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jet needle question

wvcoalminer

wvcoalminer

Member
I have a 1996 flstc bored 10 over 10.5:1 pistons EV 27 cam and a hypercharger i am going to rebuild my carb (cv 40) i bought a new slide as the old one was drilled with a 1/8 bit and i am installing a 88 sporty needle my question is should i drill the new slide 7/32 or leave it alone and do i need to shimm the needle and if so what size washer should i use and how many and by the way any jetting help would be nice
 
With the 88 sportster needle you will be on the taper much quicker as if remember correctly no accelerator pump in the cv for the sporty in 88 so the needle taper had to make up for it
There will be a wee bit of trial and error getting the carb set up for your bike i would start with a 46 slow and a 185 or 190 for the main jet washers are used for fine adjustment between jet sizes by lifting the needle further on its taper at all throttle positions
So if one main jet is too small and the next size up is too big lifting the needle a wee bit using washers gives a wee bit more fuel as steps or increments between jets

Brian
 
ok then i rebuilt my card 2 years using cv performance parts i use a 45 slow and a 190 main when i adjust the e-z just there is not much of a change so i thought a smaller slow may help and i have a small burp just off throttle should i leave the needle alone or will the new N65 from cv performance (built on the same specs. as the 88 sporty needle) help and what size washer will i use. ride free Johnny B i also run a dyna 2000i single fire
 
At the moment you consider that the slow may be too large if you add any washers to the needle then it would raise the needle and add fuel at all throttle positions including idle
So perhaps going down a size in slow with raising the needle is what is needed different washer thickness will give you different adjustments i always work by trial and error to get the right tune on a bike and no two bikes ever seem to be the same
drilling the slide will get the slide moving quicker but it will then hunt for its correct position for that throttle opening
Using the 88 sporty needle will add fuel quicker but as you already have an accelerator pump in your carb it may be too much fuel however if you have it and have time to spare it may be worth trying to see what the results are But you may have to change the slow and main jets to get the best out of the different profile needle

Brian
 
Fin has got you covered. I would add that the idle speed is very important when doing slow jet and air/fuel mix adjustments. Too much idle speed will take the fuel/air mix out of the picture. Specially with the tapered sporty needle. I would not drill the slide. I have never had good luck with a drilled slide.
 
wvcoalminer said:
and i have a small burp just off throttle
Click to expand...

Make sure you have checked for an intake leak during this process. I had an instance where it seemed like the slow jet was too lean (.048) and i had a small hiccup. Adjustment of the mixture seemed to have little to no effect on the idle or ridding the occasional cough leaving lights. Turned out a persistent intake leak was masking the correct low speed circuit needs. Here I was wanting to throw more fuel at it to stop the cough. Standing behind the bike told a different story though....... your eyes would burn it was so rich. Your gas mileage may indicate if it's too rich as well as too big a low jet will give you horrible numbers.

With what your running a 45 low and 190 or 195 main should be right in the neighborhood of where you need to be. Fin's suggestions will help dial it in further.

Don't drill the slide and the stock needle taper should be ok.

I ended up with a 45 low, 195 main and 2 small brass shims under the stock needle. My set up is very similar to yours with the difference being I'm running 9.5:1
 
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