BBR 88cc Flat Top Piston Bore Kit
BBR 88cc Flat Top Piston Bore Kit  
411-HXR-5400(A), Bore Kit - 88cc FTP W/Cam, XR/CRF50, 00-Present
411-HXR-5210(A), Gasket Kit - 88cc S/P-FTP Kit / XR/CRF50/70
411-HXR-5212(A), Ring Set - 88cc/106cc S/P-FTP Kit / XR/CRF50/70
411-HXR-5250(A), Cylinder - BBR Aluminum, 52mm / XR/CRF50
411-HXR-5411(A), Piston Kit - 88cc FTP Bore Kit / XR/CRF50
422-HXR-5003(A), Intake Manifold - XR/CRF50/PC18/Stock Head
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Convert your CRF/XR50 to an 88cc screamer with this complete kit. Everything is included to upgrade the performance of you mini-bike. This kit uses your stock CRF/XR50 cylinder head.  
    • Aluminum BBR cylinder.
• Special 52mm piston specially designed to work with your stock cylinder head's combustion chamber.
• BBR special grind camshaft take full advantage of the large piston for great performance.
• Special BBR tapered aluminum intake manifold adapts the large carb to the stock intake port size.
• 18mm carb includes extra main and pilot jets for easy tuning
• Also includes CR style throttle, cable, air filter and top end gasket kit.
• Installation available for $200 (plus shipping)
  Installation Note 1: Throttle unit included with kit will only work with 7/8" handlebars and will not mount to stock XR/CRF50 handlebars. Stock handlebars are 3/4".

Installation Note 2: This kit will not work with the Honda XR/CRF70 or other big port cylinder heads. It is designed for the tiny combustion chamber of the OEM Honda XR/CRF50 cylinder head. The flat top piston dome will result in an extremely low compression ratio when combine with the XR/CRF70 type cylinder head. The result is a motor that makes less horsepower than stock. BBR Does not currently make a big bore kit for the XR/CRF70.

BBR General Jetting Guidelines Chart
  Installation Instructions:  411-HXR-5400.pdf  

Part Number Application Price  
411-HXR-5400Bore Kit - 88cc FTP W/Cam, XR/CRF50, 00-Present369.95Please Call for Inventory Status on this Item
Replacement Parts:
411-HXR-5210Gasket Kit - 88cc S/P-FTP Kit / XR/CRF50/7019.95buy
411-HXR-5212Ring Set - 88cc/106cc S/P-FTP Kit / XR/CRF50/7032.00buy
411-HXR-5250Cylinder - BBR Aluminum, 52mm / XR/CRF50155.00Please Call for Inventory Status on this Item
411-HXR-5411Piston Kit - 88cc FTP Bore Kit / XR/CRF5098.00Please Call for Inventory Status on this Item
421-BBR-2001Carburetor Only - 18mm (80m/35p)95.00Please Call for Inventory Status on this Item
422-HXR-5003Intake Manifold - XR/CRF50/PC18/Stock Head42.95buy
512-BBR-1001Throttle Cable - BBR 18mm/26mm Carb Kit / XR/CRF50 / KLX/DRZ110 / Bar Kit - CRF110F / DRZ7024.00buy
512-BBR-2001Throttle Assembly - BBR Carb Kits / Brake Kits22.95Please Call for Inventory Status on this Item
Optional Parts:
205-HXR-5032Exhaust System - D2 Big Bore, Silver / XR/CRF50, 00-Present279.95Please Call for Inventory Status on this Item
385-HXR-5015Sprocket - Front, 15T / XR/CRF50, 00-Present16.95buy
405-HXR-5011Cam Cover - Billet, Black / XR/CRF50, 00-Present49.95buy
410-HXR-5005Clutch Springs - HD / XR/CRF50, 00-Present26.95Please Call for Inventory Status on this Item
411-HXR-5255Oil Pump - BBR High Flow W/Gasket / XR/CRF5049.95buy
430-HXR-5002Air Filter - UNI, 1 1/4"(32mm) X 4", Straight / 18mm Carb / XR/CRF70 Stock Carb18.95buy
451-HXR-5001Rev Box - Honda / XR/CRF50/70/80/10069.95Please Call for Inventory Status on this Item