MOPED ARMY

might not be able to keep the same piston.

but i can tell you for a fact. my buddy and i ported his 1.5 hp cylinder.

matched the exahaust to the boss.

opened up the intake to 16mm all around. and he is running the same carb as you.

39mph all day. but takes a bit.

If you're porting the exhaust & intake ports use a dremel or drill w/metal grinding bits, but TAKE YOUR TIME! Stabilize the cylinder. Be meticulously gentle and don't overdue it...It's like carving a pumpkin with an X-acto knife in someone else's hand.

High torque top end, 15 Bing w 15 or 14 intake, and that pipe should get you to 40mph. Switch gearing to 16/40 for better results and jet in the high 60's.

If you aren't comfortable reshaping ports, just match the outsides of the ports to your pipe and intake. Make a smooth transition from where you dremeled on the outside down farther into the port, but don't mess with the port windows on the inside of the cylinder. It's a pretty safe way to get comfortable hacking away at your cylinder with a dremel.

I would also go at least 16 up front, unless you have something smaller than a 45 on the back. I'm geared at 16x45 on mine, and it'll do a solid 38-39 (although yeah, it takes a while to get there.)