Stock Compression

[Aka Kane]

I am going to look at a ski on Wensday. Should I check the compression? Or just make sure it runs and is powerfull on the water? The thing has never been rebuilt and it is a 650 all stock. What should I be looking for if I bring my gauge?

Oh yea and its a Superjet:woot:

Thanks

 

[accbr]

I'd check your gauge on a ski that you know is good just to get a baseline. Some gauges show 20 to 30 psi difference. Def check compression. Only takes 5 minutes.

 

[Aka Kane]

Anyone know the compression of the stock 650

 

[romack991]

Biggest thing is to check that the cylinders are within 10 psi of each other. I'd guess 140 or 150 psi but different guages can read differently, so biggest thing is that the cyliders are close to each other.

 

[demolition_x]

make sure the engine is warm when you test it. and hold it at full throttle. this is what my compression gauge told me to do.

 

[SUPERJET-113]

My printed OEM Yamaha 650 SJ manual says:
134 psi - cold cranking at sea level