and continued to run for an extended period of time without any mis-firings or performance issues. Recently, a customer bike came in with perfomance problems and on a single-cylinder vintage Honda machine and when the coil was checked, it too, had a 4-ohm coil instead of something in that 1.5-1.8 ohm range.

In looking at some of the various eBay listings for aftermarket coils, few, if any, have ohm specifications listed. Because motorcycle coils come in just a few sizes and mounting dimensions, it seems that the sellers are pushing out products that are inappropriate for the desired applications. Typically, you will see the same photos of the same coils listed by various named eBay vendors who are either all working together or all getting the same products from a few manufacturers in China.

Asking questions about the specifications is often a fruitless endeavor, as they are not tech-savvy vendors. They seem to take your questions and then refer to the suppliers in China. I imagine that there are translation difficulities all around, which make finding out the details of a component difficult or impossible.

So, all I can say is BEWARE of aftermarket products, especially in the category of ignition coils. DO NOT buy from one who is unable to supply the correct ohms specifications for their products. Their cheap pricing is enticing, however you may well find yourself scratching your head for hours wondering why the bike won’t run even though you have changed the whole ignition system.

This one small detail makes all the difference in success or frustration when trouble-shooting the cause of engine performance failures. Once Steve replaces his coil with one of the correct primary winding impedance (or puts the original one back in place), the bike should fire up properly and he’ll be a happy man. I feel that this is an important issue that needs to be remembered in times of frustration and confusion after a bike build or repair.

Bill Silver

aka MrHonda

www.vintagehonda.com

There’s always a reason… find it! CL175 2.0 to completion.

Welcome to MrHonda’s mystery hour, where we delve into the unexplained behaviors of vintage Honda motorcycles, after normal repairs have been completed. In this edition, the subject in question is a 1969 Honda CL175K3, which had an engine overhaul and carburetor cleaning. The engine starts up easily but then loads up the spark plugs quickly with excess fuel.

Spark plug fouling at idle is generally attributed to either the wrong-sized pilot jets, high float levels, blocked air bleed passages at the carburetor inlet ports, incorrect ignition timing, high resistance spark plug caps, defective spark plugs (fake reproductions), low spark voltage due to failing coils, weak condenser, incorrect cam timing or aftermarket parts which are not made to OEM specifications.

Background information: The engine was brought to me in pieces for a rebuild, including the replacement of the kickstarter shaft. The cylinders were still on STD bore sizes, so the bores were honed and new rings were installed. The original valves were re-seated and all new seals and gaskets installed. It was pretty much a standard engine rebuild.

Once installed, the engine was started up, sounding rough as if it was running very rich at idle and just off-idle. It fuel-fouled the spark plugs in just a matter of minutes. The carburetors had been disassembled and cleaned, noting that one of the slide needles were marked D2, which indicates that they are from Keyster carb kit. The idle jets were also from the kit and marked #38, which is correct for this engine series. The main jets were marked #92, which is stock, but I have had issues with the accuracy of the kit parts in many cases. The bike is a Scrambler, with left-side high pipes, which have to be removed or at least loosened up so that the left-side cover, air filter and carburetor can be removed for service. The carburetors were inspected several times after each start-up with no favorable response to any adjustments done to the needle height or float levels. There was an odd situation where the left side carburetor fuel levels were greater than the right side, despite careful float adjustments. The petcock was checked as it was dripping, even in the OFF position.

The petcock had been installed without a sealing washer for the attachment screw that holds the petcock to the bottom of the tank. Additionally, the back side of the fuel lever was uneven allowing fuel to pass the barriers of the 4-hole petcock gasket. Once the fuel lever was flattened out and a sealing washer installed, the petcock functioned normally. Both fuel lines were matched in length to alleviate any issues with fuel flow to each carburetor.

Having removed, cleaned and inspected the OEM carburetors three or four times, I had to start looking at other associated problems that might have been overlooked or assembled in error. Starting with the basics, the compression readings were about 140 psi, which is a bit lower than Honda’s spec for a normal engine. Low compression readings, when both sides are the same, can be indications of incorrect cam timing. This engine had new rings, which were not seated yet, so some leakage was to be expected. A leak-down test showed nothing abnormal, apart from some air leaking into the crankcase past the new rings.

All indications were that the cam timing was correct, although Honda’s tune up book showed the intake valve opening at 10 degrees before top dead center, and actual valve opening appeared to be starting at about 20 degrees. This might look like the cam timing was incorrectly set, however most cam timing readings are taken at .040” so with that in mind the cam timing was correct. I actually removed the top cylinder head cover to verify that the marks were correct, which they were. So, take that off the list of possibilities.

I observed that the aftermarket replacement ignition points were contacting at the very edge of the contact faces, rather than in a more central location. A bit of bending of the stationary contact brought the contact back towards the middle. The gap was rechecked and timing adjusted to suit. The spark advance was checked for proper function in advance and full retard positions. The ignition coil was an aftermarket replacement with the original spark plug caps installed. The caps were measuring about 10k ohms, instead of the preferred 5k ohms, so were replaced. So far, no “smoking gun” was found to cause the rich running of what appeared to be stock OEM or replacement parts.

A set of aftermarket, Chinese-made carburetors had been brought down originally, so in desperation, they were installed. These replacement parts had their own issues. The “set” was actually two right-side carburetor bodies, so that both had the carb adjustment screws on the right side and fuel feed fittings on the left side. Both carbs had the same slides with the same cutaways, as that is what a right-side carburetor would be equipped with.

The carburetors were fitted to the stock intake manifolds which had been flattened off with my little belt sander to ensure flat contact surfaces. Once fitted, the bike was started up and immediately ran cleaner and idled down comfortably without the rich running that was occurring with the “stock” carburetors. At this point I was truly baffled about why the stock carbs failed to function properly, and a set of Chinese carburetors, which had no markings on any of the jets, were working normally.

However, the Chinese carburetors had a different issue. The next day, the bike was hard starting and only ran on almost full choke. As it warmed up, I slowly lowered the choke lever until it would start to stall out again, which indicated that the needles needed to be raised up a bit. The right side needle was a 5 notch type with the clip all the way at the top.. so super lean. I moved the clip to the middle groove. The left side needle came out and was a completely different type with only 3 notches! I went for the full rich option and restarted the engine again. Like magic, the bike took throttle, off idle, and was smooth and responsive in a 5-minute test ride.

I reported this limited success to the owner of the bike project, but could not give a cause for what had happened… until I went to put the old carbs into a box for storage.

Looking carefully at the carb needles, I finally realized that they were of different material. One was a brass D2 Keyster needle, but the other silver-colored needle was not marked at all. Comparing the two, the profiles of the needle tapers were different, as measured with a caliper. Ah, ha! Maybe I was on to something important, after all. Then, I flipped over both of the carb slides, which appeared to be the same, as far as the material and coating was concerned, but then was shocked to see that one slide was an OEM Honda part and the other one was not marked at all! Sitting them side-by-side, I could see that the slide cutaways were a bit different and then looking even more closely, the whole slide bottom, where the needles are located were at a different height! The aftermarket slide was a completely different part, as far as dimensions go for the needle and the cutaway. Eureka, I found it!

I was able to track down a set of OEM needles from an eBay seller, then went to cmsnl.com for the other needle, plus a new OEM slide, plus a pair of OEM idle jets. I now have confidence that with the correct OEM parts installed, the stock OEM carburetors should work normally, as designed. It’s been an arduous task with many hours of removing, inspecting, cleaning and installing the stock carbs over and over again, expecting a better result. I think that has been described as “insanity,” isn’t it?

I thought that this was the end of the story, however the bike had other ideas. When the fueling issue seemed to be solved, a long downhill run, a part of my testing process ended when the bike slowed down for a corner and then went completely DEAD! It had blown a 20 amp fuse. I had no other fuses with the bike and I was stuck a mile away on an uphill return. I called a couple of neighbors and neighbor Paul picked up the phone during his grocery shopping and said he would come and pick me up shortly.

I pushed the bike up an angled cement corner, made for wheelchair access, and left it under the shade of a palm tree. Paul came by, picked me up and dropped me at home. I loaded up the Tacoma and headed back down the hill to where the bike awaited my return. Loading a 280 lb. bike, even with my long ramp into the Tacoma can be challenging, but when I arrived at the bike a somewhat scruffy man was sitting next to it, accompanied by his dog. We spoke about the bike and what had happened. I could tell that he was looking for signs that this was my bike and I was the rightful recipient of it. He happily helped me load the bike into the bed of the Tacoma and walked back to his waiting Honda Accord, with the dog in tow. How amazing that someone came out of nowhere to help out just when I needed it the most!

I unloaded the bike and set to work finding the cause of the short. The bike only has one fuse, so when it is blown you are completely inoperable. I have a resetable relay connected to a set of wires with clips on the end. You can put them on the ends of the fuse holder and it will click on and off, when a short is present. Of course, it seemed perfectly fine all of a sudden. I did track down some worn wire for the rear brake light, which was repaired. Also, the fuse, in the fuse holder, should have been a short 15A fuse, but was a longer 20A fuse. The length of the fuse, caused the ends of the wires that attach to the fuse holder to extend out beyond the plastic fuse holder. That made them vulnerable to contacting a grounded frame area and create a dead short. I put a shorter fuse in the holder and pushed the wire ends into the plastic holder out of harm’s way. Nothing else was evident, so I turned my attention back to the carburetors.

On the next short run, partially down the hill, the bike ran well for about a minute, then went off on one cylinder. I slipped the clutch and revved the engine sky-high to try to get it back home again, just a quarter mile away. After it sat for a moment, it suddenly caught on again and I nursed it back home again. The problem was that the right side carburetor was running out of fuel, while the left side was doing fine. I rechecked the float level with the carb still installed and looked for any signs that perhaps the float was somehow contacting something inside and shutting off the fuel flow. I did another around-the-block test and it started to run on one cylinder again. No matter what I did, it wouldn’t keep fuel in the right carb bowl.

I had already bought another aftermarket petcock, in case there were problems related to the one that came with the bike. I drained the tank and removed the petcock. On more careful inspection I noticed that the two holes that feed the fuel lines to the carburetors were not on the same level. Wow! Could this be a factor in the fuel feed issue? The new petcock had a little screen on the reserve port whereas the original did not. Grasping at straws, I installed the petcock and hooked everything back up. Again, the fuel wouldn’t flow into the carb unless the bowl was dropped down and the float allowed to open the float valve.  The replacement petcock had its own problems. The space where the attachment screw is narrowed more than stock so the proper screw gasket (not included with the petcock) doesn't fit! I had to slowly grind down the OD of the gasket so it would fit snugly down and seal the screw head.

A friend suggested that I try another float bowl. The OEM carb bowls fit right up to the Chinese copies, but the result was the same. I removed the air filter and the carb from the studs to have another look at the bowl venting system and rechecked the float level with the carb held on the side, with just the weight of the plastic floats touching the needle. The measurement was different in that angle, so was re-adjusted again to 21mm.

Comparing the float bowls, I noticed that the brass overflow tube on the aftermarket carburetor had a really tiny hole. The carb had flooded over previously, so I knew that the passage was opened. But when I compared the OEM bowl to the A/M version, the original brass tube had about a 1.5mm hole vs about half of that on the copy. I opened the tip of the tube up with my 1.5mm drill bit and put it all back together once again. I turned on the petcock, waited a minute and then shut it off and removed the float bowl. It was FULL! 

I re-installed the air filter and side cover and went for a short ride just to test the performance. It was greatly improved and only hinted at a big of richness just off-idle. I removed the mismatched aftermarket needles… yes they were not a match on the same set of carbs, too! I compared all needles from both carbs and discovered that the D3 needle was match for the other brass needle and the two silver needles were also about the same. I dropped the needles down to the #2 groove and reinstalled them again. Suddenly, the bike felt and sounded like a almost normal CL175 Honda twin again. I brought my fuse tester with me, just in case, but made the full downhill test run back to the place where the fuse had blown before and then turned back around for the return leg. It was running well; as well as it could on aftermarket carbs and a mix of non-OEM carb bits.

Bill M. was on his way down to pick up the CL175 and leave me an XR75, plus the chassis for the SL100 engine that I had finished rebuilding. Obviously, I was very pleased to have finally conquered the worst of the bike’s problems and felt it was safe to drive regularly. I would feel even better once the OEM carb parts arrived from Holland. At some point the original carbs can be returned to the engine, for which they were intended.

I lost track of the actual hours of work devoted to analyzing and developing some strategies for a successful outcome. In the end there is a sense satisfaction that perhaps I learned something new, when facing similar challenges in the future.

Well, it certainly had me going round and round, unfortunately overlooking what was obvious in hindsight. It’s difficult enough to repair these old bikes given the lack of original parts, here in the 21^st Century. While the aftermarket vendors try to supply the needs of owners, unfortunately, the lack of quality control and design detail can cause a world of frustration, in cases such as this.

In situations, such as this, when nothing makes sense, even though you think that everything has been done correctly, you have to backtrack and dig deep into the minutiae of the smallest details. A small discrepancy can derail your best efforts to troubleshoot and diagnose the problem. In the end, you will find success.

Bill Silver

aka MrHonda

www.vintagehonda.com

08/2024

CL175K3 Blue tape special

A few months ago, my friend Bill M. contacted me about “rebuilding” a CL175K3 engine for a project that he was doing for one of his friends. The plan was for him to bring me the engine to rebuild and he would be restoring the chasssis then bringing that down here for the engine installation and then put all the bits and pieces back together again. The bike was purchased as a partially started project from a previous owner and the whole bike was disassembled.

The engine arrived with the lower end in a screwed-together wooden box, while the top end and carburetors were in separate bins. After about 15 minutes of undoing all of the wood screws, the bottom was revealed to have a damaged kickstarter shaft. A new one was provided, so this was obviously going to be a full teardown and repair. The engine was otherwise in decent condition internally, but required cylinder honing, valve seat repairs, vapor blasting and installation of the fresh parts. It was still on STD bore and the pistons were reused along with new rings.

Whoever started the project, was apparently new to the hobby, so virtually each and every single part was labeled with blue masking tape, including all of the wire connectors. So, part of the process was to peel off all of the blue tape from the components and clean the parts of  the remaining adhesive.

The engine rebuild was mostly uneventful, apart from having to run around town, hauling the parts back and forth to my friend with the vapor blasting machine. A set of aftermarket carbs were brought along with the engine parts, but the originals seemed to be worthy of a good cleaning and kit installation.

Once the engine was completed, it sat for a couple of months while I was doing several other projects and waiting for Bill M. to finish the chassis and find time to marry the two project halves together. Finally, in Aug, fully four months later, the the chassis was delivered on an early morning trip from OC and work began. The engine was shoehorned into the frame and all of the engine bolts fed into their respective places. Bill had brought down a copy of the parts manual, so we could refresh ourselves about what went where and what might be missing. Slowly, on a very hot day, the bike began to take shape, rising like a Phoenix from the pile of parts emerging from their blue-taped packages.

The CL175K3 model is the only one that had a high-mounted front fender, which was composed of several various adapters to fit the bottom of the fork stem. According to some parts lists, the K3 was sold in 1969-70. The wiring harness was fed back into the frame recesses at the back of the chassis and the ignition switch mounted up on the forward bracket, beneath the gas tank on the left side. A charged lead-acid battery was pulled from its box and dropped into the battery box. These batteries have a vent tube that needs to be routed carefully, to prevent acid damage to the chassis during operation. I situated the battery so the vent was towards the rear of the battery box.

At first only the neutral light came on when the ignition switch was switched to the ON position. The bike had been supplied with a little aftermarket cube bridge rectifier in place of the OEM selenium unit which mounts on the inside of the frame behind the carburetors. When I touched the battery ground lead to the battery there was a strong arc, indicating some kind of short circuit. The only thing that is active when the key is OFF is the rectifier, so I assumed that it had a defect and we ordered a $100 OEM unit from an eBay seller.

In the meantime I was puzzling over the other electrical system issues, starting with the tail light function. Whenever a bike chassis is powdercoated or even painted, all of the ground paths need to be established again, as the powdercoat becomes an insulator to electrical circuit pathways. I had cleaned off the usual places for proper grounding but when I checked the power to the tail light, it showed power to and through the bulb, but my test light lit up only when it was grounded back to the battery. Studying a copy of the online wiring diagram didn’t show any separate ground path to the harness wires, except though the various components, but they were still mostly isolated from a good ground path. I finally eyed a single green female ground connector by the battery with no place to go. I made up a jumper wire and connected it to the female connector and grounded the other end where the turnsignal flasher mount bolts to the frame. Success! All the lights came on and power seemed to be restored to all of the lighting and other functions.

A few days later, the spendy orange rectifier arrived and was installed after removing the left side carburetor again. The mounting stud was well grounded and I was looking forward to completing the electrical system. But, as soon as I touched the two harness connectors together, there was a big flash and wires started getting melted! I quickly pulled the two connectors apart and reviewed the wire colors for each side. The harness side connector had the red hot wire across from the green ground wire, but these colors were swapped on the rectifier side. Obviously this was a dead short to ground for the battery feed line. I pushed the wire connectors out of the harness side to match the rectifier colors and plugged them back together again, gently. There was still some arcing going on, but less than before.

Finally, I thought to check the battery connections and finally noticed that the battery was installed BACKWARDS! This was the cause of all of the electrical arcing from the rectifiers, both the aftermarket one and the OEM version. MrHonda had a senior moment and hadn’t paid attention to the battery polarity. The battery was installed with the markings turned away from me and I was using the position of the battery vent tube as the indicator of the orientation of the battery when mounted in the frame. It all became clear in an instant and now the damaged rectifier needed to be removed and replaced again. In looking at the rectifier, only the green ground wire that comes from the connector to the side of the rectifier mount was fried, so the rectifier through bolt was carefully removed, and a new wire with a ring terminal was installed. With everything re-attached, there was no arcing when the battery was re-connected and all of the rest of the electrical functions were operating normally.

In order for the Scrambler exhaust system to be installed, the left side air filter must be attached to the carb and then the left side cover snapped into place. Then, the wiggly Scrambler exhaust pipes can be hooked back into the exhaust ports and attached at the rear mount. That done, the bike was rolled off the work table and down to the driveway where the fuel tank was waiting to be installed.

The petcock appeared to be an aftermarket piece, already connected to fresh hoses and inline filters. The petcock mounting bolt was missing the sealing washer, so I had to dig up one from my pile of leftover carburetor parts. Then the screw wouldn’t go into the tank without chasing the threads with a 6mmtap. Once everything was put together, some fuel was poured into the tank and the moment of excitement arrives. The original kickstarter which had flattened out splines was replaced with an aftermarket piece which was an inch shorter than the OEM unit. This made kickstarting a bit of a chore as it was near the rear footpeg. I had already checked the ignition timing, so it should have fired up quickly. After a dozen kicks it coughed to life reluctantly, then stalled out. I looked down to see gasoline dripping down from the left side of the engine and oil dripping down on the right side of the engine. Now what!!!!!?!?!??!

The left side carburetor was dripping from the overflow tube and even with the petcock turned to the OFF position, there was still a persistent leak. The right side leak was from the oil filter cover, which had been sealed up with new o-rings, but continued to leak after several inspections and measuring the o-rings for the proper sizes. I happened to have a spare outer o-ring so stacked two on that side and the oil leak ceased. I tried to access the left side carburetor float bowl to see if something was obviously evident, perhaps with a failing float from a pinhole. It always seems that if you are working on a Scrambler of any size the left side carburetor is the one that will have an issue.

The exhaust port gaskets were supplied from an ancient gasket kit and consisted of some asbestos wrapped with copper wire. These compress down to nothing when installed, and the result was exhaust leaks at the flanges. The pipe packing that seals the two exhaust pipes together at the rear junction was mostly gone, so there as a leak back there, as well. So, the tank came back off so the petcock could be rechecked for the dripping issue and the exhaust removed again for new seals. With the exhaust removed the carburetors could be reinspected again. The left side drips had stopped, but when the engine was running briefly, it sounded like it was running rich on the right side, which was confirmed by a black plug when removed for a compression check,

New parts were ordered and the bike’s carburetors removed and checked again. There were aftermarket kit parts installed and they are often not to OEM specifications.

In the meantime, more electrical work was required to reconnect all of the wires inside the headlight shell. The rubberized instrument lights that pushed up inside holes in the back of the speedometer and tachometer were mostly all toast. A previous person had wrapped a lot of black electrical tape around the bulb sockets in an attempt to keep them situated in the lighting holes, but obviously, this was a failed attempt. I happened to have a string of instrument light wiring from a different model, but all of the socket rubbers were in great shape. I snipped here and there, finally getting them all spliced in for functioning instrument lighting. I had to special order the 12v 3w light bulbs to fill all the empty holes.

When I went to fit the headlight assembly back on, the left-right adjustment screw and bracket were broken away from the back of the reflector. When the rim was test-fitted to the headlight shell, it became obvious that the shell, which is metal, was out of round and painted that way along with the other metal parts (plastic side covers) on the bike.

I had some various woodworking clamps hanging in the shop and one was big enough to reach around the perimeter of the shell and with some strong twists of the clamp, brought the shell back to a circle once again, without damaging the painted surface. The left side headlight bracket had a bend in it, which needed straightening. The bike had surely been crashed at some point and the damage was left unattended by the painter and previous owner. Finally, all the lights started to function, but the headlight assembly isn’t centered with the midline of the front wheel, so more work needs to be done there.

The bike was run on and off my work table, to the driveway near the garage door opening for follow-up work on the fuel system. Repeated removal, inspection, cleaning, adjusting and re-installing of the carburetors failed to remedy the fuel fouling of the spark plugs. A more detailed examination of the associated components in the ignition and fuel systems didn’t give a solid clue as to the cause of the carburetor problem. It was finally resolved when a comparison of the needles, slides and idle jets revealed that the aftermarket parts were not a perfect match to the OEM parts.

See the next story on CL175 troubleshooting for how the process was performed and how it was finally resolved after hours of trial and error, including the replacement of the stock carbs with some Chinese copies. 2024 has brought in very difficult project bikes to sort out and rebuild to specs. It ain’t easy being MrHonda sometimes.

Bill Silver

www.vintagehonda.com

8/2024

Another day, another Scrambler….

Well, they just won’t stop coming. Latest bike is an early 1964 CL72, painted orange, supposedly from the selling dealer with some 1963 features, like a sand-cast front hub and even the oil pump. It was in overall nice condition, but the owner complained about the transmission shifting erratically and the engine had been freed up after weeks of soaking and heat until it finally freed up. He was able to get it started and running, but the engine rpms were uneven and the head gasket was leaking. He had also swapped out the clutch fiber plates with Barnett performance parts, but kept the original springs.

After drop-off and initial evaluation, I dove into removing the 100lb lump and began tearing it down for inspection and a full overhaul. I had to drill the heads off of three of four cylinder head side cover screws to start with. Once the top cylinder head cover was removed, the camshaft lobes looked a bit rusty around the edges. Apparently, the bike was either mostly original or rebuilt and then left sitting for something like 20 years. The camchain tensioner was removed at the back and the roller was seized up solid. Somehow the long-term storage had created some moisture inside the tensioner roller pin and bearing, locking it up.

Pulling the cylinder head off, yielded some surprises. Usually, when “stuck” engines are freed up, the result is the rings have been stuck in the piston ring lands, causing a loss of compression. The owner initially tried to do a compression check with a push-in gauge and found 90 on the left and 140 on the right side. Before he left, we used my screw-in compression gauge and got 175-180 readings on both sides! The tops of the pistons had a little layer of black carbon from oil burning and perhaps carb metering problems. When the cylinders were raised, the rings were all free in the pistons and the pistons were all STD size. The edges of the rings were really sharp, having scrubbed all the corrosion off the cylinder walls that had kept the pistons stuck in the bores. Removing the top compression ring and putting it in the bottom of the cylinder bore gave me a .032” gap, which should have been about .006-008” normally.

I used a ball-hone to scrub the cylinder walls, to determine how much corrosion damage had occurred but the bores looked surprisingly clean. There was a bit of a corrosion ridge/ring just where the top ring lands, but I was seriously considering just buying new rings and re-using the pistons again with the cleaned up bores. Finding machine shops here in San Diego, has become increasingly difficult as the guys who have been in the business for many years are aging out and suffering from various ailments.

Calling my friend Tim McDowell in MD, to order some gaskets, seals and a screw kit, lead the conversation to mention that he had a whole set of cylinders, bored to. .50 oversize with pistons, rings, clips all ready to go! We made a deal on the whole package and it was shipped out quickly.

In the meantime, the bottom end was dismantled including the revised clutch parts. Nothing much was amiss but the oil filter was somewhat tight on the shaft. Once the cases were cleaned off of all the clutch and shifter hardware, they were separated for the inspection of the transmission gear dog overlap. As suspected, the 2^nd gear dogs were a bit rounded off where they were clashing against the adjacent gears and the overlap was minimal. This is not unexpected given the early production of the engine, as most are similarly found to be lacking in overlap.

As a bonus, the owner brought down two big plastic bins full of “extra” parts, including a couple of transmissions. I sifted through the transmission sets and found a nice 2^nd gear, plus a NOS shift drum! The transmission gear cotters were removed so I could do the X swap in the gear ratios and the cotters that came out were offset ones! So, after some mix-matching of gears and cotters, the transmission should be in the best possible condition. I did replace the low gear bushing with one of the new reproduction pieces and the kickstarter pawl which was wobbling in the end of the shaft. The end bushing had some usual wear from the pawl rubbing up against it, so I decided to try to find a thin thrust washer to make a better surface for the kickstarter pawl to push up against. I found what seems to be a possible candidate with a Kawasaki washer that was ordered online.

The engine cases, cylinder head and associated covers were taken to a local engine rebuild shop for de-greasing. There was a lot of black goo inside the engine surfaces, partly from the camchain rubbing up against the seized roller when the engine was running. There was the usual gunk that covers the bottom of the cases, due to the use of original non-detergent oils, which were recommended by Honda in the early days.

The head was stripped of the cams, rockers and camsprocket before cleaning. The camsprocket weight springs were really loose so the ignition timing was all over the place when it was first started back up. The sprocket was sent to Tim Miller, in TX who specializes in building racing 250-305 engines and has come up with an effective rebuild for the sprockets, which lessens the total advance. This allows for the idle timing to be at 10 degrees BTDC instead of the usual 5 degrees, which Honda used. The added 5 degrees makes for a happier engine idle overall. New valves were ordered from DavidSilverSpares and the head was taken back to the machine shop for seat grinding to ensure full compression.

Little roadblocks…

Well, the nice NOS cylinders from Tim McDowell, which came with .50 MC pistons, turned out to still be on STD bore sizes, so with a fresh set of STD rings, I can reuse the OEM pistons and solve that problem. HOWEVER.. the NOS cylinders was a late-model die-cast unit, which uses the narrow 32mm tensioner that I didn’t have in stock, I had ordered the Capellini tensioner sprocket kit for use on the wide tensioner that came off of the stock cylinders. So, now I have to scrounge around for a usable narrow tensioner body and remove the old roller or Option 2 which is a NOS tensioner on eBay, but the tensioner doesn’t come with the spring and bar to push the roller out against the camchain. These parts are specific to the -020 tensioner assembly. Just when you think you have your ducks in a row……

Well, I did both.. bought the new tensioner and then discovered that I had a used one in the engine parts box after all. Problem solved.. or not?

The rebuilt cam sprocket came in and was carefully installed on the endless camchain. It’s a tricky proposition and required clamping the top end down with some sockets and nuts so I could join the two camshafts into the master spline of the sprocket. Once that was accomplished, it was time to install the camchain tensioner… and it wouldn’t fit into the back of the cylinders. Perhaps the Capellini parts are slightly wider than the originals, but it appeared that there was some casting flashing in and around the tensioner hole that was jamming the tensioner arm roller hardware. I tucked some shop towels into the opening and then carefully ground out the insides of the cylinder opening. It helped but still needed a bit of a push to clear the opening and finally fully install.

The cams and top-end bearings were all lubed up and the top cylinder head cover was installed. The top nuts were torqued down and only the oil pump installation is left after the engine is flipped over to expose the bottom end.

It takes over an hour to either remove or reinstall the engine assembly, given all the little bits to round back up and re-attach. I used a remote fuel bottle to connect to the carbs and with a half-dozen kicks the engine fired up and sounded pretty healthy. I had set the ignition timing statically just to get it running, but the project stalled until the requested Pro-Trigger electronic ignition system arrived from Florida. In the meantime, I noticed that when I rolled the bike around the massive 4.00x19 rear tire was making flat tire sounds. The tire is so large and so old that there are no date codes marked on the sidewalls. Checking air pressure, none was found. I aired-up the tire to 30 psi and shortly thereafter it went back to zero. I called my local shop to check on inner tube availability and thankfully they had one in stock. I removed the wheel assembly and hauled it down the eight miles to National City Motorcycles, where the owner, Rob, put it on his tire machine and replaced the tube and rim band.

After a few days, the ignition system arrived and was installed. It’s a bit fiddly because the trigger wheel with the magnets is just a round section of aluminum with no indexing to setup the correct timing. It’s a bit of trial and error, but eventually, the timing came in correctly and the bike was fired up once again. Winding down the final adjustments, the tank and seat were re-installed and the first test ride done, just around the block. Because the crossover tube fittings had been blocked off by the owner to reduce the fuel spilling when the tank was removed, the fuel supply to the petcock is somewhat limited to the right side of the tank. There seemed to be sufficient fuel in the tank, so a longer test ride was undertaken. The usual route is about a mile, down a long hill to a turnaround at the bottom.

I could feel it dropping a cylinder as I reached the bottom and finally it quit altogether. Rechecking the fuel supply on the petcock side and turning the petcock lever back and forth between On and Reserve, got it fired up again, but it only went about a quarter mile back up the hill before it quit again. I pulled the fuel lines off to the carburetor and nothing was coming out in reserve, but fuel did flow in the On position. The bike fired up again and I made it back home, avoiding the drama of calling a neighbor to come and fetch me, then returning with my truck and having to load up the bike for the ½ mile trek back to the house.

The bike was fitted with the yellow MotoBatt battery, which are generally very reliable. I noticed some corrosion build up on the terminals, which I hadn’t seen before on any of these batteries. Finally, I decided to check the voltage with a meter and the news was grim. 10V with the key off and 9v and dropping with the key On and the headlights On. When the bike was fired up again, the voltage continued it’s decline… the charging system was not working. I gingerly fished out the rectifier which was one of the later solid-state units, instead of the orange selenium units normally found on early bikes, but the test results were zero. It was a dead soldier.

I fished around and found one of the little cube full wave bridge rectifiers, that Radio Shack used to sell and with some connectors and extra wire, the unit was installed in place of the old rectifier. I had put the battery on the charger for an hour or so, which indicated 12+ volts at rest, so reinstalled it and started the bike up again. The voltmeter jumped up towards 13v, even at low speeds, so the electronic ignition was getting a full dose of juice as were the ignition coils. One more problem solved, but one more to go. Even after the battery was charged, the battery voltage dropped from 12 to 10 with the key On, so a new replacement was ordered.

I removed the gas tank and laid it on the left side so the fuel went to one side which allowed for removal of the petcock inspection. I was surprised to find that there was no brass tube fitted to allow for a normal ON fuel feed, before requiring the Reserve to finish draining the tank. Then, as I continued to inspect the petcock body, I realized that there was no reserve port function in the petcock body. If I had installed a brass tube into the petcock body, there would be fuel leftover as the level dropped and no way to finish using up the remaining fuel. This explained why there was no fuel flow in Reserve position as there is no way for fuel to exit the petcock. I removed the petcock body and probed the little fuel feed ports, finding some leftover debris and scale in the On port. So, with the understanding of what had been happening with the petcock and low voltage, I was getting more confident that the bike was okay, overall. However, the shifting issues were particularly troubling during the test rides. The petcock continues to perplex me, as I have never seen that before on a stock Honda petcock.

I had replaced the low gear bushing and re-shuffled the clutch pack to allow for clutch plate retention which was not possible before with the replacement clutch pack installed by the owner. I installed some of the offset cotters to help engage the gears, but had used some of the rare deep offset cotters, which were giving almost 90% gear dog engagement. In reflection, you can do too much of a good thing and the deep engagement may have been causing the gears to remain engaged rather than releasing easily when the next gear selection was chosen. Mulling it over in my head, the only sensible solution was to remove the engine once again, split the cases and re-do the transmission cotters. So, out it came again…

In the tear-down, I revisited the clutch plate stack and decided to replace the center hub with the later 5-plate version, which uses a thick Plate A and just one set of plates after that, using the retainer wires. This allowed the clutch plate set to more easily spin free at idle. Clutch drag at idle is a big cause of shifting problems, especially when finding neutral at a stop. These transmissions were designed in the late 1950s, so they can get caught up between gears, at times, if the shift selection isn’t done with some authority.

I replaced the .040” offset cotters with a set of the .020” versions, which reduced the gear dog overlap back towards 50-60%. There was some end play in the countershaft that causes the kickstarter pawl to get a bit cocked as the shaft moves in and out. I had ordered a 1mm thick thrust washer online that was a Kawasaki part and was able to insert it into the shaft next to the end bushing, which took up all of the end play without jamming the shaft up between the bearings. I sealed up the crankcases once again and reassembled the primary side with the updated clutch parts.

It was another hour of installation time ( 5 hours overall to R&R the engine and make repairs), but I was feeling more confident that the major problems were being addressed. Unfortunately, the right side carburetor started to drip from the overflow tube. The float was slowly sinking due to a pin hole so that was replaced. The drip continued once again and the float valve needle was replaced, finally stopping that leak issue. One final check of the spark plug caps turned up the left side with 17k ohms instead of the preferred 5k ohms. So, with that replaced, the bike started running better and better. 

As you can imagine, lots and lots of labor time is involved in doing the basic overhaul work, then sorting out all the associated problems discovered in the repair process in these 60-year-old machines. People who work on these bikes begin to appreciate how many problems arise and the amount of time and effort it takes to make them return to their former glory.

Bill Silver

aka MrHonda

8/2024

Wrangling a Dream back into shape again…

My friend, Don, who continues to feed me interesting and usually challenging vintage Honda projects, came by with a red 1966 CA77, which needed some help. He sent a video of it running, but it didn’t sound as crisp as usual.

The first challenge was that the original ignition switch was missing. Either it was cherry-picked for another bike or what seems to be the most likely scenario is that the bike got into some kind of accident or incident that damaged the switch. The headlight shell was damaged adjacent to the switch location from some kind of odd impact. The headlight rim was damaged where the bottom mount loop was broken off, so the headlight was duct-taped onto the shell for the moment.

The battery side cover was missing and there was an interesting fabricated battery mount with a metal strip that had ground terminal wires all attached from various parts of the harness. Speaking of the harness, the wiring harness was an aftermarket copy which has sometimes non-matching wire colors.

When the headlight was removed, all the bulbs on the bike were LEDs, instead of regular bulbs. The back of the headlight bulb reflector had been cutaway and an adapter for the LED bulb was JB welded into the rest of the unit. Even the high beam indicator and instrument light bulbs were LEDs.

I put out a call to the various Facebook forums seeking a headlight shell, headlight rim, battery cover and other misc parts. Fortunately, my local friend, Clark, responded and said that he had some leftover Dream parts from a bike that he owned many years before. I drove over to his house and he presented me with a box of nice bits, including a NOS headlight rim, a headlight shell that had been bead blasted and left to rust a bit. On top of that he had a rebuilt Dream speedometer and even a brand new Dream tool kit! We made a good deal and off I went to start working on the project again.

The headlight shell was solid but pitted from sitting un-finished after the paint was stripped off years ago. I bought some heavy-duty primer and some expensive Cardinal Red paint that is a match for Scarlet Red Honda paint and went to work. After a few coats of primer, I ran a coat of the red finish paint over the part, leaving it looking decent but not factory looking paintwork. It kind of matched the rest of the patina and what previous rattle-can paint that was done on various parts of the bike.

With the headlight shell ready to install, I snaked the four retainer bolts in from the back side and anchored the shell firmly to the front fork. Next was the used replacement OEM ignition switch that I had directed Don to buy from an eBay seller. From that point it was the task of sorting out the myriad of wires that had been spliced and twisted together.

In the meantime, I pondered the headlight bulb situation, as the LED didn’t seem like it was working. I had a leftover 35/35watt H4 bulb that fit right into the socket, but had rear facing connector tabs. The push-on plug that I had available made the whole unit too deep so that it would hit the speedometer cable when installed. I turned out the connector tabs ninety degrees and once the connectors were pinched into place, I coated them with GOOP and let it dry overnight.

In the meantime the parts search request came up with another headlight assembly from my friend Mike who has a lovely 1960 Dream. He had replaced the headlight with a NOS unit and made this one available to me. It was an early version that had the extra parking light installed at the bottom of the reflector. The rim was perfect, so the headlight was disassembled and the rim transferred onto the modified bulb reflector.

I charged the lead-acid battery but it didn’t have enough reserve to turn the engine over, so a new Motobatt battery was ordered up.

The othe big issue was that the carburetor bolted to the back of the head was some kind of Chinese-made Mikuni copy. While it did fit on the engine and into the air funnel, it had an enrichener lever instead of the choke lever and it was not accessible when the carburetor covers were installed. So, the word went out looking for an OEM carburetor, which are difficult to find now. I did discover a complete one that looked good on eBay for $150 so I went with that one. It came quickly and in good shape, although the air screw didn’t fit down into the carb body threads all the way. I found a good used air screw that fit better, so the rest of it went back together and installed okay. Fitting the carb and air tube to the OEM air filter is always difficult, but it all finally came together after a lot of squeezing of the tube.

The carb had a Keyster kit needle, so the performance of it was in doubt. Fortunately, it still had a #120 main jet, instead of the #130 jet that Keyster keeps putting into their kits for unknown reasons. With the carb mounted up and fuel feeding it from an aftermarket petcock conversion, I tried the kickstarter a few times and the bike sprang into life. The bike’s electrics were upgraded with a Charlie’s Place ignition and Dyna coil. The regulator/rectifier unit replaced the original rectifier, so a lot of upgrades had been done to the bike.

The idle seemed erratic, so when I checked it with the timing light, the spark timing was about 20 degrees advanced and I was getting a double strobe signal from the ignition. When I have seen this in the past, the camsprocket rivets had loosened up on a different bike, giving an erratic timing signal, but my experience with Dream ignitions is that the double-ended point cam had accuracy issues so that the timing was correct on one lobe and different on the opposite end. Considering that the electronic ignition would over-ride that condition, either the magnets on the trigger wheel were not placed properly or the camsprocket was working loose. When the camsprockets loosen up, there is a lot of ratcheting sounds that weren’t really present in this bike. I retarded the spark timing back to where there was a more accurate location and the engine settled down.

So, things were looking good so far, until I took it out for a test ride. When I pulled the clutch lever in and selected low gear, the bike jumped, stalled and stopped. I restarted it, rolled it down the driveway and then put it in gear. Holding the clutch lever in all the time, I drove it around the block, even shifting it into second gear, but the clutch was having none of it. Locked up solid.

I leaned the bike up against the garage wall to lessen the oil loss when the clutch cover was removed. Whoever had installed it many years ago, had gotten the shift shaft seal cocked on the installation and turned the edges of the seal inside out, causing an oil weep. The clutch assembly was a mass of rust and corrosion that required forcing the plates out, one at a time from the clutch hub and outer basket. Small wonder that it wouldn’t release! I sifted through my leftover clutch bits and was able to assemble something that was close to the correct configuration with a new seal.

The problem/challenge with 250-305 Honda clutch assemblies is that there are several different thicknesses of both the steel and fiber plates leading to a list of parts options, depending upon whether the clutch is a 4 plate, 5 plate, 6 plate setup and that varies whether the clutch is for a Dream or a CB/CL model. There are several different clutch hubs, machined with grooves for the clutch retainer wires, but the grooves are in different locations, depending on the application. The clutch hubs always begin with a “Plate A” which is the anchor for the rest of the stack. Those, of course, are of different thicknesses, varying with the application. Whenever possible, use of the later 5 plate clutch used in the CB/CL models is the preferable configuration. The last generation pressure plate has angled holes to help spin out the trapped oil, which creates slippage problems. 

Given that the stack height of the clutch pack is the same for any and all applications, the only leftover variable is the clutch springs. Dreams use some lighter-weight springs, superseded to the 425 code parts, which are actually from a CB750, but less of them. Honda had problems with the added horsepower on the CB/Cls, so had a couple of spring options. The original CB72s had 268 code springs, with the CB77s using a 275 code spring, which was superseded by the 323 code parts from the CB500 Four. Curiously, Honda then recommended the 275-810 racing clutch springs to help with clutch slip, but the springs are so short and stiff that they appear to coil-bind at full compression and the lever pressure is excessive for street use. Honda used a 6-plate setup previous to the late 5-plate type which is most effective and gives reasonable lever pull feel.

So for a Dream, which has less torque and horsepower, a late 5 plate clutch setup with softer Dream springs would work fine for that application. For this bike, the leftover pile had a number of the all-fiber plates used on Dreams and early 6 plate CBs which were sufficient to create a working clutch assembly. The CB/CL 5 plate clutch discs are metal backed so easily recognizable

from the early all fiber plates. They are thicker, of course, because there are only 5 sets.

When the stack height is correct, the index mark on the clutch adjuster, located in the kickstarter cover will align with the mark on the cover. If you wind up too far off of the alignment marks, it means that the clutch stack height is incorrect and/or there is excessive wear on the clutch adjuster threads. The clutch adjusters are now NLA from Honda, however CMSNL.COM is recreating replacement parts, which are now in process.

With the clutch situation mended, all that was left was a non-functional front brake. I disassembled it at first, only to find someone had over packed the hub and speedo drive area with chassis grease which coated the brake shoes and brake drum. There didn’t seem to be excessive wear on the shoes, but after it was assembled again, the brake function was nil. I ordered a new set of shoes and a replacement brake cable. I used a flapper tool to scrub the brake drum liner and flushed it with brake cleaner. The new shoes, ordered from an eBay seller were actually OEM parts with Hm markings. Once assembled the brake began to have some effect when the lever was pulled, but now the new shoes would have to bed into the brake drum, so overall braking was still less than wonderful. Honda used rather tiny SLS brakes for the Dreams, which are not highly effective in daily use.

I had to juggle the battery box plates around to reduce the pinching effect on the Motobatt battery. The terminals are variable on the Motobatt, but everything finally connected properly and the engine starts up quickly with fresh battery juice. All that was left was the missing late model battery cover, which seemingly was now impossible to source from forums or online. Finally someone posted a black cover on eBay and that was snapped up to the tune of $150 and will still need to be painted.

The red Dream finally made its exit, several weeks after arrival, only to be replaced by another red Dream from my friend, Cat, who owned the bike since I built it in 1994. She had to sell it a few years ago to a friend in AZ, then was notified that her friend had passed away and had directed that the bike go back to her again. After a 1,000 mile round trip, the bike has returned, minus the original carburetor which went walkabout somewhere in the garage. The bike was retrieved and a replacement carburetor acquired. The bike will be here, briefly (hopefully) for new tires, carb clean and installation, a new battery and general tune-up. There is one more Dream in the queue, due for a tire change and other work, arriving in early August.

So, for the past month, the garage will have housed 2 red Dreams, 3 CB77s, 2 of which are mine and one was one I built in 2016, then bought back and resold 3 more times before coming back again for some needed repairs. Then, there is the 1963 CL72 whose engine is on the workbench for a full overhaul. They say that “Rust never sleeps” but neither does MrHonda, lately.

Bill Silver aka MrHonda

7/2024