Hi, welcome to the forum, some suggestions for your RZR:
Do the Pinion Nut repair. The stock pinion nylock nut can come loose without warning destroying your rear differential.
The Razor 800 & 800S Pinion Nut Repair Video by Les Hansen (Pullerguy) Hopefully, this video will help those many Razor 800 and 800S owners with doing the pinion nut repair on their rides. We have Pullerguy (Les) and Pirate (Stuart) to thank for their engineering expertise in developing a tool...
Install an oil pressure gauge. There is a Pressure Relief Valve (PRV) that can stick open or closed. If it sticks closed it can blow out the oil filter or over pressure the hydraulic lifters causing the valves to not completely close. If it sticks open it can cause the lifters to clatter and starve the cam and rockers of lubrication. You won’t know unless you put a gage on it, mine was too high.
Make sure there are no leaks in the intake tract, the air cleaner housing is frame mounted and the engine is rubber mounted, sometimes the rubber boot gets pulled off of the throttle body because the motor moved. Don’t use a foam filter.
Get a spare belt and practice installing it in your driveway, while you have the cover off use compressed air to blow out the clutches and inspect them. The belt is difficult to get to so you want to make sure you have the correct tools and the know how before you have to do it on the trail.
Lots of information on the forum, just use the search function.