Chatter at 2500 RPM's

[Jamesp]

If the motor is in a bit of a strain I get a chatter at 2500 RPM's. It sounds to me like it is coming from the cam chain. From reading other posts it most are diagnosing the starter or clutch basket? It only happens right at 2500 R's , it doesn't happen before or after. Redid the shims about 1500 miles ago, rebuilt carbs, synced, new boots and O rings. What should I check first?

[blowerbike]

if i'm under a load on my kaw and roll the throttle open a little bit(similar RPM's) i get a detonation rattle, kinda like ball bearings or BB's in a can.
i added a gallon of 110 an tried the same routine and the sound was gone until i filled up again.
on the starter clutch and basket the sound is at a low RPM/idle and goes away when you rev it a little bit.

[Guest]

What should I check first?

Check why you are lugging a motorcycle engine to 2500rpm at big throttle openings. That thing is made to rev, let it run!


Mark

[tom203]

I get some chatter from the shock absorber mechanism in secondary drive if I sorta lug engine (mostly in second- if revs fall) and apply throttle.

[Jamesp]

I ride back roads to work. If I do not encounter traffic I only get the noise during take off. Since there are a lot of hills and turns traffic sometimes slows my progress and if I'm not right on top of it I can get to 2500 RPM's. Not that it happens all the time but thought I should inquire before it gets worse or I break something.

[Guest]

Not that it happens all the time but thought I should inquire before it gets worse or I break something.

Blowerbike might be onto something. What are you running for fuel? Try a bottle of octane boost in the next tank and see if the rattle goes away.


Mark

[Jamesp]

I almost always run premium. I used to have a mechanic that worked on my boat engine that convinced me to run premium in all my vehicles(except for my car). Not for the octane but for the higher detergent in the premium. I also put a few drops of Lucas and some green stuff to get rid of the alcohol. I will pick up some boost and give it a try though.


Thanks

[blowerbike]

i just cut in a gallon of race gas to my half a tank of premium.
on older bikes they tend to get a lot of carbon which can cause detonation.
in my case it may be because of a couple points added with a piston swap(just a guess).

[earlfor]

I ride back roads to work. If I do not encounter traffic I only get the noise during take off. Since there are a lot of hills and turns traffic sometimes slows my progress and if I'm not right on top of it I can get to 2500 RPM's. Not that it happens all the time but thought I should inquire before it gets worse or I break something.

2500 rpm is lugging the engine. Do it a favor and use whatever gear you need to keep the rpm above the 3500/4000 mark and I suspect you will find there is no problem. That engine is not designed to operate lugging around in 5th gear at 2500 rpm.

You're opening the throttle at 2500rpm and using large throttle increments. I suspect here is nothing wrong with the engine and the problem is the rider.