I just put a set of v force reeds in my 2000 mxz700 and noticed on slight scorring of the piston on the pto side. I then did a compression test and got 145 across both cylinders. I'm hoping the jug is fine and all I need is a piston. Should I change both pistons and rings? I'm on a budget and would like to get away with one if possible.

had the same problem on my 02 mxz800x....ended up being covered under warranty. replaced both pistons,rings and crank seals as well as the y pipe and exhaust!!! considering i brought it in for a leaky base gasket i was a bit surprised!!
you gotta love that 2nd year engine warranty!

Do you have a picture of the scoring?

I've never taken out a piston that was 100% perfect,
so you might be ok. 145 lbs of compression is pretty good.
What did you have new?

Do you notice any flat spots in running it? How many miles
on the sled? Is it time for a rebuild?

On my 2000 700, I was around 142 lbs with my gauge.

If you were to replace the piston, I'd replace both sets
of rings at a minimum.

If this is stock, and few miles on the sled, and I'm on a budget,
I'd run it through the season and rebuild it over the summer. At
worst, you'll be down a bit on power, but I can't believe it with
the compression.

Could have been water on intake or lack of lube. Is your oil pump
turned up? Those years were known for eating crank bearings.

Good luck.

intake scoring is a very comen problem its from water and considered normal.

snow ingestion..happens all the time. :cool:

Thanks for the info. I'll ride it as is cause it runs gooood!

SOUNDS LIKE COLD SCORE LET YOUR SLED WARM UP BEFORE YOU CAN THE THROTTLE

If its slightly scored..its perfectly fine...dusted from snow, water, or anything else..alot of times the exaust side is scored more. Wont hurt anything for a long time.

145 is plenty good for a Comp ratio. Ive run pistons that were way worse on my dirt bike...they actually hold up pretty good..