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The Bomber

2004 WR450F engine questions

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I am working on this bike for a friend. He has owned the bike since new and always taken good care of it. He trail rides but babies it as well. It has issues starting with the electric start.

I have checked the valve clearence and they are all in spec. on the low side of the spec. though. The spark plug looks good and the compression is at 80 psi. I couldn't find it in his manual but is this normal. My Honda has the auto decompression set up and is at 58psi.

I could not get all the timing marks to line up as the manual describes. At TDC the exhaust mark is above the edge of the head and the intake is below. They are just off a little. My asumption is that the cam chain is stretched. I also read something in the FAQ about the # of pins between the timing gear marks. His is 14 I read 12 for YZ's and 13 for his bike. His manual shows 14.

So is the compression ok for this bike or does it need a top end rebuild? What are your thoughts?

Any help would be appericated.

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