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Old 09-30-2012, 10:04 AM   #69846
motolab
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Joined: Feb 2006
Oddometer: 2,170
Quote:
Originally Posted by eakins View Post
great visuals!

how is it people say the ktm needle works better than an oem needle shimmed? i have 2 washers under an oem needle and was thinking about a ktm needle. i see a wider ktm needle and that means less gas at the oem needle assuming the same resting position.

even the fp needle is wider. the only advantage those 2 have is clip adjust-ability but washers under the factory needle work just fine to raise the needle and thus more gas...plus the factory needle is thinner as lets more gas through. i see it being the best oem shape option. plus the fp & ktm needle are longer and sit deeper in the carb, less gas, than oem.


am i missing something here???
Aside from the clarification by Rumlover about exposed area (thanks Rumlover!), also note that except for the DJ needle, the chart seems to be arranged with the tips even, which isn't all that useful. It would be better to look at mxrob's chart with the diameters, simply because the measurements are all taken in relationship to distance from the third clip (when adjustable).

As shimming the needle clip preloads the slide spring beyond standard, it results in lowering the slide rather than raising the needle. I would not shim the needle clip unless the goal is actually to lower the slide for a given intersection of throttle angle and rpm. Note that the additional preload from shimming the needle will also make the slide come off the stop at a later point in terms of rpm and throttle position (i.e. more velocity will be required to get it to come up off of the stop).

Regards,

Derek
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