NEED HELP!! 2002 CR250R making noise

[yankeefan4life72]

I recently bought a 2002 cr250 and I re-jetted it with a JD jett kitt.I followed all reccommendations that came with the kit.I also put a pro circuit full exhaust on it.Now I hear a rattling noise sometimes.it does not do it at idle.only when i am moving.mostly at low speeds.Like up to 1/4 throttle.I thought it was lean so i put a 410 main jett in.That did not fix it.Still making noise(pinging)??I also have an exhaust leak.where the pipe connects to the motor.it is not sealing tight.but i heard the noise before i put the pipe on.jd reccomended a 400 main jet.what do i do??I think i found the cure for the exhaust leak:http://www.denniskirk.com/jsp/produ...n&productId=p431283&catId=109&leafCatId=10901
but that pinging orwhatever it is is driving me mad.I dont want to damage my motor.please help
thanks

 

[RMASS]

was the noise there before you changed the jetting ? does the bike have a new or semi new o-ring chain on it

 

[KX02]

If the pinging is happening at 0-1/4 throttle a bigger main jet probably won't help you. More likely the air screw, pilot jet, needle position.

 

[yankeefan4life72]

i just put a new did o-ring chain and sprockets on it.and no the noise was not there before the jetting change.It is not lean(i dont think because there is plenty of oil inside the muffler)from burning gas i mean.like its rich if anything

 

[yankeefan4life72]

aalso it did happen today when i was at the track.I was getting on the throttle to clear a jump and i heard it ......but this was past half-throttle

 

[mx547]

if it's more of a knocking sound rather than pinging, it's the powervalve and it's normal for that bike.

 

[RMASS]

a new o-ring chain will slap out of stiffness on the swingarm, if your absoulutly sure the sound is coming from the engine ignore this. If not then TEMPORARILY remove the slack from the chain and ride the bike agian to see if the sound goes away and then readjust chain for proper riding slack. good luck !!