Author Topic: New member, new bikes, few questions  (Read 814 times)

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Offline KJ790

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New member, new bikes, few questions
« on: October 23, 2011, 08:09:10 PM »
Hey everyone, I just picked up a pair of '78 CB750 supersports and I am looking to start on a cafe racer build. The CB750 is new to me, but I've been reading up on here a bit and have learned a ton about these bikes so far. I do have a few questions though.

I'd like to ditch the comstar wheels and go with spokes while keeping the dual disk brakes, but a search on here showed that the swap is not all that easy. If I read correctly, the disks are closer together with the older K model spoke wheel than with the comstar wheel. From the posts I've read here people say you need to swap out the whole front end, but is it possible to use the '78 front end and brakes with an older spoke wheel and just shim the disks and/or calipers to line up?

As for the rear wheel I see that the '76 F model had a spoke rear wheel with a disk brake, and I read on here that the sprocket holder was wider on the 77-78 models. The suggestions here were to use the '76 swingarm, but why can't you just use the '76 rear wheel with the '78 swingarm and some custom spacers to get everything to line up?

My other question is about carbs. One bike I bought has the stock '78 carbs with accelerator pumps, the other has 064A keihins, which appear to be the stock carb from the '76 F model (correct me if I am wrong). Which of these carbs should I use? Any benefit to one carb over the other?
The most dangerous part of a motorcycle is the nut that connects the handlebars to the footpegs.

Offline Danno

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Re: New member, new bikes, few questions
« Reply #1 on: October 23, 2011, 08:49:12 PM »
the accelerator pump design is less fussy overall but has built in pollution settings that may have to be defeated to get it to work for you

the 064A keihins may have similar issues since they started the pollution settings in 76

I guess I would modify the 78 carbs if possible do a search for 1978 cb 750 carb settings

 I believe shimming the break calipres could be done but remember if they don't work right or come loose you are playing with your life that is why everyone will recomend changing the whole front end and not messing with that kind of thing it could get you killed if they fail after being messed with

I also believe that if you want to use the 76 rear tire assembly you have to use the swingarm or again the calipre mount may be wrong     so guys chime in I never keep any of the 750 models newer than 75 so I have not aquainted myself thoroughly
when you own a motorcycle the wife does not have to find you handy she just has to find you

Offline KJ790

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Re: New member, new bikes, few questions
« Reply #2 on: October 24, 2011, 03:09:48 PM »
Alright thanks, I think I'll stick with the pumper carbs on this one then.
The most dangerous part of a motorcycle is the nut that connects the handlebars to the footpegs.