Keihin Cr Special Carburetor Tuning Manual

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I recently had the pleasure of performing a complete frame down rebuild on a 2007 CRF250R that came to me with an intolerable bog issue when the throttle was stabbed from idle or low RPM (both when riding, and on the stand). After the head was rebuilt, and the engine freshened up with a new piston and rings, the lean bog was still there. There is very little in the Honda service manual regarding the accelerator pump circuit, or leak jet, so I documented the process that I used to solve this problem, and decided to share.

The information presented here is applicable to any brand of motorcycle that uses the ubiquitous Keihin FCR carburetor.

If you are experiencing the dreaded “lean bog” when stabbing the throttle on your Keihin FCR carbureted dirt bike from low RPM’s you don’t need to buy expensive “fixes” such as the Boysen Quick Shot or the R&D Racing Power Bowl… you simply need to tune your carb using the adjustments that are already there… I'm not saying that Boysen or R&D hasn't come up with a valid fix, their products certainly make it much easier to properly adjust the accelerator pump to tune out the bog, my opinion is that in most cases you don't really NEED those items to fix the issue... In the case of this particular bike, it only needed a $10.00 leak jet and the problem was solved.

Many thanks to Marc Salvisberg, founder of Factory Pro Tuning, for teaching me the finer points of using dynamometers and tuning carburetor equipped engines.I'm sure he still disagrees with some of what's here (my dislike of changing float level, and even suggesting that one use a lambda sensor, for examples.), but this version of my FCR tuning manual is a lot better than the ones I wrote. Keihin carburetors are only legal in California for racing vehicles, which may never be driven on public highways or waterways. Keihin carburetors are designed to be used with normal pump gasoline. Fuels that contain over 10% alcohol content may damage parts in the carburetors. This may prevent the carburetor from functioning properly.

Please follow along while I present my case :-)

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Keihin Carb Manual

  • 2004 05 06 Suzuki RMZ250 RMZ 250 04 05 KX250F Engine Keihin FCR Carburetor Carb

    <p>This is a used Keihin carburetor from a 2004 Suzuki RMZ250 that I am parting out . It does show normal wear and could use new screw to hold the bowl on and it is missing the throttle cable cover. It does function smoothly. I am including the throttle cables as seen, but please look at the pics where you will see one is needing replaced. This should fit 2004, 2005, and 2006 Suzuki rmz250 bikes and 2004, 2005 Kawasaki kx250f bikes, but please check your bike before buying. Comes as is and as seen in the pictures. I always suggest cleaning any carb before installing. It could use a good cleaning since it has been sitting unused in my shop for a couple months. Thanks for looking. </p>
    Brand: Keihin
    $17.59 shipping
    Type: CarburetorWarranty: No WarrantyCustoms services and international tracking provided

  • Keihin Carburetor Carb Intake fits 1989 Honda CR125 16100-KZ4-000

    Removed from a running 1989 Honda CR125 2-Stroke. This part should fit other Honda models & years but check with a dealer to make sure. Request more photos if you need different angles or details. Fastened up well.
    Brand: Keihin
    $16.82 shipping
    Type: CarburetorWarranty: No WarrantyCustoms services and international tracking provided

  • 1999 KAWASAKI KX250 OEM KEIHIN PWK CARBURETOR CARB CARBURATOR ASSY KX 250

    For Sale is a Used OEM Keihin PWK Carburetor Assy off a 1999 Kawasaki KX250.
    Type: Carburetor
    $31.15 shipping
    Customs services and international tracking provided

  • Harley keihin carb carburetor spigot mikuni screamin eagle

    Spigot style keihin carburetor stamped pa40c ce12. Makes a good carb. We have a ton of motorcycle parts. Your patience is appreciated.
    Type: Carburetor
    Was: Previous Price$75.00
    Customs services and international tracking provided

  • KEIHIN PJ CARBURETOR! 87 88 89 ktm 250 mx sx mxc intake carb fuel float bowl

    It's used, so don't expect it to be perfect. It needs to be rebuilt. The above referenced item is from a1989 KTM 250. Do your own research before buying. 250r trx250r lt250r drz400 rmz250 yfz450 z400 ltz400 trail blazer scrambler magnum raptor 660 700 350 blaster warrior tecate lt230 lt250 ranger trail boxx bandit 600 1200 boulevard c50 intruder 450r 400ex banshee vulcan cb650 cb750 prairie lakota 300ex 250x predator rmz450 crf450 foreman recon rincon yamaha honda kawasaki suzuki ktm harley davidson ducati.
    Brand: Keihin
    $55.40 shipping
    Type: Float Bowl

  • Keihin PE Carb Round Slide carb carburetor honda odyssey fl 350 fl350

    Carb for fl350.
    Brand: Keihin
    $32.97 shipping
    Type: CarburetorWarranty: No WarrantyCustoms services and international tracking provided

  • 2004 Suzuki RMZ250 Carburetor Keihin FCR 37mm 04 05 RMZ 250

    Carburetor Keihin FCR 37mm 2004-2005 RMZ250. 2004 Suzuki RMZ250.
    Top Rated Plus
    $17.43 shipping
    Brand: KeihinType: CarburetorCustoms services and international tracking provided

  • 04 05 HONDA CRF 250 R CRF250R CARBURETOR KEIHIN FCR FLAT SLIDE CARB COMPLETE

    KEININ CARB NOT AFTERMARKET JUNK OFF A 05 CRF 250 R
    Type: Carburetor
    $30.92 shipping
    Customs services and international tracking provided

  • 74 Honda MT 125 used Carburetor Intake Fuel Genuine Keihin

    Will need a cleaning and/or rebuild to ensure everything is correct for your application. 74 Honda MT 125. Photos of Used parts are generally of the item listed unless there is a quantity more than 1 available.
    Top Rated Plus
    $20.34 shipping
    Brand: HondaType: CarburetorCustoms services and international tracking provided

  • CR KX YZ RM KTM 250 500 KEIHIN PJ 39MM CABURETOR 39 MM PJ CARB COMPLETE

    THIS IS A KEIHIN 39 MM PJ CARBURETOR IN GOOD SHAPE. CARB IS CLEAN IN AND OUT. CHOKE DOES NOT SEEM TO WORK PROPER AND MAY NEED TO BE REPLACED. THE REST OF THE CARB SEEMS GOOD. WE BELIEVE IT WAS REMOVED FROM A LATE 90'S KTM 300 BUT NOT A 100%25 SURE.
    Type: Carburetor
    $30.38 shipping
    Customs services and international tracking provided

  • 2000 Kawasaki KX250 Keihin PWK TPS Carburetor Carb Intake 1999 2001 2002 2003

    This is a Kawasaki KX250 OEM Keihin PWK Carburetor. Overall good condition, ran well. Cleaned and reassembled. Throttle cables and throttle included. Look over pics.
    Brand: Kawasaki
    $31.81 shipping
    Type: CarburetorCustoms services and international tracking provided

  • 98 KAWASAKI KX 125 KX125 CARBURETOR OEM KEIHIN PWK CARB RIFLE BORE CARB 1998

    THIS IS A 1998 KAWASAKI 125 OEM KEIHIN PWK CARB. CARBURETOR HAS BEEN PORTED, POLISHED AND RIFLE BORED BY REP PERFORMANCE. WAS REMOVED FROM A GREAT RUNNING BIKE. CARB TOP IS BROKEN AS SEEN. STILL WORKS WELL WITH BOOT DOWN.
    Type: Carburetor
    $29.62 shipping
    Customs services and international tracking provided

  • KEIHIN CR29 spigots, intake adapters

    Up for sale a set of spigots for Keihin CR29. 4x Aluminium spigot custom made - O.D.=40mm, I.D. on motorside=34mm, I.D. on carbside=29mm, total L=30mm - only for CR29.
    From Poland
    $5.00 shipping

  • Keihin PWK38 PWK 38 Genuine Air Striker Carb Carburetor TRX250R CR KX RM YZ 250

    New Genuine Keihin 38mm PWK air striker carburetor. This does not fit all makes and models and you may or may not need a different throttle cable. You must make sure your intake will accept this size carb.
    Brand: Keihin
    $29.33 shipping
    Type: CarburetorCustoms services and international tracking provided

  • 1984 1985 Honda XR250R XR 250 R OEM DUAL KEIHIN CARBURETORS CARBS For Rebuild

    Check and make sure they will work for your bike.
    Brand: Keihin
    $31.67 shipping
    Type: CarburetorWarranty: No WarrantyCustoms services and international tracking provided

  • 1995 SUZUKI RM125 OEM KEIHIN PWK MODIFIED CARBURETOR CARB RM 125 93 94 95

    1 995 SUZUKI RM125 KEIHIN PWK CARB. CARB HAS BEEN MODIFIED TO INCREASE AIR VELOCITY INTO THE ENGINE. JUST LIKE YOU, WE DON'T LIKE TO WAIT FOR PARTS WHEN WE CAN BE RIDING!
    Brand: Keihin
    $17.67 shipping
    Type: CarburetorCustoms services and international tracking provided

  • 1982 HONDA XR500R XR 500 MOTOR CARBURETOR CARB KEIHIN OEM

    Removed From: 1982 Honda XR500R with 22,853 miles. Will need to be cleaned and or rebuilt prior to use.
    Type: Carburetor
    $27.83 shipping
    Customs services and international tracking provided

  • 1999 CR250 CR 250 OEM KEIHIN Carburetor Injector Carb Intake Throttle PWK 00A

    Condition: Genuine OEM Keihin PWK 00A Carburetor including Cable and Twist Throttle. In GOOD working condition with no cracks breaks or repairs. All bolt threads intact. Ready to install. 1999 Honda CR250R.
    Brand: Honda
    $71.75 shipping
    Type: Carburetor

  • 1983 Honda Shadow 750 Vt750 Carbs Carburetors Keihin 7AA OEM

    Removed From: 1983 Honda Shadow 750 VT750C.
    Brand: Honda
    $25.53 shipping
    Type: CarburetorCustoms services and international tracking provided

  • Harley Davidson Carburetor & Manifold KEIHIN Dyna Shovel Head 27029-86B 0437

    And I Do Block Them For Life. If You Are Using A Cell Phone To Buy This Without Seeing Larger Pics, And The Condition Is Not As Good As You Had Expected. This Is Your Fault.
    Brand: Harley-Davidson
    $27.23 shipping
    Type: CarburetorCustoms services and international tracking provided

  • 2000 Kawasaki Kx500 Nice Keihin Carb Carburetor

    Removed From: 2000 Kawasaki KX500. This carburetor is in good condition and shows normal signs of wear. When that process is complete, our carburetors are beautiful and ready to bolt on and use. Many parts will fit other units as well but it is up to you to do the research in that respect.
    Top Rated Plus
    $27.00 shipping
    Brand: KawasakiType: Carburetor

  • 1997 CR250 CR 250 KEIHIN Carburetor Carb Fuel Twist Throttle Cable PJ28LAKJ

    Thanx for Looking ! Good Physical Condition.
    Brand: Honda
    Trending at $132.97
    Type: CarburetorCustoms services and international tracking provided

  • Suzuki Gs1200ss Keihin Carburetor Carbs

    <p>Keihin cvr32ss carbs. Need cleaning but in good shape.</p>
    Brand: Keihin
    $22.32 shipping
    Type: CarburetorCustoms services and international tracking provided

  • 2002 Suzuki RM85 RM85L Keihin Carburetor Carb Intake Throttle 13200-03B30

    This is a Good OEM Suzuki Carburetor. It is in good working condition. It has been disassembled for cleaning. It may need to be jetted for your application.
    Brand: Suzuki
    $27.13 shipping
    Type: CarburetorCustoms services and international tracking provided

  • 03 KAWASAKI KX85 CARB KEIHIN 01-13 OEM CARB CARBURETOR 15003-1617 KX100

    03 KAWASAKI KX85 CARB KEIHIN CARBUERATOR.
    Brand: Keihin
    $32.22 shipping
    Type: CarburetorCustoms services and international tracking provided

  • 07-08 2007 RM250 RM 250 KEIHIN Carburetor Carb Fuel Twist Throttle Cable PWK37FA

    Condition: Genuine OEM Keihin PWK37FA Carburetor including Cable and Twist Throttle. In GREAT working condition with no cracks breaks or repairs. Ready to install. 2007 Suzuki RM250.
    Brand: Suzuki
    $71.75 shipping
    Type: Carburetor

  • Replaced For Keihin Carburetor PWK38 PWK 38 38mm Airstriker Air Striker Carb 1x

    Keihin PWK Model, High Quality. For Super Performance Keihin PWK Power Jet Carburetor CARB Universal For Motorcycle, Scooters, Dirt Bike, ATV. Size: 38mm fit on 150cc to 350cc engine. 1 Carburetor.
    From China
    Was: Previous Price$32.16
    Brand: UnbrandedType: Carburetor
    Type: Carburetor
    Was: Previous Price$190.00
    Customs services and international tracking provided

  • 1997 95-97 RM250 38.5 MM PWK KEIHIN CARBURETOR CARB FUEL THROTTLE BODY INTAKE

    Keihin 38.5 mm PWK Carburetor will fit 1995-1997 RM250. This is a nice looking and great working carburetor. Throttle assembly needs new inner tube. Cable should be checked before installation. This is a good working item(s) that has been used and has plenty of life in it.
    Brand: Suzuki
    $55.40 shipping
    Type: Carburetor

  • 2006 Honda Crf250x Nice Refurbished Keihin Carb Carburetor

    Removed From: 2006 Honda CRF250X. This carburetor is in very good condition and shows normal signs of wear. When that process is complete, our carburetors are beautiful and ready to bolt on and use.
    Top Rated Plus
    $40.50 shipping
    Brand: HondaType: Carburetor

  • 1997-2007 Yamaha YZF600R Carburetor, carbs, gas and fuel carburetors CVK KEIHIN

    <p>1997-2007 Yamaha YZF 600 Carburetor, carbs, gas and fuel carburetors. Condition is Used.</p><p>Pulled from 2006 Yamaha yzf600r at 33,205 miles</p><p>Untested</p>
    Brand: Yamaha
    $20.56 shipping
    Type: CarburetorWarranty: No WarrantyCustoms services and international tracking provided

  • 1991 91 Kawasaki KX125 KX 125 Carb Carburetor Keihin PWK

    Here is a nice carburetor from a 1991 Kawasaki KX125. Carb is untested, but is clean & appears to be in very good condition.
    Brand: Keihin
    $26.81 shipping
    Type: CarburetorWarranty: No WarrantyCustoms services and international tracking provided

  • 1966 HONDA C65 OEM CARBURETOR KEIHIN

    From Canada
    or Best Offer
    Brand: Honda

  • Keihin PZ30 Carburetor + Gas Throttle Cable For 200cc 250cc Pit Bike ATV

    Other Areas/Countries.
    From China
    $6.00 shipping
    Brand: UnbrandedType: CarburetorWarranty: Unspecified Length

  • 03-04 2003 YZ450F OEM CR FLAT KEIHIN CARBURETOR THROTTLE BODY FUEL INJEC

    Carburetor with throttle assembly. A very good working carburetor. It has plenty of life left in it. Pictures explain it all.
    Type: Carburetor
    $59.15 shipping

  • 1984 Honda CR125 Keihin Carb 16100-KA3-741 Throttle Housing Cable CR 125 84

    1984 Honda CR125 Keihin Carb P/N 16100-KA3-741. Pulled from the strong running 1984 CR125 pictured.
    Brand: Honda
    $25.16 shipping
    Type: CarburetorCustoms services and international tracking provided

  • HARLEY DAVIDSON B83HUE26 B83H CARBURETOR, INTAKE AND AIR CLEANER,KEIHIN

    This was removed many years ago when a set of cams and carbs were upgrade on the bike.
    Brand: Harley-Davidson
    $63.70 shipping
    Type: Carburetor

  • 1988 Honda Cr500 Carburetor Carb Intake Fuel Cr 500 Keihin 88 250

    <p>This is a used carburetor removed from a 1988 Honda cr500. The carb is complete and in good condition. The slide moves as well as the choke. The throttle assembly is included in sale. The inside seems fairly clean with no broken parts. I have not heard this carb run so I’m assuming it will need cleaning/rebuilding before running. It is a used part so it will have its normal wear and tear, therefore sold as is.</p>
    Brand: Keihin
    $26.41 shipping
    Type: CarburetorWarranty: No WarrantyCustoms services and international tracking provided

  • 94-96 YAMAHA GENESIS YZF600R YZF 600 Carbs Carburetor OEM KEIHIN 34MM

    Location: CL-185 CARBS. These are quality used OEM parts unless otherwise noted. By definition, a used part is expected to have normal use scratches and marks. We will try our best to point out and show any abnormal points of interest in the picture.
    Top Rated Plus
    $18.81 shipping
    Brand: KeihinType: CarburetorWarranty: No WarrantyCustoms services and international tracking provided

  • 1997 HONDA CR 80 CARBURETOR KEIHIN CR80

    Removed from a running 1997 Honda CR80. Item has imperfections from being used. May fit other years and models. May need cleaning or rebuilt. Please ask questions if I have missed something.
    Brand: Keihin
    $16.35 shipping
    Type: CarburetorWarranty: No WarrantyCustoms services and international tracking provided

  • 1983 83 Honda CR250R CR 250 Carburetor Intake Carb Keihin 16100-KA4-711

    In good condition, will need to be rebuilt.
    Brand: Honda
    $28.76 shipping
    Type: CarburetorCustoms services and international tracking provided

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  • 2004 Suzuki RMZ250 Carburetor Keihin FCR 37mm 04 05 RMZ 250
    +$17.43 shipping
    Make Offer - 2004 Suzuki RMZ250 Carburetor Keihin FCR 37mm 04 05 RMZ 250
  • 74 Honda MT 125 used Carburetor Intake Fuel Genuine Keihin
    +$20.34 shipping
    Make Offer - 74 Honda MT 125 used Carburetor Intake Fuel Genuine Keihin
  • $85.00
    Make Offer - KEIHIN CR29 spigots, intake adapters
  • 1982 HONDA XR500R XR 500 MOTOR CARBURETOR CARB KEIHIN OEM
    +$27.83 shipping
    Make Offer - 1982 HONDA XR500R XR 500 MOTOR CARBURETOR CARB KEIHIN OEM
  • 1983 Honda Shadow 750 Vt750 Carbs Carburetors Keihin 7AA OEM
    +$25.53 shipping
    Make Offer - 1983 Honda Shadow 750 Vt750 Carbs Carburetors Keihin 7AA OEM
  • $199.00
    Make Offer - Suzuki Gs1200ss Keihin Carburetor Carbs
  • Harley Carburetor & Manifold Parts Lot / KEIHIN & MIKUNI
    +$34.50 shipping
    Make Offer - Harley Carburetor & Manifold Parts Lot / KEIHIN & MIKUNI
  • Honda CJ360 T CJ360T CJ 360 Carburetors Keihin 754A
    +$35.46 shipping
    Make Offer - Honda CJ360 T CJ360T CJ 360 Carburetors Keihin 754A
  • 1991 91 Kawasaki KX125 KX 125 Carb Carburetor Keihin PWK
    +$26.81 shipping
    Make Offer - 1991 91 Kawasaki KX125 KX 125 Carb Carburetor Keihin PWK
  • $71.40
  • 1988 Honda Cr500 Carburetor Carb Intake Fuel Cr 500 Keihin 88 250
    +$26.41 shipping
    Make Offer - 1988 Honda Cr500 Carburetor Carb Intake Fuel Cr 500 Keihin 88 250
  • 1983 83 Honda CR250R CR 250 Carburetor Intake Carb Keihin 16100-KA4-711
    +$28.76 shipping
    Make Offer - 1983 83 Honda CR250R CR 250 Carburetor Intake Carb Keihin 16100-KA4-711
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