yamahabob

Today i went out to the local canadian tire and baught myself a compression tester. As it doesne exactly tell you how to use it for a snowmobile, i put it on and gave it 1 pull and looked at it and it said 90.....i thought this was kinda low so i pulled it again to see what would happend and it went up to 120 and wouldlnt go any further.

Is this the proper way to check compression? I hope it is because i hope to hell its not 90.....

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smallengineguy

Give it full throttle and pull it 3 times to check it correctly.

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yamahabob

ok, so my compression turns out to be 120 on both cylinders.......my sled is a 99 yamaha v-max 600 twin with 7000 km on it.......what do you thik about the compression?

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Snow Freak

Well SEG always says anything under 120 is low, so it sounds like you are good to go!

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yamahabob

Ya, i think i remeber him saying that in another thread now that i think of it......
I stumbled upon something interesting on the net today.....aparently the 600 twins from 96-99 have poor compression from the factory due the the 1.4mm head gasket.....lucky enough i found http://www.maxxperf.com/Vmax_Twin_Gaskets.htm this website which sells a smaller one that increases compression quiet a bit..the gasket comes in .6 mm that need 91 octane fuel minimum or .8 that i can run regular fuel with...for $40.00 its sure worth the try and i might as well replace the exhaust gasket while im at it......

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smallengineguy

That compression is good! They'll run OK at 110 or so, but 120 is what you're looking for.

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1999 Yamaha Venture 500 touring
2001 Ski Doo Mini Z

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If I'm not home, CHECK THE TRAILS!

olezy_xlt

How about a 93 xlt (580)? All my pistons are at 110 and i was wondering if that would be low?! Im only 16 and the last thing i want is to have to pay for a new top end on a sled... Cause i gotta pay repairs out of my own pocket ( mommy and daddy dont do repair bills soo well ) lol!

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RJ Gleason

If you did the test correctly, it may be a good idea to try it with another tester, some of the cheaper ones are not accurate.
Did you test with the engine up to operating temp?

As long as the engine starts easily, don't be too concerned about it.

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