750 cam chain.

well, it just had a tune up last spring. and nothing ha s been touched, so they should be good.

baldy110 wrote:

Just a thought but are your carbs synched? If your carbs are not synched the primary chain will rattle at idle. Depending on how far off the carbs are the rattle can get very loud.

Excellent point baldy 110

My '80 Z750 does this too, there's been one or two other threads about it. Definitely the primary chain (great big thing that attaches the crank to the transmission). They stretch over time but very rarely break, so people generally just tend to leave them unless the noise is bugging them. It's a long job to replace it! Ill-tuned carbs exacerbate the problem.

engine noise can be caused by a few things:
carbs out of sync
tensioner needs adjusted
spring inside of tensioner has lost a bit of it's strength
primary chain to the clutch basket lash

these bikes also make noise in the clutch basket from excessive mechanical lash.. pull in clutch lever at idle and listen for change of noise you may determine cam chain or primary chain
either way it is a noise that shouldn't scare you. it just is there all the time. lots of guys sell these bikes thinking there is a problem when there is no problem at all. I've gotten some sweet deals with that noise happening--- negoating for a bike that someone thinks is going to blow up is fun then you go sync the carbs and manually adjust the cam chain tensioner and ride the hell out of it laughing all the way

well, i did the stethoscope method, it's down low left side of the bike. (if your sitting on it) and is less worse when it warms up. Sounds exactly like the primary chain threads i have read. no change in noise if you pull in clutch or anything. only goes away more or less when you speed the rpms up a bit. so i will get the carbies synched to see if i can make it go away.

thanks for the help.