Hello Howard, I cut the back out of the needle tube and it messed mine up, Just put a full tube back in and it feels much better, I am only 28mm carbs but mk2 cams and 9 to 1 pistons. I also found the stay up floats were touching the carb body above !! I had set the floats with petrol in to what Amals said but now lowered it a nat's. Cheers Bill.