TerminalVelocity

If properly set up, a big bore will run no hotter than a standard bore engine. The only overheating problems we have seen ***In properly set up motors*** is where the owner cock-rots (Neglects) his quad and runs low on coolent. We like these jobs as they add up to big $$$ in repairs. Any poorly set up motor is just a time bomb waiting to go off and may overheat, grenade, or otherwise take a crap at the furthest point in the dunes from where you parked. Terminal Velocity

To both of you asking questions - the type of gas you use will depend on your compression ratio and the type of riding you are doing. If you can answer these 2 questions I'd be happy to help guide you in your octane choice. Terminal Velocity

That shop does not know WTF they are doing. You should grab your parts from them and RUN. Of course the sleeve is Bigger! It's a Big Bore Sleeve. The original sleeve is cast in to the cylinder and must be bored out of the cylinder. This is precision machine work due to the tolerances it is necessary to hold to ensure a proper fit of the new sleeve into the cylinder. Additionally, port work MUST be done (again, properly) to ensure High Power Output and Long Life out of your new Big Bore Cylinders. I'll be watching this forum from now on, so if you have any further questions, post'em and I'll answer within a day or two. Terminal Velocity