Hey folks I have the atv home now and was thinking should I do a compression test prior to taking the motor apart giving a before and after number.
All I have done to this point is remove the gas tank diconnect the oil and fuel lines. My idea for taking the top end apart was based on what the previous owner told me (thinks head gasket is gone that is why low compression and why it wont start).

How do I do a test (I will buy or borrow a tester)?

* remove plug, insert tester, pull cord? take reading?

What sould the compression be? I thought I read 110 or 120?
Thanks

 

Remove Spark Plug
Screw in Compression Tester
Make sure choke is off (not closed)
Hold Throttle wide open (I have found this to be very important!)
Pull cord several times until the gauge goes no higher. It might take 5 to 10 pulls.

Bleed off compression and repeat 2 more times. Average the numbers.

I will usuall drop about 1 oz of 2 stroke oil into the cylinder and then repeat the test again. A significant increase in compression (probably more than 20psi) will indicate bad rings.

I would say that if you are getting 110 to 120 psi, than you still have some life left in it. 90-110 psi will probably run if you don't care much about performance. Anything less than 90 psi means its ready for a rebuild.