Main jet for PX221 WITH 26/26 carb, DSE Exhaust

Hi, after I change to 60mm crank shaft, I can set the carb to the best power, can anyone give me a help?

Before that I am using 210 cyclinder, 26/26 carb, DSE exhaust, with 148 main jet, every thing is good at that time.

But now, I am using the jet about 160...but it seem still not enough.

If you changed only the crankshaft and nothing else, it's impossible that you were fine with the 148 and now a 160 is insufficient! Probably there is an air inlet somewhere in the engine after you closed it (check all intake components, oil seals, especially that on flywheel side, and cylinder+head).

By the way, what gasket you used passing from 57mm to 60mm crank? Do you have a drt or COSA carb cap?