I do a lot of machine work and even reduce jet hole sizes but to do it right you need to test the flow before you start rejetting. I tried to work out a size system from the numbers on the jets but different companies use different systems and the numbers don't relate to for instance, the metric equiv. I originally thought that if a jet said 72 on it it was .72 mm which would equal .028" (.72 x 25.4) but it doesn't seem exactly right or work with all carbs.
BTW to reduce the size of a jet I drill the original oversize to.050 or 1/16" then solder a thin rod of brass the same size into the orifice. I then chuck it in a small lathe, center drill it and size it with a small drill. It's not as hard as it sounds. At over $9.00 each for jets from Yamaha it's worth it!
RobD
Posted on Sep 30, 2003, 7:28 AM from IP address 12.152.146.222
