YZF 400 compression

1 reply to this topic
  • Rattler88

Posted February 28, 2005 - 07:45 AM


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

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  • 97zjguy

Posted March 01, 2005 - 04:07 PM


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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