Please select make, model and yearBig Bore Kits
High quality off road big bore kits.
Matthew in VA
Put this in my 2007 RMZ250 along with Intake and Exhaust Hotcams. It feels like I bought a new bike. With the big-bore I have the low end and midrange to blow up any berm. The Hotcams give me the top end that doesn't fall off either like some big-bores can. This is all with the stock pipe and silencer with a Pro-Moto Billet Endo's spark arrestor to quiet it down so I am <96db for Hare Scrambles racing. Don't waste money on a pipe get the big bore.Read All Reviews
Jacob in TN
Very dissappointed in the knowledge of the RM sales team. They told me that all I would have to do (to my 2004 400ex) was press out the old sleeve and press the new one in, however that was not the case. The machine shop had to press out the old one, bore and counter bore the cylinder in order to press the new sleeve in, then after getting the cylinder back I went to put it all together just to find out that the sleeve had to be bored to the piston also. Wasn't very costly to have done ( about $120) but would've been nice to have known all this from the start. Wisecos 440 big bore kit is the bomb tho, along with hot cams stage 2 cam and a dyno jet jet kit my quad is wicked fast.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