Does BBR make a big-bore kit for the CRF/XR50?
Yes. BBR sells several different big bore kits ranging from 82cc to the wild dual overhead cam 124cc kit. For backyard riding we recommend the 82-88cc kits. These kits are our own aluminum cylinder with iron liner, 82-88cc piston, rings, pin, clips, gaskets, and a high performance camshaft. No exchanges are required. This piston is 9.75:1 compression (with the CRF/XR50 head) and will run great on pump gas. We prefer this setup over the bigger bore kits as it lasts longer, is easier on the oil, and doesn’t overheat as easily. This due to the thicker cylinder sleeve. This kit is the quickest way to double the horsepower on the CRF/XR50 without reducing reliability. We also have an 88cc kit for use with the stock head, an 88cc kit with a big valve head, and we have high end engine kits available. If you’re going big, trying to make money, or just need to have the coolest bike in your neighborhood garage, the Kitaco 124SE kit or Daytona 4-valve kit is the way to go. Engine kits for the XR/
