Keihin FCR Carb problems

5 replies to this topic
  • andrewbsavage

Posted April 11, 2003 - 07:07 AM


I have a 99 XR650L. I had it bored out and a 101mm JE piston put in. I also had a white brothers all around cam slotted and degreed in. I had a full white brothers e-series set up put on header and all. I also had a little mild porting done. I bought a Keihin FCR 41mm carb and my mechanic installed it for me. I don't think he set it up correctly though. From what I understand the accelerator pump should give quite a kick when I slam the throttle. The power gain has not been to noticible and am currios if there is a adjustment that was neglected on the accelerator pump or on another part of the carb. The menhanic said that the carb was jetted a little rich to be on the safe side. I am not to familiar with this carb and would be very thankful for any help I can get here.

  • Dutch

Posted April 11, 2003 - 08:02 AM


Sounds like a cool bike, is it a motard?
I'm sorry - I can't answer your carb question for you, but, the boys at the Blue Camp are running FCR's on their 4 stroke bikes and may give you some hints. One thing concerning "slamming" the throttle - you can stall a motor by opening the throttle too fast. CV carbs, like what came stock on your bike, control the movement of the slide to the vacuum needs of the rpm's you are running. Direct slide carbs give that responsibility to the rider and are not happy if you give too much too soon.
I have a TM40 pumper on my BRP. It is similar to your Keihin but the way to adjust the accelerator pump is different. The boys in blue should be able to help - they have lots of other problems over there :) so something like this will make them happy.

  • andrewbsavage

Posted April 16, 2003 - 06:09 AM


I am in the process of converting it to a motard, but the wheel setups are a little out of my price range right now so i am stuck wih dual sport tires. I still dont have this freaken carb set up correctly. Is here anyone out there that is running this carb on their 600 or 650? What jetting/needle position are you running? What are your mods and what altitude are you at? i know hat this bike can rip with all of he stuff that I did to it. the freaken carb is holden me up. :)

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  • Serpexc

Posted April 18, 2003 - 07:48 AM


Get with James Dean from the KTM and DRZ sides, he seems to know quite a bit about the FCR.

  • Thumpdup

Posted April 19, 2003 - 07:03 AM


I have that carb on my 650L. I have port polish, bigbore(102) 12.5/1 Compression, HRC cam, big header, pipe, etc... I will tear into the carb next week and post what jets are installed. I am currently jetted spot-on, except at sea level slight roll-off popping at 1/3 or less throttle. This is my 3rd 650L with these same mods and I can honestly say the FCR made a significant difference. You might want to try contacting SUDCO, as these people are experts on setup. I have never felt I needed to mess with the accelerator pump, however my interest is peaked now to tinker.

  • andrewbsavage

Posted April 23, 2003 - 07:55 PM


I would love to know what jetting you are running. I think I am getting a little closer I am now running 182 main and a 65 idle. I have not touched the needle and believe that the clip is in the middle. I will definitly give sudco a call.

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