I just got my 96 xp 800 running a few weeks ago. I used a short block from newer ski with my top end. I sent it out and had it bored .25 over and gapped everything to spec. I also filed a few thousands off the rave valve as it looked like they May have hit the pistons. I tested the compression when done and it was 130. With the old motor it was 175, so I was a little worried. I've ran the ski 10 hours now and it's sluggish. If I had to guess it's only running 50-52mph right now vs 59-61 with the old motor. I tested the compression today and it's 132 in both cylinders. If the rotary timing was off can it cause low compression? I'm leaning towards this or i got to thick of base gasket. I still need to check the squish. I never check the timing thinking it wouldn't be a problem. This is bugging me now, I want my speed back!