JD 50 Compression Test

[Larry Bingham]

Did compression test on JD 50. 60 PSI on both cylinders. Seems low to me. What should compression be? I have IT Shop Manual, but can't find what it should be. All I can find is compression ratio.

 

[F-I-T]

(quoted from post at 03:56:42 11/14/12) Did compression test on JD 50. 60 PSI on both cylinders. Seems low to me. What should compression be? I have IT Shop Manual, but can't find what it should be. All I can find is compression ratio.

FSB 236 says at teh speed using the starter, a gas engine should read 118 psi, and an All-Fuel 91.5 psi.

Did you test it with the throttle wide open and both plugs out?

 

[Dodgeit]

(quoted from post at 05:56:42 11/14/12) Did compression test on JD 50. 60 PSI on both cylinders. Seems low to me. What should compression be? I have IT Shop Manual, but can't find what it should be. All I can find is compression ratio.

I had one that only read 60psi in both cylinders as well. Altough that seems low she pulled like a freight train so I just chalked it up to restricted air flow.

 

[F-I-T]

(quoted from post at 09:13:53 11/14/12)

(quoted from post at 05:56:42 11/14/12) Did compression test on JD 50. 60 PSI on both cylinders. Seems low to me. What should compression be? I have IT Shop Manual, but can't find what it should be. All I can find is compression ratio.

I had one that only read 60psi in both cylinders as well. Altough that seems low she pulled like a freight train so I just chalked it up to restricted air flow.

When you get one that low, unless there is a chunk of deposit in the intake area restricting air flow into the cylinder, you should squirt a couple pumps of oil in, spin it few times, and measureit again. If it comes up, it's likely the oil has sealed worn rings. If it stays low, suspect a leaking valve. Then it's time for a leak down test, and use a length of garden hose to listen through hose to determine where the air is leaking out.