I have a big bore stroker 510cc CRF450X that I am in the process of converting to Sumo, and am looking for some gearing insight.
I have ordered a 14t front sprocket +1 from the stock 13, and am now trying to decide how small I want to go in the back. I am debating between a 39t, 40t, or 42t. The 39t will give me a top speed 104.3 MPH at 9000 RPM, and the 42t will have a top speed of 96.9 MPH with the supermoto wheels and tires, and the 40t at 101.7 MPH.
My question is, will the motor be lugging too hard in the low gears? I can always swap the 13t stock front back in place of the 14t to give me more accel, so I think I want to err on the tall side. I am leaning towards a 40t.
Any insight or opinions appreciated.