Jim Stewart js at
Sat Sep 29 18:35:51 PDT 2007

Ernest Montague wrote:
> OK guys, there is a stock formula that used to work pretty well for gen 
> one carbs with a race pipe and aftermarket filter or opened up stock 
> filter....
> Anyone remember?
> 148 mains?  I do remember shim the stock needles 40 thou.
> Ernie

Hi, Ernie -

After half a million dyno runs, Jack Roe developed a formula for desnorkeled 
airboxes and race pipe: 152.5 mains, 17.5 pilots, two shims (.040") under the 
needle, pilot screw at 2.5 (I think). He later recanted and recommended the 
stock 15 pilots and 3 turns. He also recommended drilling out the bleed hole in 
the slide, but that didn't seem to make any difference on my bike.

It turns out that the desnorkeled airbox is a bad choice for a street bike - big 
flat spot at 5K or so. Maybe it works for a racebike - others can surely tell you.

I have my own preferred settings for a street bike, but you're interested in 
your racebike I assume...



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