Ok I need to know the speed of the jackshaft to axle ok so I have a 10 tooth to a 25 and on the other side of jack shaft is a 13 to a 55 tooth. I have 16 inch tires and I'm 150. Frame is about 100. Pounds. Engine is 212cc and or 3600rpm
What I would do is just get a new engine. You don't know what's wrong so you spend money on parts that work fine is just wasting your money.I would get a new one that runs new, looks mew, and starts new. Problem solved
Really if you want lots of torque and speed use a lawn mower shifter box. That's what I'm doing. You can use vertical or horizontal engine and have a 8 inch pulley to a 3 or 3 1/2. And if the transmission has a sprocket, use a 12 to 60
The other thing is it probaly doesn't calculate the wheight in the equation. Really 160 plus your frame you are losing some speed trying to hall all the wait. And you didn't fracture in the torque converter.
Well how big off hills. Steep mountains, small hills. Usually You would use a 1 to 6 gear ratio or 1 to 7. What speeds do you want if 35 or 30 use 16 inch tires