I have a 96 xr600r which had a strange rattle as i just accelerate of idle in first gear(much like tappets but after setting time after time I sure they are spot on)and also becomes apparent when riding at a constant speed(neither accelerating or decelerating).I suspected piston slap or the connecting rod.After stripping down the motor and checking both I found the rod end to be within tolerance and the piston just out of tolerance.So a new piston pin and rings where fitted and still the noise persists.One idea that has come to me late at night is that it maybe exhaust noise.Anyone who has experience with the xr600r may be able to help with what is normal engine noise and what is not.:think
Did you check the clutch basket?..... the tines will wear, causing the plates to rattle within the basket. Also check cam-chain tension, the chain may be stretched beond its service limits.
Does the noise go like--- zit bonk ching-a-ling? :confused:
Or is more like zat,zat chunk-a-dang?:confused:
Seriously--now :)
Get a mechanics stethoscope and try to pin point where the noise is coming from more exactly.
If you do not have one then you can use something like an old broom handle cut about 24"inches long.
Hold one end firmly against different spots on the motor and the other end against your ear.
The noise will telegraph through the wood and you can pin point where it is coming from.
Then you can look at an exploded view of your motor and decide perhaps from the sound what could be possibly be making the noise.:)
If it only happens under load (when riding) and not while rev'ing the motor (and also considering it sounds like valve rattle), my guess is detonation caused by a too lean mixture off throttle or bad/wrong fuel. I'd make sure my fuel has sufficient octane rating and try cleaning the carb and checking jet and needle settings.
I also have a strange noise that i cant figure out. I called honda, and they said to check the bushing that goes in the clutch basket. They will somtimes bind between the shaft and basket.
Just to ease your mind, I owned a '93 xr600 that had the very same
noise you are talking about.. I too replaced everything (chain,top end, guides), but he rattle was still there...
So, I continued to race it for another two years with no
problems and ended up selling the bike with the noise.....