ATV Rebuild

Looking for some information on rebuilding the engine on a 2014 Suzuki 400 King Quad. It started leaking oil not long after I bought it, and I think it got hot when I loaned it out once. Bought the machine new and it only has 3500 KM on it. It runs like a champ, but there is a lot of noise in the engine. It almost sounds like piston slap....kind of a knocking sound. I adjusted the valves but that didnt help. Talked to the dealer yesterday and they didnt think it would be worth the money it would cost me to have them fix it. So my choices are to drive it until it quits or rebuild it myself. I've never rebuilt a 4 stroke before....how hard is it and will I need a bunch of specialized tools?? Anyone know where a guy could find a crate engine??

They are tough machines, I have a 07' king. 3400 miles all ez trapping miles lol. I know a guy that had his drain plug get cross threaded and leaked his oil out. To much money to fix it right, so he filled it with oil and runs it. Sounds like a diesel is all.

Is it possible to find a engine used on some trade listing? i have a Suzuki Eiger 400 still, 2003 and it runs like a champ. so its worth fixing in my opinion.
Lending never works out for the lender usually.