Leakdown test procedure

I looked in my service manual and searched the hallowed archives of the TT forum but I did not find a procedure for a leakdown test on my 03 wr 450. I understand it's the alternative to a compression test on a bike with an auto-decompression mechanism and I'd like to buy the tools so I can do it. just not sure on the procedure. I see the results posted in "%".


How do you do it? with a vacuum guage rather than a pressure gauge? % retaliative to what?


Thanks All!



A leak down test has nothing to do with compression testing.  That just measures engine compression peaks created by the piston seal.

It's done  to find out what part of the motor is 'leaking' by pressurizing the combustion chamber at top dead center with compressed air.

You listen for hissing or bubbling at the intake, exhaust, and crankcase (not so much on a four stroke)


If you hear hissing on the intake side, your intake valve train parts have some issues; usually an worn intake valve/seat combo.

If you hear hissing on the exhaust side.....


If you purchase a leak down tester, then you have even more precision measuring you can perform....




I did a google search and only found 50,000 hits...........

Edited by Krannie

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