Welcome to the forum its a great place to get your questions answered. the core determination is sort of up to the supplier of the new engine. I don't know what engines would fit for a swap out. I"m sure someone on the forum will have an answer for that. Keep in mind that swapping for larger newer may require some electronic work. I think I would go the crate engine route instead of swapping for a used engine. JMHO

 

Just did a cw motorsports engine on my 800s and was perfect so far 2500 bucks shipped to my door with upgraded common fail item parts ! 8400 miles from what I’ve researched is awesome for one of these , I’m no expert but mine had 3800 on it before she got tired of sucking in years of dust

 

Was the engine $2500 plus core? Was it factory horsepower?

 

I did the same thing with CW Motorsports. Very nice group to work with. I am just now riding off my first 10 hours. Only got 2 hours on it so far, no complaints. I'll change the oil at 10 hours and should be good to go. Heading to Hatfield McCoy 2nd weekend of November. I have a 2012 RZR S 800.

 

I'm in the same boat. Need to rebuild or replace my 800 s engine. I'm in SW Washington any engine builders in the Pacific northeast?