G'day Steve.
Just putting up my email reply for others to come on board.
G'day Steve.
It should have a 276, a 376 is a better carb. You didn't say what size. For your model (Star Twin) in a 15/16" 210 main, 25 pilot, 3 1/2 slide, .106 needle jet, 2nd clip from top.
If it's a 1", 270 main,30 pilot, 3 1/2 slide, .106 needle jet, 3rd clip from top. Make sure the float height is correct, level with the pip on the cover.
Steve replied that it's a 1 1/16"
I then replied.
1,1/16" is an A10 carb, I'd start with a 200 main. If it ran with a 100 main I'd say the fuel level is way too high.
Playing with bigger carbs on a 500 can get very confusing. My 51 A7 plunger has a 57 SS top end, 357 cam but lowish comp of 7.5:1, no air filter and straight through pipes. I run a 932 (1,1/4") concentric with a 190 main.
Cheers