Contessa build jet questions

[Nq50nicko]

Rite now running stock exhaust and carb with a 82 main. What do u guys think it should be at. Seems ok wot but closed to 3/4 throttle hesitates and kinda boggs down. Pipe is clean.have stock intake rubber tube on carb with foam filter on it.no box. Have a ct and waiting in the mail have a phbg clone black racing carb. But Wana break in with stock then setup the phbg carb. And any idea on the phbg carb jetings. 21mm. It comes with a 90 main and I think a 40 pilot.will run a foam uni type filter and may port the jug later and a a pg long or some kind of good exhaust in the future. Over winter prob. So any help will be greatly appreciated. I also have a nh80. I can steal the intake and carb off that if it'll run better.its bigger than the af16 stock carb and has a 90 main jet.let me know please. And thanks a bunch in advance. Ps going to get gears also 9.0 or 8.4ish. Wheelies like crazy rite now if I stomp on it a little bit. But holding off beating on her. For more than a few seconds. Have about 20 miles on the bore. And did about 10 to 12 full heat cycles before taking her on the road.

[Wheelman-111]

Greetings:

Flash 9 is similar Cortessa engine with stock pipe and carb also. It really likes the 90 jet still. Temps lately in the 353 range at 50MPH. I put the 92 in once and it wouldn't take full throttle - Way rich. The 90 went back in to stay. Because 0.02mm appears to make such a huge difference, I would believe that the 82 is much too small for 72ccs. Check your spark plug as it appears you don't have a temp gauge. I would expect it to be very light. Strongly recommend that CHT gauge, especially if you're moving on to a 21mm carb. That carb may require more than a 90 jet, perhaps closer to 102-105.

[Nq50nicko]

Yeah I got a cht gauge but haven't installed it yet. Wonder why the kit came with a 82 jet. My plug looks good.chocolate light tan/brown. Thanks for your input.

[Wheelman-111]

Greetings:

If you have notches in the jet needle, try it in the richer position (s). The Polini brand jet may be dimensionally different from Keihins. Gauge it if you have index wires.

[bonesv]

Yeah I got a cht gauge but haven't installed it yet. Wonder why the kit came with a 82 jet. My plug looks good.chocolate light tan/brown. Thanks for your input.

Because that jet is for an sk50 carburetor (pb style) which has a changable pilot jet. I'm in agreement with the suggestions given you already.