We purchased a 04 LT50A last year. I read about removing the restrictions. So I did. I removed the intake plate. Removed the second pilot and punched out the restrictor in the muffler. It ran great for while. Then the banjo bolt on the oil pump came loose one day and fried the rings. I had it bored and put a OEM piston and rings in it. It ran ok but it was running very lean. I started bumping up the main jet size. After a lot of screwing around, it never wanted to idle right. It was erratic. I  pulled the motor, replaced the seals, and re-sealed the case. I had the cylinder shaved clean and head milled .040. It now makes 120psi. Now it idles nice and it seems to run right. There's a 90 main jet in it and I still have grey on the plug. I looked at a Polaris and can am 50 and there main jet is a 75. How much bigger should I go?