1988-1994 Honda TRX300 Fourtrax, 1988, 1990-1994 TRX300FW Fourtrax Service Manual, Page 44Get this manual
MAINTENANCE
CYLINDER COMPRESSION
If the engine must be running to do some work, make sure the area is well ventilatedNever run the engine in an enclosed areaThe exhaust contains poisonous carbon monoxide gas that may cause loss of consciousness and lead to deathWarm up the engineStop the engine and remove the spark plug Install compression gaugeOpen the throttle all the way and crank the engine with the starter motor until the gauge reading stops risingNOTE The maximum reading is usually reached within 4- seconds
COMPRESSION PRESSURE: 1,250-1.450 kPa (12.5-14.5 kgcm2, 178-206 psi)
Low compression can be caused by:Blown cylinder head gasketImproper valve adjustmentValve leakageWorn piston ring or cylinder High compression can be caused by:Carbon deposits in combustion chamber or on piston head
BRAKE FLUID
Check that the brake fluid reservoir is fullIf the level is near the lower level mark, fill the reservoir up to the upper level markCheck the entire system for leaks if the level is low(1) UPPER LEVEL