951 DI no power / bugging

[metalmash]

2004 Sportster 951 DI

The boat is bugging a lot to a point that I can't get it on a plane if we are more than two people on the boat. And past 5500 RPM (after SLOWLY getting it on a plane alone in the boat) it bugs and miss. Fuel pressure is good (110psi), just cleaned/checked the RAVE valves. New plugs.

But we re-tested the cylinders compression and it's very low... +/- 90 PSI...
I removed the cylinders and they look good as well as the sleeve. Just ordered new rings/gasket.

Will that correct my problem?

 

[Phildoo]

The compression is awful and def your problem. Did you do another test after putting the head back on? Don't run it with that compression or you will do further damage.

 

[Lightningtruck]

Dumb question, but when you checked compression, did you open the throttle plates wide open? If not it will read low like that.

IIRC, anything less than 130psi is rebuild time.

Do you have any codes? Do a search under my user name - I had a DI Sportster with similar symptoms. But I had consistent codes and chased electrical gremlins and never did beat it before I sold the boat. 4TEC all the way for me these days.