2007-2009 Honda TRX300EX TRX300X service manual, Page 117Get this manual
CYLINDER HEADVALVE
CYLINDER COMPRESSION
Warm the engine to normal ope rating temperat ureStop the engineRemove the spark plug (page 3-8) Install the compression gauge with the attachment int the spark plug holeTOOL: Compression gauge attachment 07510- MB00101 or equivalent commerciallyavailable in U.S.AShift the tra nsmission into neutra lPull th choke lever down fully (open)Open the throttle all th way and cra nk the engi ne with the starter motor until the gauge reading stops rising The maximum read ing is usually reached wit hinsecondsThe cylinder COMPRESSION PRESSURE: compression 1,275 100 kPa (13.0 1.1 kgfcm2, 185 14.2 psi) specification is comparatively low Check that here is no leakage at the gauge because the connectioncamshaft has Low compress ion can be caused by: decompression device installed- blown cylinder head gasket