power valve not moving!!!

I have a 99 kx 250....every time I start it up the power valve does not move, and there is a awful metal hitting metal really fast sound/vibration. At first I thougt it was the piston/cylinder but I checked and they're stilll in good shape.

Does anyone know what could be wrong???

First, quit starting it! Metal-to-metal banging sounds mean something is being destroyed. Every time you start it you do more damage.

It sounds to me like the power valve main flapper has broken and is now hitting the piston. But you aren't going to know for sure until you start taking things apart. Pull the head and cylinder. If you don't see damage to the piston, pull the clutch-side engine cover and check the power valve governor. You also need to check for play in the lower rod bearing.

Well i only started it for a sec, to see where the sound was comming from, so I dont I hurt it too bad.

I'll go check all that suff out.

Thanks for the help.

Also when you kick the bike over, is the power valve supposed to move??

Because right now it does not.

know it shouldn't open when starting. it only opens when you hit a higher rpm.

Also when you kick the bike over, is the power valve supposed to move??

Because right now it does not.

The power valve doesn't open until about 6000 rpm. It won't move at kicking speed.

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