I'm going to build my thumpstar 125 with a 146 hc with a big valve head but I'm keeping my 22mm carb and I'm wondering if I should order larger jets now or if I should wait to see if it needs it? Thanks
It might not need to be rejeted. just because you put a bigger piston in it doesnt mean you need a bigger main jet. most of the time elavation and temp have more of a effect on jetting than piston size.