1995 SKS 440 Liquid Power loss

Hi guys. My sled will bog down after it warms up and then I have to limp it in. I feels like it's only running on one cylinder but I starts and idles perfect. Right plug is still white around porclin and appears to not be burning like it should. I replaced, cdi ignition box, stator, and plugs. no change. I plan on changing fuel filter, doing a compression test as well. Cylinders were both at 120 last year and plenty of zip left in them at 7,000 miles. I checked the crank seal and sprayed starter fluid and not change in rpms. Any ideas? You think right cylinder piston ring bad and looses compression?

Paul

1995 SKS 440 Liquid Power loss