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FCR and cold riding

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I noticed the first few weeks of having my fcr on that the bike started easy and ran great. Once the temps dropped below about 55 it seems like i have to ride with the choke on for a long time before the bike will idle. Does this seem normal? Its not uncommon for me to get about 10 miles away, pull the clutch in and have it stall or want to stall. Its a 39fcr from epic with an mrd/ssw pipe, 2000ft elevation, open top of airbox to the cdi posts, E base gasket. From epic the carb:

160 main jet

200 main air jet

emp needle

clip 3

45 pilot jet

no pilot air jet

2.25 fuel screw

ap mod

I ride the bike in the cold and i have a track day coming up soon so i want to make sure this is sorted out if its not normal. I havent touched any of the carb settings but i have to pull the tank this weekend to put in some E cams. Any thoughts?

Thanks

ps i did search for all kinds of things and i saw various results for hanging idles etc but nothing making note of colder riding issue when it seemed to run fine in 70F+

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Craig, i got the emn needle coming from epic as well as a flex jet to make those small tweaks easier:) It ran great in 70+ temps(which is should be most of this week and next) which is why i didnt want to go fooling with the fuel screw until i got some insight.

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Yep..All good...your needle controls your mid range...fuel screw helps control your idling..you originally posted that you had problems with your idle....

yup. I have LOTS of carb tuning experience, but all CV. I know all about the pilot/fuel screw circuit but having this trouble with just a small change in temp seemed very odd to me. I was curious if there was something odd about this carb and cold weather. Without an extended fuel screw or the flex-jet it's kind of a pain to adjust the fuel screw which was another reason i wasn't messing with it yet. 👍 I guess i just thought the small change in air density wouldn't have been a pilot circuit thing and i really wasn't expecting the "replace the needled" option. Once i get the new needle in and swap my cams over i will report back. Ill start with the emn on clip 3 and fuel screw still at 2.25 and see what happens. I don't think ill have any shortage of colder weather. Its 40F right now on my ride to work :smashpc:

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Ok...Get Eddie to send you the R&D Flex Jet....You will have clearance issues with a normal extended screw....And Good luck with your approaching Winter....:worthy:

yup i had the r&D flex jet from epic along with the needle.

I put it in and went for a ride yesterday. Fuel screw still at 2.25 turns, emn needle on clip 3. The ride started at about 1 and it was roughly 60F out. Bike fired up great, ran high idle on the choke and idled off choke just fine. Probably did about 60 miles of windy back roads for the first hour then about 2hrs off road on some trails. mostly 1st and 2nd gear since contiforce SM tires dont really do well with mud :ride:

Bike ran great until almost the end of the off road section. It started to have some stumbling issues at low throttle about where the transition off the pilot circuit is. Felt like it was rich. By this point it was almost 4 and the temps were right around 70F. It still ran great in the upper throttle range going 60+mph. Now on the trails even though i was in 1st and 2nd i wasnt putting around. It was mostly on the needle in the 6krpm range.

So i dont have a real conclusion but when the temps were below 70 the bike seems to run great. On the highway doing 65 there was no surging or stumbling(there was a little surging in colder temps with the emp needle).

The temps for the next 10 days look about 50-70F so i may throw the emp needle back in for the track day. I will at least have both with me even though im not looking forward to a track side fcr disection:) I havent done it but i think i can get the needle out with the carb in place 👍

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Something to try = turn the fuel screw in 1/8 to 1/4 turn and stay with the EMN needle..

Did you run thru this procedure....https://thumpertalk.com/forum/showthread.php?t=327405

yup i did in the morning when the temps were a bit chilly and it ran great. At the end of the trail when it started to sputter a bit I turned the the fuel screw in 1/4 but it didnt seem to make any difference. When i got home with the bike i dropped the idle all the way down and played with the fuel screw. 1.75 turns out the bike stalled. It was still happy at about 2.25 turns out. I didnt ride it today though. It seemed like it would do good if i dropped the needle one clip but it seems right now this needled taper is on the edge of the temps in the morning vs the afternoon so i dont want to tweak it too much since its only going to get colder. I will ride it the next cold morning we have and report back on it again.

thanks craig

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you need a "O" straight diameter,but it doesnt exist.

Thats good to hear :ride:

I can live with the emp needle but in the morning i dont like having to keep the throttle open at 2k through neighborhoods. I think the emn will work for my track day since its 8am-12 and i doubt the temps will be above 60. Here is to hoping though 👍

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put the E cams in last night and took it for a ride this after noon. Still stumbling and hesitating off the low end. Came back and swapped for the EMP needle(not bad when you dont have to pull the carb) and it runs much better. EMN needle it will idle fine. EMP needle, much better throttle response but still doesnt like low RPM. Ive settled at 2.5 turns out and i cranked the idle up(as a band aid i know) to about 1500-1800rpm. Anything below 1500 and it will stall it seems. I need to get more seat time, hopefully this weekend weather permitting, to try and get a little better tune on it.

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My FCR bike with the EMN needle idled great at 35 degrees after a few miles on the freeway. I have e cams and it will idle at 1200 rpms when cold and when warm it will idle between 1500 - 1600. Just to let you know how my bike runs. I have noticed it is more sensitive to temperature change then the stock carb.

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