MM don't forget to use new, un-oxidized, main jets. As it is the leading edge of the jets orifice that is worried when the jets are sized with a polished burnishing tool. With very little oxidation, or
Bloom as Kevin Cameron likes to call it, accumulated on that leading edge of the orifice makes a big change in what the jet will flow.
The burnishing tool worries the leading edge, bringing the jet into size.
Jets sitting in a tool box for a period of time cannot be considered reliable as for the size originally marked on the jet.
In the old days AMAL
had two grades for jets, one for racing, and one for general street use. You could tell them apart where the street spec. jets have the annular
groove around the hex (similar to jets supplied under 376/100), and the racing (3326) ones the was no annular groove on the hex. After many years to oxidize, with any original 3326 racing main jet
it is only a guess how much fuel it will flow
If my memory serves me the racing were plus or minus 2.5%,
while the street ones we plus or minus 5% (but I could be correct on my % figures).