Hello, 

I have a sherco ST125 2011 and i am wanting more power, i was wondering what the difference is between the 125 and the 250 to see if i can just swap engines and possibly another tooth on the drive gear? the only difference i can see is the head, piston and con rod? am i correct in thinking this or is the carb different too? i have seen a post saying the carb was slightly different but only on the main jet. hopefully someone can shed some light on the situation.

Cheers

125 has same stroke than 250cc?

If yes, you can study parts numbers and see what change.

 

engine cases are different as well as crankshaft!

125's are quite sort after by beginners and those of a certain age(!) Would have got one myself if I had come across one of the right age/price/location.

I wonder if you would be better off selling your 125 on to someone who wants that size and power, and then looking for something that was a 250 from the factory...? Might save a lot of hassle too...?