at an idle there is a loud clacking..... but when i turn the throttle (in Neutral and in gear) the sound dissapears completely. I have searched the boards but did see anything that fit my description.

what could it be? the sound is horrible, sounds like a tank rolling down the street. but even under slight throttle it goes away. Doesnt matter if the bike is hot or cold same

 

Could be timing or alternator chain rattling, or both! (Or a few other things!)

Valve clearance may need adjusting to specs, Or carburettors may require synchronising,

As rough running from these two faults will cause timing/alt chain noise( internal noise is common for this model )

Although timing/alt chain noise may get quieter as the engine warms also.

Is it running great apart from noise?

Cheers

 

It sounds to me that the carbs are out of sync.

It only takes a little bit to create that effect. Yours may be out more.

The clacking is due to a strong cylinder pulling the timing chain, balancer and other internals followed by a weak one dragging them and then followed by the other two cylinders taking there effect on the internals. This power, lack of power, power, creates a slapping effect or as you say clunking. As you rev the engine, all four cylinders are pulling on the internals and there is no slack, the slapping would go away. If this is the problem I would get it fix soon as it puts stress on the internals shortening the life of the engine.

 

I have the exact same problem! My post is about a few threads lower. Please let me know how it turn out.

I will try this, since replacing the alternator chain is alot of work. Is there anywhere you can rent a carb syncronizer? Does anyone have any experience with the homemade ones I have seen online? Do they work?

Thanks,
tom

 

the bike runs great, just the clacking noise under idle. just started last nite.

could this be the cam tensioner? or something more serious.

 

How many rpm at idle

 

1k, i bumped it up to 1.5k and now only hear the clacking when i take off real slow from a dead stop

 

And you have adjusted the balancer shaft

 

no havent done anything yet..... how hard is it to do that?

 

easy, there is a good writeup on the forum.
https://cbrforum.com/m_161016/tm.htm

The hardest part of this job is removing the RHS fairing,