Hello and request for help.

[Al Urquhar]

Hello to all you Honda305 folk. Just by way of an introduction, I have been 'into' motorcycles (motorsickles?) for a long, long time as, sadly, I'm now well stricken in years. As well as my modern daily ride, I've also got a few old British clunkers which serve to remind me of my (possibly) misspent youth and, in January this year I decided to buy a CB77 to add to the stable.

Although I have owned several modern Hondas (CBR600, VFR750's, Pan European, Goldwing) I've never previously tried one of the early models and I became increasingly curious to see what I might have been missing. I have to say that I have been very impressed by the CB77, especially so when judged, as it should be, against its British contemporaries, of which the other old nails I own are reasonable examples.

My bike is in good, restored, condition but, unsurprisingly (it's 51 years old after all), needs one or two tweaks to bring it fully up to the mark. I do find the bike's well-documented reluctance to change into neutral at a standstill with the engine running to be difficult to live with (finding a neutral between third and top while I'm riding, however, is not difficult at all!) but, by carefully following Loud Mouse's detailed instructions on clutch-adjustment, I have managed to improve matters somewhat, but still no cigar.

Another shortcoming that I'm currently trying to resolve is a slight tendency for it to leak oil. With my British iron of course, oil leakage, of almost Exxon Valdez proportions, is all part of the 'charm' but, on a Honda? No, I don't think so. Oil seepage at the front of the engine I traced to a poor rubber seal on the left exhaust tappet cover and a need for the cylinder head bolts to be re-tightened (following previous top-end work, I imagine). Having dealt with those issues, I have noticed, on my last couple of rides that my left boot has collected a film of oil and post-ride inspection shows it to be coming from the tacho-drive cover. OK, thinks I, just whip it off, clean the mating surfaces, ensure the gasket and sealing rings are present and correct and the job's a good 'un. However, having disconnected the drive cable and removed the four cross-headed screws from the cover, I can't get the cover off. It will move about a quarter of an inch then appears to hook up on something and won't come any further. Rather than apply my usual approach of 'if it won't shift, you're not pulling hard enough' I thought I'd better check with you guys as, clearly, I don't really know what I'm doing here and neither the workshop manual nor the parts manual are much help as they don't show how the drive connects up behind the plate which, I guess, is what's stopping it from coming off.

Rather a long-winded intro (sorry about that) but I'd really appreciate your help on this one (and any views you may have on that elusive neutral, too.) Regards to all, Al.

[G-Man]

Al

That cover should come off with just a little persuasion. The tacho drive is just a wom gear on the camshaft driving a gear on the end of the cable shaft.

http://www.cmsnl.com/honda-cb77-general ... ml#results

The oil may be coming from there or you may have the other achilles heel of these bikes. That is oil getting between the cast steel 'skull' in the head and the parent alloy of the head.You can search the problem her or with Google. Honda did bulletins in the 60s but didn't really solve the problem.

Just for the record - my untouched 1966 350 Matchless doesn't leak any oil. And yes, it has got some in. These Hondas like any bike that's been apart a few times do have minor incontinence problems..... :-)

G

G

[Al Urquhar]

Many thanks for your quick response Graham. I'll have another go at it tomorrow and be a bit more forceful this time!

I've seen the various references to the skull-separation problem but, from the amount of oil on my boot after a ride, and the fact that there's oil on the front of the tacho-drive cover, I'm reasonably confident that my diagnosis is correct. We'll see though.

Having seen, and been impressed by, the high quality of your engineering in your restoration thread, I'm not at all surprised that any Brit iron owned by you doesn't leak oil. To be fair to my own bikes (Nortons), the leaks are from the gearboxes, not the engines so, in each case, a stripdown and rebuild with new seals should cure the problem but gearbox internals are a bit of a no-go zone for me so I suppose I'll just keep wiping 'em down and topping 'em up and live with it.

[48lesco]

There's also a rubber washer type seal in the cable at the engine end. It's part of the cable and not shown in the parts diagrams. If it's not present and sealing, there will be a leak where the conduit comes out of the "hex cap" for lack of a better description. There's also an o-ring under the tach drive fitting that's attached to the engine by a single flat-head screw but that one is obvious. If memory serves, you should probably detach the cable at the engine end, and pull the tach drive assembly out before you try to pull the side cover off. Gasket notwithstanding, that part should fall off once the 4 screws are removed...

[G-Man]

Al

Seems like you've got it sorted once you can get the cover off.

Let us know how you get on.

G

Many thanks for your quick response Graham. I'll have another go at it tomorrow and be a bit more forceful this time!

I've seen the various references to the skull-separation problem but, from the amount of oil on my boot after a ride, and the fact that there's oil on the front of the tacho-drive cover, I'm reasonably confident that my diagnosis is correct. We'll see though.

Having seen, and been impressed by, the high quality of your engineering in your restoration thread, I'm not at all surprised that any Brit iron owned by you doesn't leak oil. To be fair to my own bikes (Nortons), the leaks are from the gearboxes, not the engines so, in each case, a stripdown and rebuild with new seals should cure the problem but gearbox internals are a bit of a no-go zone for me so I suppose I'll just keep wiping 'em down and topping 'em up and live with it.

[Al Urquhar]

Following your reassurance Graham I had another go at it and it did indeed come off easily. As is usually the case, the reason it wouldn't come straight off on my first attempt was due entirely to my own stupidity - I hadn't bothered removing the HT lead from the plug and the bottom edge of the cover was fouling on the plug cap, giving the impression that the drive mechanism was somehow still hooked up inside (Doh!, as Homer would say).

Once the cover was removed the reason for the oil seepage became obvious. The sealing gasket is well knackered, broken into two pieces, with the whole lot being gummed up with silicone sealant by some previous have-a-go hero. So, it's a quick email to David Silver for a new gasket and hopes of a clean and dry right boot from now on.

Thanks also for your input 48lesco; the cable end seal is in place but I cannot check on whether or not the other O ring is fitted because the screw holding the drive fitting has been comprehensively mullered, presumably by the silicone sealant fan mentioned earlier, and I can't get the fitting off to check.

[48lesco]

"Comprehensively Mullered" is now my current favorite British euphamism. I hope you can somehow "get purchase" on that screw.
Thank You,
-48