71 thunderbolt 650 won't plane

[Jplay5383]

I just acquired a 71 mercury 650 thunderbolt 4-cylinder. I can't get it to plane out most of the time. It starts and runs good too. When I hook the out drive up to the muffs it sounds great but in the lake just can't get it to plane out all the time.

 

[jbcurt00]

Are you running the right prop and reaching optimal RPMs on the motor?

If so ^^^, the motor may not be the problem.

What boat did you put it on?

 

[Mi duckdown]

First I would do is check compression

 

[jbcurt00]

First I would do is check compression

By all means yes ^^^

I sort of figured if it was bought as a running motor, compression would have been part of the pre-purchase inspection.....