717 compression test

[sportster717]

Just purchased a 717 remanufactured motor(not sbt). I installed the new motor and ran it for 5 mins with a pre-mix. After that, I did a quick compression test to see how the motor would fair. I was only getting about 138 on both cylinders.

I was hoping for numbers in the 150+ range considering the motor is new. A mechanic told me that the engine will need to be broken in more and I should gain compression when everything has a chance to work itself in.

Does this sound right or did I just get a weaker motor?

Thoughts and thanks!

 

[El Toro 33809]

If you have only run it for 5 minutes, the rings have probably not "seated". It sounds like what your mechanic told you is accurate. Test the compression again after the proper break in sequence.

 

[Dr Honda]

If everything is absolutely perfect... it will show about 145 on a fresh engine. But... it's not uncommon for a brand new engine to need a little time before giving you a good compression number. Burn a couple tanks of fuel, and re-check.

 

[sportster717]

Sounds good! I will give it a proper break in and let everyone know what the new numbers are. Thanks for the feedback and the advice. It's really appreciated.

 

[Robj]

I had mine rebuilt and tested it after a few hours and had about 138 psi on both cylinders. Will test again once it is broken in. It seems to run really well with good power.