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Keihin Carburetors
Read the carburetor FAQ
Carburetors are not returnable
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FCR-MX accelerator pump spring
Direct replacement for the wimpy stock spring. Gives a much more consistent accelerator pump squirt. Eliminates the need for the 'O-ring mod', wire or zip-ties on the pump arm. Fits all Keihin FCR-MX carbs except '07-'08 CRF250/450.
Merge Racing Fuel Mixture Screw
Top quality brass screw with molded knob for easy adjustments. Fits all FCR-MX carburetors only.
Boyesen Quickshot 3 Accelerator Cover

This cover acts as an 'adjustable leak jet' to fine tune the accelerator pump squirt.

Eliminates "4-stroke bog" when used with correct jetting. Allows the use of correct carburetor settings to optimize performance, starting and reliability. Improved low-end performance with much better throttle response. Investment cast and finished to precise tolerances with internal high volume vertical check valve. Fits all motorcycles and ATVs using a Keihin FCR carb. Easy installation instructions (including online video) and template.

FCR Mod Kit
Just an updated version of our Mod Kit. We now include the Boyesen Quickshot 3 Accelerator Pump Cover (see above), Merge Extended Fuel Mixture Screw and the FCR-MX Accelerator Pump Spring all in one kit. And at a lower price than before.
R&D Flex Jet NEW!
R&D introduces "Flex-Jet", a simple, effective flexible shaft design. Quick adjustments are now within easy reach. Besides easy access, another benefit is the Flex-Jet's ability to hold its setting. Loose fuel screws are now a thing of the past. Kit includes: Flex-Jet (Remote Fuel Screw), bracket, screw, spring, washer, o-ring, instructions 59-1002
Sunline FCR carburetor calibrated fuel mixture screw
Fits OEM FCR Honda, Yamaha, KTM, Suzuki, Kawasaki carburetors.
FCR carburetor 'Dial it in' Combo
Boyesen QuickShot 3 plus Sunline mixture screw
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