2003 CR250 clacking noise at 2/3s RPM with constant throttle

[kportingale]

Hey everyone,

My CR is making a weird clacking noise when my RPMs are about 2/3s in the RPM range with constant throttle applied. It sounds is very similar to the sound the exhaust valves make when they are opened then close and hit the stops, I heard this noise when i had the cylinder off and was opening and closing the exhaust valves. It started making the noise before i rebuilt the top end. I replaced the piston, wrist pin, rings, etc as well as the cylinder. I bought a brand new cylinder from honda. the only thing i didn't replace were the exhaust valves, i thought the top end rebuilt would take care of this noise. My pipe doesn't seal very well on the motor, (i definitely need a new one) not sure if that would add to me hearing something weird. When i had the cylinder off i checked the clearances on the crank and con rod and they seemed to be within the limits according to my manual. Not sure what it is so i'm just riding it till something blows up but i would appreciate any input because i would rather fix the problem before it leaves me stranded on the trail one day. Thanks

[erik_94COBRA]

Might check your power valve cables.

[YZ pilot]

when you check your powervalve cables make sure the pin that stops the arm that the cables attach to is still there.my 03 made a similar noise and turned out that the pin had fallen out .also on your pipe not sealing check the flange as they are known to break on 03's. good luck.