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Discussion Starter #1
I have the carb sorted down low (46) and pretty good up high (180). I’m running an S&S air cleaner and an EV-27 cam with a stock head/piston/cylinder setup.

Bike runs pretty decent when it’s warm out, 50s and up. Below 50 it will at times take a long time to warm up, 3-4 miles at 50mph and every once in a while after 10 miles or so it will pop through the carb with part throttle on decel or I will leave a parking lot doing good and when I reach 2k rpms it will back fire through the carb and I will have to pull the choke further out. I put a .035 shim under the needle today and it seemed to clear it up but I haven’t in the past needed to shim needles on my sportsters. What is everyone opinions on running a shimmed needle with this setup? Like I said with the pilot jet, it’s dialed in. Just the thing always acted cold natured and the only cold natured part left is the midrange and I almost have it dialed in.


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Well, it depends on what the carb it is. As a rule with that set up you would move to a 48 slow jet for a lean pop in the low range. The needle hasn't pulled far enough to add extra fuel at 2000 rpm. And you can go as much a .050 shim on the needle, but that would be more effective for tuning up around 3000-3500. But it all comes down to what needle is in there.

My goto on an 80 incher is a 27094-88 needle 165 main and 45 slow. And cut three coils from the slide spring. Then I mostly tune with the slow jet.

Remember, any change to the slow side also changes the fast side.
 

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Discussion Starter #3
Well, it depends on what the carb it is. As a rule with that set up you would move to a 48 slow jet for a lean pop in the low range. The needle hasn't pulled far enough to add extra fuel at 2000 rpm. And you can go as much a .050 shim on the needle, but that would be more effective for tuning up around 3000-3500. But it all comes down to what needle is in there.

My goto on an 80 incher is a 27094-88 needle 165 main and 45 slow. And cut three coils from the slide spring. Then I mostly tune with the slow jet.

Remember, any change to the slow side also changes the fast side.


It’s an N86E. I tried a 48 in the CV carb but it wouldn’t idle drop when screwing it in and seemed a bit fat. I wasn’t sure if lifting the 86E needle was comparable to running the 88 sportster needle. 2k would be honestly a bit early with the carb pop but it’s most likely honestly closer to the 3k range since it’s around a shift point and I should be over 2k leaving a parking lot.


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