question on compression

Hey does anybody know what the compression should be ( in psi) for a 78 kz650 SR?

According to my FSM it should be "156-185 psi with minimum of 114 psi and less than 14 psi difference between cylinders".

I see Bluemeanie's reply and raise you:
-Warmed up engine
-All spark plugs removed
-Battery completely charged
-Throttle wide open during testing

I'd do it twice, and the second time, add a little oil in the cylinders and make notes of the compression changes.

If you haven't made sure the valves are within spec, you could have a tight valve, and that would throw the readings off. A large valve clearance wouldn't make a difference on a compression test, unless it's a stuck open valve.

Do us a favor, and put your readings here.

my readings were 126, 118, 112, and 120. seems to me like that should be ok.

xblesseddeadx wrote:

my readings were 126, 118, 112, and 120. seems to me like that should be ok.

One below service limits and a greater than 10% difference between any two cylinders doesn't sound "ok" to me.

I think you should check/adjust the valve clearances then retest.