Pilot jets sorted the problem

[dickbarton]

Hi again,
I bought a Scorpion pipe, fitted it and took it off again when the initial 'bite' on acceleration went AWOL. I guess this means that the mixture is too weak again. Tickover is fine, in fact it runs much better and I can take it off choke sooner. I read that main jets need to be increased, but whats this shimming under the needle business? The stock needles come with different slots (according to the Haynes Manual), so dont I just have to choose a lower slot; effectively raising the needle?
Also, why would I need to increase main jet size AND raise the needle?
Please help.

Dickbarton

[GSF1200S]

Hi Dick,

Shimming the needles changes the fuel curve as the slide rises on throttle opening.  In other words, raising the needle will allow more fuel at a lower RPM.  However, it will not affect maximum feul delivery.  If you need more fuel you need a larger main jet/

Hope this helps.

Keith

[Red01]

US/Canada bikes don't have adjustable needles stock. Many other markets do, such as UK & EU. So shimming the needles is the way to raise the non-adjustable needles.

[dickbarton]

Thanks lads, in an imperfect world its refreshing to get not one but two perfect answers. I'm impressed.
Regards

Dickbarton

[Dave 02 1200]

I just received my Mikuni Pocket Tuner from Dennis Kirk.  It is a slide rule like device that makes it very easy to see the relationship between Main Jet, Jet Needle, Needle Jet, Throttle Valve, and Pilot Screw settings.  It shows specific jet size corrections required to maintain proper mixture for changes in ambient temperature and evevation.  I was surprised to see the cumulative effect of these variables and now understand why my Bandit is affected as it is by weather changes and location. ie Cooler weather makes it run leaner, higher evelation makes it run richer.  It might be the best $4.95 I have invested so far.

[edge of midnight]

From my signature you can see my set up. Af srews set to 2. 1/2 turns inners and 2 1/4 outers still to rich on primaries will try to get #20's that might help also note with this config std filter and 1 1/2 " airbox hole.  May look at Holeshots new backless airbox with K&N.