'77 CB750A sprockets & chain

Bikegeezer · Posted: Wed Jan 19, 2011 6:43 am Post subject: '77 CB750A sprockets & chain

Has anyone converted a '77 or '78 750 automatic to go from 630 to a 530 drive chain? The 15T front sprocket isn't available from any source, but Sunstar makes a conversion kit to install '76 sprockets. My concern is chain guard clearance.

Stu

Bikegeezer · Posted: Wed Jan 19, 2011 6:56 am Post subject: Re: '77 CB750A sprockets & chain

zjeppe · Posted: Wed Jan 19, 2011 12:23 pm Post subject:

Stu, as 530 is smaller than 630I guess clearance won't be an issue(yhen again I might be so wrong Embarassed

)As for conversion the first CBX vs Prolink goes from 630 to 530 painlessly maybe check there for fitting frontsprocket. I have my rearsprockets for the Bimota custom machined in hardened adonized alu, very nice, endless possibilties and not that expensive (30 euro)With nowadays chainquality one might easily go even lighter.My 200 hp S1000RR has a 525 that on 12.000KM only needed a slight adjustment Wink

Greetings & keep us posted,Jef.

05c50 · Posted: Wed Jan 19, 2011 4:44 pm Post subject:

Stu, if you just need the front sprocket, there's a couple new aftermarket sprockets available on ebay. I know a guy who swapped out the chains without any problems.

..........Paul

Bikegeezer · Posted: Fri Jan 21, 2011 10:51 am Post subject:

05c50 · Posted: Fri Jan 21, 2011 3:46 pm Post subject:

Sorry for the mis lead Stu. I was looking on ebay and saw the aftermarket ones listed, but I know that there is a guy that had an OEM nos spocket that he was trying to sell for a long time. I found it in one of the ebay "stores" when I was looking for mine. He listed it from time to time on the auctions, but it was always available in the store.

I do know a guy that retrofitted a 77 with a 76 chain with very little problem.

...............Paul

Bikegeezer · Posted: Fri Jan 21, 2011 6:09 pm Post subject:

Bikegeezer · Posted: Tue Feb 01, 2011 6:14 am Post subject: Worked out fine

I installed the stock sprockets and 104 link 530 chain for a '76 and didn't have to shim anything. Don't know what I was thinking. The teeth on a 530 sprocket are exactly the same width as on a 630 - only the distance between teeth and diameter of the rollers is larger. So no problemo, it all lined up perfectly.

Now, here's a tip for anyone else who needs to replace the 750A countershaft oil seal and outer trans cover gasket, both of which are unavailable. You can get a replacement oil seal that measures 3 mm thinner than the original. Install it just below flush in the case, and make sure the shaft bushing protrudes through the outer seal lip. I got the seal from Applied Industrial Technology. It's a TCM brand all rubber seal with double lip measuring 34x62x10. TCM part # 34x62x10TC-BX.

To install the outer cover with no gasket, first look at the pic below. The end of #10 protrudes from the hole in #1 and fits into a blind hole in the outer cover. The boss around that blind hole needs to be milled down around .010" to prevent #1 from binding up when the cover screws are tightened. Test first before installing the cover with sealer. With all cover screws tight, if the shift lever moves easily and its spring snaps it back when you release it, you're good to go. But if the shift lever feels like its binding (it's actually #1 that's binding), remove some more material from that boss inside the cover.

Clean the gasket surfaces of the cover and engine thoroughly, and smear a medium coat of Three Bond on the cover's gasket surface. Let it dry for around 10 minutes before sliding the cover on. Then tighten all 9 screws in a criss-cross pattern.

05c50 · Posted: Tue Feb 01, 2011 10:45 am Post subject:

Thanks for the info Stu. I had my side cover off a couple years ago and made a gasket from gasket paper (if I remember right), but it's good to have a number for a seal that Honda no longer supplies. I'm glad that the chain and sprocket worked out for you.

................Paul