2004 crf 250x tapping/knocking

I have a question for anyone that might know about the 2004 crf 250x. I started my bike to let it warm up and I took it off the choke and it wasn't fully warmed up. The motor started making a chattering noise before it stalled out. I restarted the bike, idle was low, chattered again, it stalled and made a clank sound. Like the motor had kicked back. I tried to restart the bike and it backfired out of the pipe. I tried one more time, the bike started up and started making a tapping/knocking sound. I shut the bike off instantly, I pulled the valve cover off to make sure there was no problem in the top end. Everything looked fine. I spun the motor over a few times with the valve cover off. I placed the valve cover back on, put the coil wire back on, I started the engine and it was now running perfect, no noise or anything. I'm trying to find out what the noise may have been. Worried that I should booking for a bigger problem. It seems to run perfect right now though. If any input of what it could have been please let me know. Thanks.

Probably the auto compression release, when it operates the exhaust valves close suddenly and the valve mechanism makes a clacking noise.

i had a ktm years ago in which the de-compressor use to make a noise now and again,or stick which would be scary backfireing etc ! i just free'd the cable which operated it by lubing it every so often ....keep an eye on it but i would think thats what it is ..

Basically, it sounds like you took it off the choke too soon which caused the idle RPM to drop below normal and caused the automatic compression release to rattle. I never knew how much noise it made until I cut my air box. Now it sounds like a fork in a garbage disposal for a second every time I hit the kill button. It took me a while to figure out what it was making all that racket.


Kudos to you for shutting it down and investigating immediately, instead of standing there while your bike grenades.


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