2002 60 hp 4 stroke

[adktrashman]

looking for what the compression should be for a 2002 60 hp 4 stroke

Thanks

[fairdeal]

The number I'm seeing: when it was new, 125 psi
At 68 F, throttle fully open, all spark plugs out

[adktrashman]

thanks that gives me a baseline

[boscoe99]

Minimum reference pressure per Yamaha tune up specification book is 139 psi. But the pressure seen on a gauge is based on a number of variables. Ambient air pressure and temperature at the time of the test plus the manner in which the test is performed, plus the accuracy of the pressure gauge.

Some Yamaha data is suspect however. One SM shows 125 psi for the F60 and 134 psi for the T60. Even though the blocks are one and the same.

In a reasonably healthy engine such as the F60 I would expect you to see at well over 125 psi with no more than 15% spread between the highest cylinder and the lowest cylinder. But if the motor starts well, runs well, makes good power and does not smoke or use oil, I would not go doing any major surgery even if the compression pressure is low or out of wack. If it is, then you can do a differential pressure check that will indicate what part of the cylinder might not be doing its job of holding pressure in. You can then determine what, if anything, might need to be done.

[boscoe99]

By the way, this ole boar hog loves his titties.