Help on doing a compression test

[prairieboy]

I took the carbs off my 787 engines and sent them off to do a rebuild. I was going to do some more work in the engine bay and was going to check my compression. Can I successfully do a compression test with the carbs of. I know the butterflies are supposed to be wide open so thinking that without the carbs it would be the same thing.

Is there anything to be aware of and what about the fuel lines I pulled off?

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[Andy4k6]

I wouldn't do it with the carbs off, although a test is done with the throttle open there is still some restriction in the carbs and doing it without them on will give a false reading.

Andy

 

[Dr Honda]

Yes... as long as the rotary valve is still on the engine... you can do a compression check. Just ground the sparkplug wires on the terminals on the black box.