Pulling decom. lever while running bad?

Is it hard on the engine to pull in the decompression lever while it is still running?

If so, why?



It will kill the engine. You need compression to drive the piston.

When it dies, it will leave unburned fuel in the cylinder and may backfire and blow your air filter loose when restarted.

You decide. Does it sound like a good idea?

You also can hole a piston or bend a valve.

You also can hole a piston or bend a valve.

Can you tell me more about this? Didn't the ol' timers used to pull it to help them go down hill? I accidently pulled it while it was running the other day, and yes it stopped running, but no aparent damage was done. Did I just get lucky? Am I right in thinking that pulling the dec. lever opens a valve, the piston might hit that open valve?



Thats Bs..Let me ask you this...Does your valve hit the piston when you pull in the decompression lever to clear it out ..or crank it up??? the answer is no.. It is so easy to start teh engine without the kickstart while go down a hill.. I have a Wr250F and use the decompression to bump start it all teh time... and it has 6000 miles on it.. Now if you pull it while the motor is revved up..you will backfire..blow flames and make noise..so it is better to jsut use the kill switch there..And I ride with a bunch of ole timers that have been doin that forever..Just my 2 cents

I know for a fact if you pulled in the compression release on a YZ400F while it was revved that it would bend the valves. Several came into some of my shops that way. I don't know about now. Now if you use it to start a dead engine bumpstarting , there should not be a problem. But you don't use the compression release on a 4stk for the same reasons you do on a 2stk. On a 2 stk you release top end compression to kill power and allow the lower end compression to slow the bike down. You release the compression on a 4stk and the bike will speed up on a down hill, not slow down. I use mine for starting purposes only. Now if I had a run away engine with stuck throttle and the kill button didn't stop it , I guess I would chance the compression release , rather than lunch the crankshaft.



i have a wr400 and have inadvertantly pulled the decomp a couple of times at high rpm with no ill effects.

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