Cobramike

[Cobramike]

Hey everyone this is my first post and I need help! I think my CB750 is in need of either cam or primary chain adjustment, the engine is making a chattering noise and I don't think it is tapet noise. I downloaded a 750 SOHC shop manual but it is a little vague on pictures and instructions on their adjustment and I like detailed inst. & pictures. I just got the bike which was found in a falling down shed on some abandoned property a friend bought. According to the realtor it had been abandoned approx. 15-20 yrs. Anyway I got it running and want to do things right before riding it and that is why I need all the help I can get from experienced owners, thanks.

 

[dirtdigger]

Primary chains are not adjustable it has a spring loaded tensioner. The chains will stretch with some miles and can make a noise but they all do it with age. The cam chain is simple to adjust. The engine is supposed to be set to 15 deg after TDC on cylinder 1 but you can just get it to TDC or a little after. Then loosen the locknut on the adjuster under the carbs on the back of the cylinder. Then loosen the adjuster bolt, there is a spring inside the adjuster that will tension the chain when the bolt is loosened. Then retighten the bolt and lock nut. If you just got it running I would go through and adjust everything. Valves, cam chain, points, sync the carbs, put some new plugs in it. Do an oil change too. These motors are air cooled so you will hear some mechanical noises, more than newer bikes or car engines. They make more noises than other motors too because of the extra set of primary chains too. Pull in the clutch and see if the noise lessens, if it does then it is primary chains.