Chattering noise in bottom end at idle

I have a '77 KZ650 B that I just rebuilt the top end on...Having carb issues that I am trying to resolve in the carb forum, but I have a question about a chatter at idle...I spoke to a Kawasaki guru locally and he suggested that it might be the "Hyvo"? chain? from the crankshaft to the tranny? the engine doesn't idle very smooth right now as I am trying to work out the carb issue...would that be a large contributor to the chatter in the bottom end? When I bring it out of idle, the engine smooths out and sounds great. Should I be worried?

if it isnt idling right everything is gonna be a little noisy especially the cam chain its all connected in there! good luck,happy wrenching!

Post edited by: wireman, at: 2006/02/13 21:41

Yes, that more than likely is the primary chain making the noise, and an erratic idle only makes it louder. It's pretty common and I would not worry.

Phew!!! Thanks!

I've heard that if the carbs aren't synched, it can cause the hyvo chain to make some noise.

Hyvo is high-velocity -- it's an internal chain that links the crankshaft and transmission input, rather than using gears.

Does the chain require any type of maintainance? Does it have some form of a tensioner? I can't see anything in the Clymer service manual about it...actually, it is pretty vague on any type of maintainance regarding the hyvo chain...I have completely rebuilt the top end of the engine...ie cylinder block, rings, valves, head machined, etc...the cam chain was in great shape, so I didn't bother replacing it. Everything else seemed tight. I have been having problems with the carbs, but that is because of a custom manifold and pods...maybe once I get the carb issue straightened out, the chatter will go away *crossing fingers*:S

Nope, no maintenance and no adjustment, all you can do is replace it. HyVo is actually a trademark name, it's a link plate chain
That style is used as a cam drive chain in the newer Kawasaki's (generally 80 and up), a timing chain in OHV V8 cars, and a transfer case drive chain in a lot of 4 wheel drive trucks, as well as a primary drive chain in your motor

Stell is bang on. My 650 did the same. Kawi mechanic said same thing. If you want to change it go for it, but not easy fix.

Yeah, as everyone said, they make some noise. Mine was extremely noisy when I first got my bike, with a bad ignition and filthy carbs, I thought I had bought a dud! Now I know the noise is fairly normal, but it's much worse when the engine is first started and cold. I like to have my hot idle around 1400 rpm so the chain doesn't make too much noise, it seems to like that idle speed.
These type chains will last forever, they stretch, but very difficult for them to jump. They die a veeery slow and noisy death! I used to drive a truck with a Hyvo chain linking the main and layshaft..when hot, it made a nice tick tick sound at idle. It was my signal that it was hot enough to take full power (it was a turbo engine).

Regards, Andrew

Dont want to step on anyones toes,but did you check your alternator rotor(magnets cracked or worse).Its a quick check just remove the left engine cover. Who knows it might be worth the 10 minutes to have a look.

Does it still do it when you hold the clutch in?

I never really paid attention to when I hold the clutch in, but it might be an idea for me to check. But when I bring it up above idle, it smooths right out with no rattle at all. I'll pull the alternator cover off and inspect as well.