As posted previously, I'm about to become the owner of one soon (just haven't found it yet). This will also be my first bike (very exciting). So I'm look forward to learning as much as I can about these as possible. I was hoping I could tap the cumulative experience of the community and hear what some of the common problems/issues are that have been known to affect these bikes.
I imagine there was a at least a few falls that have since been corrected through 40+ years of engineering. Just curious as to what some are so I can watch out for and expect what they would be.
Thanks again, Scott.
What are some of the common issues that afflict the CB77's?
Spargett, Welcome to our forum. This is actually a pretty broad question, it depends on each individuals experience. Having said that I believe that the transmission is the #1 trouble maker. When things get worn they tend to skip in and out of gear. The repairs are time consuming and fairly expensive. #2 would be the electric starter clutch. At least its easy to repair and parts arn't expensive. My overall thought is the CB77 is a well desinged and built bike but many have come to us now 40+ years old and have had a rough life. So anything can go wrong. Still, I'd hate to try to restore a brand X bike under the same conditions. Kustommusic
One of the common afflictions that I've found is oil leakage around the base of the spark plugs. Honda had sent out a service bulletin regarding this phenomenon back in the 1960's, and it has to do with the cast iron 'skull' separating from the aluminum castings of the cylinder head, thereby causing a seepage at the joint around the spark plug holes. Honda basically said it was no big deal, but did offer a fix for it. If I can track the service bulletin down, I'll post it.
One out of 55 had this!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!LM
All I know is that I'm one of the 55, and Spargett could be too (didn't know that was the exact ratio, so I apologize).
Here is the info: SL #65 6/1/66 HONDA MOTORCYCLE SERVICE BULLETINS OIL SEEPAGE NEAR SPARK PLUGS IN ENGINES WITH ALUMINUM CYLINDER HEADS American Honda receives occasional complaints of the tendency for certain models with aluminum cylinder heads to seep a small quantity of oil near the spark plugs. In some cases, dealers have replaced cylinder heads in an effort to eliminate this seepage. This bulletin is intended to clarify our policy in relation to this problem, and to suggest some countermeasures that we have found to be effective. In cases where it can be confirmed that the spark plug sealing washers are not leaking, accumulation of a stain, or oil residue, near the spark plugs can be traced to oil seepage from the joint between the combustion chamber "skull" and the aluminum cylinder head casting. Since the spark plugs are threaded into the iron skull, rather than into the soft aluminum casting, this joint must "come to the surface" near the spark plugs. Although it is no mystery how oil reaches the outside of the engine, it is difficult to determine the source of the oil. Apparently, oil reaches the joint from the oil-bearing chambers through internal porosity in the aluminum casting; such porosity is extremely difficult to avoid. Once oil enters the joint, it has an almost unimpeded leak path to the outside because the skull is not bonded to the head casting. Our studies have shown that machines experiencing this problem can be graded into three broad categories, based on the severity; each category should be dealt with in a different manner: 1. A stain or oily residue collects near the spark plugs over a period of several days or weeks. Seepage of this magnitude should be considered a normal, inescapable consequence of the cylinder head design, and no repair should be attempted. Customers complaining of such seepage should be assured that no defect exists; suggest more frequent cleaning of the engine. 2. More severe seepage causes definite accumulation of liquid near the plugs; following a hard run, oil droplets or streaks can be found on the air cleaner covers, etc. Although a "defect" is not necessarily indicated by this seepage, countermeasures are often necessary to satisfy customers. We have found that seepage can be slowed or stopped in the following manner: a) Remove spark plugs and completely clean the region around the plug holes so that the joint between the skull and the casting can be seen. b) Using a dull punch, punch a ring of depressions, tangent to each other, in the aluminum immediately outside of the joint. 3. Liquid oil "bubbles" from the skull/head casting joint, puffs of vapor can be seen when the engine is suddenly accelerated. In these cases, a definite defect is indicated, i.e., actual separation of the skull and head casting. In most cases, however, the cylinder, rather than the cylinder head , is the faulty part. We have found this problem to be most commonly related to "sinkage" of the cylinder sleeve in the cylinder casting, such that the upper surface of the cylinder sleeve is below the upper surface of the cylinder casting. When this "sinkage" occurs, the Honda 250-305 Super Hawk Restoration & Maintenance Guide combustion chamber skull is not forced into intimate contact with the cylinder head casting and severe oil or vapor leakage, near the sparkplugs can occur. The recommended repair is, of course, to locate and replace the faulty part. Source: SL #68 4/29/66 HONDA MOTORCYCLE SERVICE BULLETINS
55 is the number of heads I've personally worked on and 1 was a leaker. You don't show what HONDA did at one time suggest how (other than replace) to fix the problem of oil at that plug location. I did the HONDA fix and it didn't work even close. I'll mention that the points, rocker adjustment screws, cam chain tensioner, shift drum, shift rollers, kick starter shaft, second gear, early clutches, carb slides and I'm sure there other engine and bike parts which can be added but I don't need to copy any HONDA page to show what I've learned by being my own and for others mechanic who knows this due to greasy hands and clothes. ................lm
RIDE IT DON'T HIDE IT!
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