I just got the Vitos power piston in my blaster. It's still breaking in and feels really good through the higher rpms. But i have a wicked bog, sputter effect going on in the low end. It idles and starts great also. I know it's probably in the jetting but i'm no pro at this.
I have the Vitos jet kit. i tried a 290 main and the needle is in the 4th clip from the top. I think the new piolet is 32.5? As i said before it runs great starting around quarter to half and through the top...But it's also running really hot!..My premix is 24:1, it's got an fmf fatty, vitos degree key and uni clamp on carb style filter..the plug looks good, not wet (fouled) but it doesn't look to burnt either, kind of tannish i guess.
Can anyone tell me which jet, air screw, needle clip or anything might be off?..I just changed out the 290 for a 300 in hopes of keeping the temps down. A freak thunder storm cut my ride short so i never got any heat built up, but it still ran the same as before. Maybe i need more octane? It's got 94 in it now but it's also hicksville pump gas so who knows what it really is?...Any ideas out there?

first try putting the needle back in the middle position. that should halp. then if it still does ittry the pilot then the main to see witch one fixes your prob but i am almost sure its the nedle

I think it runs a litlle cooler now with the 300 main. I think maybe with 100 octane it will bring the temps down better. It still sputters though. Try the needle in the 3rd or 2cnd clip, (at 4 now)?....What about adjusting the idle speed and the air screw? Will that effect low end and hot temps. The airscrew is around 2and a half turns out. I have no idea about the idle screw. I just change it to hold a good idle.....Thanks for the help!!