G'day Michael,
I once asked the same question...here's a simple answer:
There is not "set" rule for jet sizes for a given engine size. You can't just go and ask for a set of "1776" jets. All engines and carb/exhaust combinations are different. You should check the colour of your spark plugs after driving. For example to check the main jet you would run at full throttle and then cut the engine and coast to a stop, then pull out the plugs and have a look. Black is rich, white is too lean and a nice even tan colour is spot on. Based on this you can play with the jet sizes until you get the right combo. There is so much more to jetting and carb matching than I even imagined or will ever know.
Try searching the forum as there is a lot on here about it as well as some good links to other sites.
Here's one:
http://www.aircooled.net/gnrlsite/resource/articles/jetting.htm
That said I'll take a back seat and see what the pro's say.
Cheers!
Toby
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