750 four viabration and ticking problem.

My '82 KZ750H four has developed a ticking sound at idle, that sounds much like a loose cam chain, except I only hear it once in maybe each 100 rpm's or so, and when I hear it the engine slows for an instant. Adjusting the cam chain tensioner (it is manual) has no effect.

Further to that, the engine now has a bad viabration between 2K and 4K rpm's. I don't know if these two problems are related, but they started at about the same time.

I'm an okay mechanic but haven't worked much on motorcycles. What would you look at first?

polkat wrote:

My '82 KZ750H four has developed a ticking sound at idle, that sounds much like a loose cam chain, except I only hear it once in maybe each 100 rpm's or so, and when I hear it the engine slows for an instant. Adjusting the cam chain tensioner (it is manual) has no effect.

Further to that, the engine now has a bad viabration between 2K and 4K rpm's. I don't know if these two problems are related, but they started at about the same time.

I'm an okay mechanic but haven't worked much on motorcycles. What would you look at first?

Sometimes leaking voltage from the high tension circuit is described as a "ticking sound" as spark jumps to ground.

If the sound results from a loose cam chain and adjusting it has no effect, perhaps the cam chain and sprockets are worn.

Am uncertain as to meaning of the sound being audible only "once in maybe each 100 rpm's or so...."

"... when I hear it the engine slows for an instant..." could be consistent with possibility of leaking voltage from the high tension circuit causing the engine to "skip" or "miss" on an affected cylinder. The vibration between 2K and 4K rpm's might conceiveably also be related to any such skip or miss.

Have spark plugs been removed and base held against engine head with spark being visibly observed while kicking the engine over with ignition switch ON? Is there a consistent fat blue spark?

One technique for determining possible high tension voltage leaking is to have engine running at night or in a dark garage, and spray water mist from a hand spray bottle all over the coils, plugs wires, caps, and plugs, watching for any fireworks display.

Hardened original 28 years old plug wires (if applicable) may leak voltage even where the coils themselves remain perfectly serviceable.

Good Luck!