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How to Check Compression

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My 07 450 xc-w has 175 hours and is starting to act a little out of character.

I have a repair manual but can't find anything in there on compression specs. I'd like to do a compression test but need the psi spec range.

Anyone have those numbers? THX

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I tested my 07 250 XCF-W and got about 115 psi. You need to keep kicking till the gauge doesn't rise anymore and use wide open throttle. Not sure about the 450, but I would think at least 100 psi.

Good Luck,

MrHix

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115 PSI is the magic number.

If it gets to much higher, it means the exhaust valves are loose and the ADC is not working correctly. If its lower, it could be several things. valves tight and leaking. Rings worn out or damaged or cylinder worn or damaged.

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L-vie said it well, 115 is the goal, hold the kill button while kicking as it can damage the coil to make high voltage and not give it a path to ground

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