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Re: Compression test (archive)
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Posted by JamesM on August 23, 2001 at 15:07:42:

In Reply to: Compression test posted by Greg on August 22, 2001 at 05:50:06:

Over 170psi, under 210psi, no more than a 10% variance from the high to the low. Run the test again with a shot of oil (motor oil is fine) in the cylinder. If the number is higher, thne the rings aren't sealing well. Do the test with the engine fully warmed up, disable the ignition and fuel systems (unplug the relays next to the ECU in the glovebox), remove all 6 spark plugs, and hold the throttles wide open when cranking the engine. Make sure the battery has a good charge.

A leakdown test is a more comprehensive check. Less than 10% is very good. Less than 15% is good. Around 20%, you're looking at an engine rebuild in the near future.

You need a 12mm spark plug adapter. Most kits come with a 14mm and 18mm. Motorcycle shops will have the 12mm you need.

JamesM

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