I got it here in the US, so their were no options to the carb, but it measures 7.5mm ID. So I guess this would be like the middle of the road. I've run about 1/2 a gal or better through it now, so this week I'll tach it again, with different props and see what I come up with. Really a sweet running little engine though. I wish all the 2 strokes had throttle responce like this one.