What's involved in replacing it? Does the motor need to be split or removed from the bike?

Thanks!

Just pry it out, be carful so you don't gouge the case. Then use something the same diameter like a socket or pvc fitting so you don't bend it and tap the new one in.

Sweet! Thanks, cousin!

its easer to take the engine and and do the job and when i did mine i took everything out and power coated it lime green and got some white fenders and it looked sweet wish i didnt sell it but now my yfz does the job