Randy Grein randygrein at
Sat Sep 29 19:08:26 PDT 2007

The flat spot is due to inappropriate needles. I ran several editions  
of the snorkelectomy (no filter stock pipe, stock filter & M4, M4 &  
BMC, Acropovik & BMC) and can say that the tuning varies somewhat  
depending on the pipe and bike. For example, did you know the jetting  
fore/aft changes between an M4 and Acropovik? Or even that there is a  
differential needed for the main jets?

Now honestly I wouldn't run desnorkeled on the street - I kind of  
like the quiet, and I'm getting over 50 MPG, but then I'm weird. If  
someone is interested I do have the factory kit with the BMC race  
filter, all set to go. (My race bike is on flatslides now, so the kit  
was retired.) It was pricy at $200, but I figure I got good use out  
of it and won't need it anymore. Make an offer....

Randy Grein, WMRRA #41

On Sep 29, 2007, at 6:35 PM, Jim Stewart wrote:

> 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...
> -js
> -- 

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