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well i had some head work and the exhaust hot cam put on my bike.. put it all back together go to start the bike and i cant even kick it over. when u do get it started which is really hard it runs perfectly fine... checked timing looks good took the spark plug out and i can turn it over by hand.. what could be causing this problem??? decompression release broke? if so anyone have any information on how to fix the problem... thanks in advance...

steve

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Did you move the old compression release over to the new cam?

Did you check it´s function?

Did the pin come out properly when you activated the mechanism by hand before installing it?

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Did you move the old compression release over to the new cam?

Did you check it´s function?

Did the pin come out properly when you activated the mechanism by hand before installing it?

yes all that was done buy SF Performance in crystal lake IL... i didnt check the function of the pin i assumed everything was ok and just put it all back together...

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Reverify your timing.Count your cam chain pins.

i know its not timing... bike run perfect when u can get it to start.. when its on the compression stroke u can tell the compression release is not working its harder to start that my buddies 450 way harder... its coming apart today... ill take pictures and see if anyone can tell me how to fix the problem i have no idea how it works cuz like i said i did not take the compression release off the old cam and put it on the new one... that was in the deal with him porting the head and checking my valves is that he would swap the compression relese over and retime the cam

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Sounds like the decompression mechanism isn't working. Did you have your head planed for higher compression? If you did, maybe it is too high?

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There is a chapter in the manual that shows how to install the mechanism on the cam.

I can e-mail it to you if you don´t have it.

When the weight is in, or in the resting position, the pin should protrude past the cam lobe a couple tenth´s of a mm. The pin pushes down on the bucket and makes the valve leak compression. If it doesn´t reach the bucket it doesn´t work.

When you move it out (engine running) the pin should be below the cam lobe.

Pretty basic actually.

Take the valve cover off, turn the engine over so that you can see the pin. Move the weight and observe the pin moving.

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If it's not the compresion release it's the timing.all I know is last time I shimmed all the marks were lined up but it harder then snot to kick over but ran fine.I was one pin off on the exhaust.

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I bought my 06 used and it was really hard to kick over but ran great. I would have to stand on my stand to kick it. I found the exhaust valve lash was too much out of tolerance (.013") and the decompression pin was not moving the valve enough to relieve the pressure. When I shimmed it to .008", it worked great.

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I bought my 06 used and it was really hard to kick over but ran great. I would have to stand on my stand to kick it. I found the exhaust valve lash was too much out of tolerance (.013") and the decompression pin was not moving the valve enough to relieve the pressure. When I shimmed it to .008", it worked great.

thats exactly what im going through right now.... a 450 starts 10 times easier than my 250f right now...

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Sounds like the decompression mechanism isn't working. Did you have your head planed for higher compression? If you did, maybe it is too high?

no i didnt have it planed.. he asked if i wanted it done but i said no just cuz i dont feel like running U4 all the time.. stuff is way to expensive to be riding everyday with

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