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Is it possible (I probably did) to incorrectly install the decompression mechanism in a 2008 CRF450X

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Hi,

 

Its probably (not probably) my fault......

 

Just put in a new cylinder, piston, cam chain on my 2008 CRF 450X. My first after many years of XRs.

 

Thought I had a battery issue, could only start it with a fresh charge, charging system seemed ok, goes to 12.8 volts when running. And then I tried to kick start it.....way harder than my XR650R....I can get get it going but its tough to get it through TDC....when started it runs its fine.

 

Is it possible to install the the automatic decompression stuff incorrectly? Battery can't turn over the engine? I know there was a Honda Bulletin out about the pin breaking on the decompression mechanism but it was ok when I re-assembled the bike.

 

Thanks, Stephen (I'm in Senegal...you're my only hope!)

 

Edited by segge

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Yes, pull the decomp and pin back out and check. There is a notch in the pin that has to face correctly for it to work. You can check it without removing everything but I would just to make sure.

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I just checked out the decompression pin and it is functioning correctly. When I move the weight, the pin lowers and raises smothely and makes contact with the exhaust rocker arms.

 

The exhaust clearence was way off at .013. Could this make it more difficult to kick over or turn over the engine with the starter. This would mean that the exhaust valves would not be opening far enough by the decompression plunger to let the same amount of gasses out as a corrected adjust exhaust valve. Right? WOuld that be enought to do it?

 

Thanks, Steve

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I just checked out the decompression pin and it is functioning correctly. When I move the weight, the pin lowers and raises smothely and makes contact with the exhaust rocker arms.

 

The exhaust clearence was way off at .013. Could this make it more difficult to kick over or turn over the engine with the starter. This would mean that the exhaust valves would not be opening far enough by the decompression plunger to let the same amount of gasses out as a corrected adjust exhaust valve. Right? WOuld that be enought to do it?

 

Thanks, Steve

 

Yes. That could cause the timing of the decompressor to actuate late in the cycle causing too much compression to build. Reset the exhausts at .009".

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Thank you, thank you, thank you.....

 

I brought down the exhaust clearence to .0105, the engine turned over easily on a slightly weakened battery, great compression...yeah! I still have lot to learn...and I'm already 50!

 

Thanks guys...been overseas teaching for the last 20 years in Mali, Egypt, Libya, UAE and Oman..you guys have no idea how valuable and appreciated this site is. You saved my butt more than once! Got some pics posted on www.egge.us under the motorcycle link, some good rides.

 

Thanks again and take care.

 

Stephen

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