YZF 400 compression

Later on today I will be stoping by to look at a friends 99 400 and he

doesn't have a manual I was wondering what the cylinder compression should be for his bike so I can run a compression check before tearing

it down, and making him buy a manual.

It won't start after his son laid it over and the decompression lever is

bent, so theres a good possibility he damaged the exhaust valve plunger

cap, don't know for sure ? so I thought that checking the compression would

be a good place to start so if someone could please look it up and let

me know I will say thanks now to ya. :):):p

hey, i checked my clymer manual, and it says yamaha doesn't provide a required compression spec for this engine, but typically 170-180 psi is good if the engine was broken in properly. hope that helps.

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