[Rjm1973]

First time poster, but I have used a lot of resources on this site with my recently acquired 2006 250. The tech articles discussions have been great, so thanks to all for that!

Here is my issue in a nutshell...I have very little compression in either cylinder despite having replaced the rings and honed the cylinders. I checked the end gap of the top piston ring and it is within spec according to the manual. I have a leak down tester and with the head back on the engine and no rockers/cams (therefore all the valves are always closed)... I have about 80% leakage on both cylinders at tdc. If I run the pressure up a little, I can here the air escaping into the crankcase past the rings (at least that is my assumption--I can't imagine how else it's finding its way out of the cylinders with all the valves closed).

The Pistons do not have holes...and the rings are installed per the manual. Letter side up in correct order, and the gaps are 180 degree apart.

At this point, I am contemplating that either the cylinders are out of round, or the piston ring grooves are worn preventing the new rings from sealing against the cylinder walls. Could it be anything else I haven't thought of?

The bike only has 8000 miles...but it's clear that it has not had an easy life. I'm certain it's been down at LEAST once.

Any help or insight you can provide would be much appreciated! I'd love to officially become a ninja250 rider...vs just a ninja250 mechanic