• 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 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.