Please select make, model and yearBig Bore Kits
High quality off road big bore kits.
Brad in UT
Application '05 Yamaha WR 250F w/pro-motto-billet quiet insert in stock exhaust. My goal was to give me more power for the sand and straight sections in Desert racing. Result more grunt down low and big improvement riding a gear high through whoops. Overall my top speed seemed to suffer. Conclusion: For Desert Racing not worth the money, for Woods riding totally worth it. Installation excellent. Durability incredible! Installed 03/2007 prior to a 10-race Desert Series. 2008/09 and 2010 averaged 60 hours/year ride time and competed in 3 additional Desert races. Today 11/2010 original Athena piston going strong.Read All Reviews
Mike in ID
I WAS A LITTLE SCEPTICAL ABOUT THIS PRODUCT. HOW COULD MOVING THE MOTOR 2.5mm MAKE THAT MUCH DIFFERENCE? AFTER READING SEVERAL REVIEWS ON LINE AND IN MAGAZINES I DECIDED TO GIVE IT A TRY. I COMBINED THIS PRODUCT WITH A MAXISS EN FRONT TIRE AND WOW WHAT A DIFFERENCE. I AM 250 lbs AND DIDN'T HAVE NEAR THE TROUBLE WITH THE "DARTING" THAT ALOT OF OTHER YZ OWNERS COMPLAIN ABOUT. THIS TOOK ME FROM REALLY LIKING MY BIKE TO LOVING IT. DON'T HESITATE. JUST BUY IT. INSTALL WAS FAIRLY EASY USING THE VIDEO ON THE DRD WEBSITE.Read All Reviews