[caldog101]

i am looking to buy a boat and it has a 1996 130 yamaha what should the compression be and how would i go about checking it ? thanks

[JB]

There is no spec for psi. The specs say all cylinders should be within 10% of each other. Typical is 100-125psi.

Ideally, warm the engine up first.

Remove all spark plugs.

1. Screw the tester into one cylinder. With the emergency stop lanyard out, turn the engine over at least 5 times. Note the psi.

2. Repeat #1 for each cylinder.

3. Lowest cylinder should be within 10% of highest cylinder.

[caldog101]

Thanks a lot for the quick reply JB

[caldog101]

just remembered JB someone told me that i need to keep the butterfly's open on the carbs ? is that true thanks again

[JB]

I don't think so, Caldog, but some do.

Try it both ways. My prediction is no difference.

[caldog101]

Thanks for all your help JB