I have a 1992 trx 250x, and i change the sprockets to 14/36; when it had 13/38 on it. The problem i ran into was i was running 56-57 mph before i swapped them and now im running 56-57 mph still. I am running 20-11-9 on the back and front too. what could be the problem?


P.s. i built the motor back with a wiseco high dome piston that made the compression 12:1 and i run premium gas.

 

If those are the only modifications, your engine isn't going to pull a gearing that tall.
Stock would be a 2.92 but you now have a 2.57......that is a big jump for a basically stock engine.