Keihin 41mm FCR Kit for KTM 640 LC4 Adventure

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Product Overview

What's in the kit:

  • Keihin FCR 41 mm Carburetor 
  • Special adapters to mate the FCR body to the inlet manifold and air box
  • Includes New Motion Pro Push Pull throttle cables
  • New Push-pull throttle grip 
  • Keihin Guide and Instructions

Product Features:

  • Outstanding upgrade for the engine
  • Everything needed for a pro install is included
  • Mates perfectly to the stock airbox
  • Restart (due to slow changeover to reserve) is much quicker than with the stock Mikuni

Product Benefits:

  • Superb... I repeat, Superb throttle action
  • Increase in HP and torque and we mean Increase 
  • Rev up through the RPM is much quicker
  • Performance increase is substantial
  • Transforms the KTM 640 into a more powerful bike
  • The sound during acceleration is just addictive


  • Made in Japan


These guidelines should be followed when installing carburetors and other Keihin products

  • To avoid injury, carburetors should be installed when the engine is cold
  • Read the owners manual for your vehicle before installing any Keihin product to prevent any damage to the vehicle due to improper installation.
  • Gasoline is extremely flammable and can be explosive under certain conditions. Installations should be done in a well-ventilated area.
  • Installation of products in this catalog should be done by an experienced mechanic or service technician.
  • 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.

These Keihin flatslides are the world standard in high-performance carburetion!

If you love your bike this is the highest performance engine upgrade you can make. 



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  • 5
    Keihin 41mm FCR Kit for KTM 640 LC4 Adventure

    Posted by Wayneo on Feb 20th 2023

    Very happy with the kit, and especially the customer service regarding answering installation questions. The bike has noticeably more power, and throttle response was improved significantly making lofting the front wheel much easier. Fuel economy is equivalent, if not slightly better than the standard bst40 so far. My test loop was a mix of highway, gravel, two track and single track hillclimbs which gave an economy of 6.0l/100km. A little better than my last ride with the BST40. Supplied jetting is good for my '05 with full akra system (no baffle yet) and no snorkel. I have not had a chance to see if it needs tweaking. The kit was not able to work with the factory emissions equipment, and I bought some 4mm vacuum line to plumb the vents in addition to the buying the kit. The kit came with new cables and throttle tube, so swapping grips is required as the supplied motionpro cables ends are too thick to work with the factory throttle arrangement. The standard airbox to carb boot did work with the carb, but was tight enough to require removing the top two subframe bolts and mid pipe bolt to allow carb install. All equipment was new and supplied with a Keihin manual. The cable mount on the carb is the opposite side to the BST, requiring some slight changes to the wiring loom location, but easily changed.

  • 5
    The carb is the carb the bike should have come with

    Posted by Timber Pilot on Feb 8th 2023

    Bike is noticeably crisper with increased throttle response. More top end as well. Bike seems to run cooler. Bike seems to vibrate less. It's definitely a wake up call for the bike.