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CRF/XR50 18mm Big Carb Kit


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CRF/XR50 18mm Big Carb Kit
QTY    $
Any additional options and/or replacement parts will be available at the bottom of this page

CRF/XR50 18mm Big Carb Kit

Perfect add-on for our Big Bore kits and exhaust systems. Increase power throughout the RPM range utilizing 18mm carburetor. Includes all required hardware for easy installation right down to a jet assortment for fine tuning..

These carb kit will also work great on a 1988-1999 Honda Z50R using 7/8" handlebars.

Choose your kit.
420-HXR-5002 (shown in photo) includes 2 intake manifolds. One for use with stock XR/CRF50 heads and a second that is for use with aftermarket big valve heads or the stock XR/CRF70 head.
420-HXR-5003 includes just the manifold for use with stock XR/CRF50 heads.
420-HXR-5004 includes just the manifold for use with aftermarket big valve heads or the stock XR/CRF70 head.

  • 18mm Carb
  • Special manifold sized for the CRF/XR50 head
  • Special manifold sized for the big valve heads (XR70 and aftermarket)
  • Includes gaskets and bolts
  • Includes throttle and cable
  • Includes 5 main jets and 3 pilot jets

Application Note: This 18mm Carb Kit is not recommended for use on stock displacement CRF50's. Recommended for 82cc or larger displacement motors.

Note: The throttle in this kit is for standard 7/8" diameter handlebars. The stock Honda XR/CRF50 uses 3/4" diameter handlebars. You must use a handlebar kit that changes to 7/8" diameter handlebars to use this throttle. BBR does not make or sell any throttles for 3/4" handlebars

Note #2: This kit does not include an air filter and will not work with the OEM Honda CRF/XR50 air filter. See the UNI filter we recommend (BBR part number 430-HXR-5002) below in the Optional Parts section.

BBR General Jetting Guidelines Chart

Part NumberImageDescriptionPrice 
420-HXR-5002420-HXR-5002Carb Kit - BBR 18mm Stock/Big Valve Heads / XR/CRF50,
420-HXR-5003420-HXR-5003Carb Kit - BBR 18mm Stock Heads / XR/CRF50,
420-HXR-5004420-HXR-5004Carb Kit - BBR 18mm Big Valve Heads / XR/CRF50/70,

Replacement Parts

Part NumberImageDescriptionPrice 
421-BBR-2001421-BBR-2001Carburetor Only - 18mm (80m/35p)
421-KEH-3002421-KEH-3002Jet Kit - 18mm Carb, PC18/20 (33,35,38,40,42,70,75,80,85,90,95,100)
421-KEH-6033421-KEH-6033Jet - Keihin 33 PC18/20, XR/CRF80
421-KEH-6035421-KEH-6035Jet - Keihin 35 PC18/20, XR/CRF80
421-KEH-6038421-KEH-6038Jet - Keihin 38 PC18/20, XR/CRF80
421-KEH-6040421-KEH-6040Jet - Keihin 40 PC18/20, XR/CRF80
421-KEH-6042421-KEH-6042Jet - Keihin 42PC18/20, XR/CRF80
421-KEH-9001421-KEH-9001Carburetor Repair Kit - 18mm
422-HXR-5002422-HXR-5002Intake Manifold - XR/CRF50-70/PC18/Big Valve
422-HXR-5003422-HXR-5003Intake Manifold - XR/CRF50/PC18/Stock
512-BBR-1001512-BBR-1001Throttle Cable - BBR 18mm/26mm Carb Kit / XR/CRF50 / KLX/DRZ110 / Bar Kit - CRF110F /
512-BBR-2001512-BBR-2001Throttle Assembly - BBR Carb Kits / Brake

Optional Parts

Part NumberImageDescriptionPrice 
430-HXR-5002430-HXR-5002Air Filter - UNI, 1 1/4"(32mm) X 4", Straight / 18mm Carb / XR/CRF70 Stock
500-BBR-1001500-BBR-1001Grips - BBR 'CR'
Prop 65 Warning