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07 450sx-f auto decompressor

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I have a 2007 450 SX-F which will not start ....seems to be a problem with the auto decompressor. As soon as the decomp lever starts to open the valve it snaps off the wide portion of the rocker arm , the valve closes with a VERY loud snap and the motor stops spinning --- compression won't allow it to turn over any more . Has anyone else run into this issue and if so what seems to be the fix ?? New cam nd rocker arm ?? Or ???

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same exact thing happened to me twice now, you cannot buy the decompressor separate so what you need to do is take the exhaust cam out and grind a flat spot on the little part that hits the rocker, i used a very sharp file but if that doesnt work for you carefully use a dremel. cover the whole cam with papertowels taped to it so you dont get any shavings on it. make sure when you take the cam out the lobes are facing outwards so there is no stress on the valves and rockers so it is a smooth disasembaly also. i also had to take some material off of the bottom of the counterbalancer weight thats on the opposite side so that the decopressor pin would make more contact, i would just make a little flatspot on the top of it for now and bold it in again and keep trying. remember that it is better to have to take it back out and grind a little more off than to grind too much off at once and buy a new cam. good luck with it... and remember to torque everything down to specs, middle four then outer four for the buckets!

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Hey --- Thanks for the reply--- your solution is just what i have done and I'm sure it will solve at least one of the problems. I work on motorcycles for a living but this is the first dohc KTM I have torn into -- it came in the shop with 98% leakdown and as I understand it , the bike has never started well from new. now that the decompressor work we shall see..... by the way --- you must have a gnarly file if you could file off the back side of the weight--- my file just skates across---no prob with the can though

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mine wouldnt start worth a crap either till i put it a jd jet kit, even a 42 pilot helped quite a bit. i have had to file the pin twice now so who knows how long it will keep doing it.

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