FCR Carb Accelerator Pump Tuning [EXPLAINED]

How to adjust the accelerator pump on a Kehin FCR Carburetor.

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[bikelifesoldier]

Just about to rebuild my 06 YZ450F carburetor and this definitely helped. Built same carb on a 2010 KX250F but lucky everything was in spec that I overlooked and it ran beautifully. Thanks👊✌️

[lostcoastliquid]

Thank you! I have been helping a buddy tune his yz250f. I cleaned all the jets and made sure the whole carb was operating properly. Still bogging off the bottom when the throttle is opened quickly. I’m pretty sure the AP is the culprit. He’s already stoked because the bike is running better than ever but that bog is not cash money.

[AodanKeenan]

FANTASTIC EXPLANATION OF HOW THIS SHOULD BE SET UP! ON OTHER FCR MX VIDEOS, THE AIR CUT OFF DIAPHRAGM IS MISSING ALTOGETHER!!! WHY WOULD THIS BE? TANX

[mitaux]

Thank you, explained in a very good way!!!

[luckyaffpv]

Not enough likes. This video is great
Amazing demo. Thanks keep up the good work

[jettjensen]

Talk about an extremely helpful video!!! Thanks big time!

[reeceparlato]

1st person i have seen exsplain this so well

[danielcaratachea]

Can you tell me the name of the jet that squirts the fuel into the body ? I can’t seem to find it anywhere online . Thanks

[ScotEd-ow]

I have a custom built 43mm and someone added something to the fuel that corroded the carb it took a lot of work but I got it to run really good in the summer but even with the winter jetting it won't even start the carb and mid section didn't seem damaged in the least but the float bowl was the only thing it that the brass in the carb turns green now and I can't remove them to replace

[jeffkovacs]

Can you give me an idea of what you would need to tune my carb after I have done the rebuild and upgrades. I installed a new accelerator pump and mid body as well. I am having stall issues now because the idle adjustment screw was overly turned and had to be reset on the bike before I could reset the accelerator pump. It never had a bog issue before the rebuild but the pump got damaged due to carb/brake cleaner so, I replaced it as well. I’m in Miami. Could you look at it?

[tylermiller]

first off great vid! second i have a 2003 yamaha yz250f that im having some issues with the carb i bought a brand new one from RMATV and im getting spitting and sputtering in the mid range and can not get it figured out. WOT it does not happen also with the old carb it dosent do it either reason for chaning is sticky slide and broken off fuel screw along with a bunch of stripped out screws! any help would be greatly appreciated!

[Daac]

Great explanation. How do you adjust the duration of the fuel delivered by the accelerator pump? Mine is shooting for like 3-4 seconds and the bike drinks gas like crazy because of it. This is for an FCR39mx on a drz400.

[lifeofdan]

If you can help I’d REALLY appreciate it. I’ve got a 2004 carb on a 2006 engine. Cannot for the life of me get it to run off choke! It’s got all brand new jets. 42 pilot jet. Am I missing something? I’ve done all the gasket too, including the all the gaskets in the mid bowl

[Edd]

Just rebuilt the carb did the diaphragm and tuned the AP ran some gas through the carb off the bike and I don’t see the accelerator pump spraying any gas when I play with the throttle. Bike ran fine top end but low end it would bog. Any advice?

[juztfresh]

Hey great video quick question I’m getting a leak right at the accelerator pump when I open and close the throttle some fuel squirts out of that area and down the carb I located it to there and tested it any ideas I’m new to carbs

[drey]

How can I reset the position of that throttle disc with the idle screw to get a baseline Idle before even beginning to adjust the AP timing ?, I turned the idle screw not knowing what I was doing.

[GREYFIVENINE]

How can I make it squirt straight instead of squirting side ways?? Any idea?

[Frostbyte]

How to tune an fcr would be great. I’m new to them

[kingshyt]

If the ac pump was spraying to early in to the slide would it cause a stutter in acceleration about quarter throttle … I’m having this issue after replacing my ac pump

[MitchFlynnMatt]

Hey man, my accel pump arm looks different to yours, but the arm wont grip onto the throttle and wont move