GY6 171cc / 172cc Scooter Big Bore Kits (FITS QMJ157)

If you are looking for the best bang for your buck in performance, CLICK HERE! This Rolling Wrench kit is the ticket! We have spent years testing and selling other kits. Some things we liked and others we didn't. We pieced this kit together with the best of the best materials (rings, gaskets, springs, and metals). This 12:1 compression ratio 171cc kit (or as some call it 172cc) is a no case boring, big bore kit, unlike some others on the market. It's the largest big bore kit you can go on the GY6 A motor (Chinese GY6 QMJ157).Our 61mm kit is a drop in kit. Others on the market are not, and will require engine case boring. Like they say, “there is no replacement for displacement“. Another cool thing is the piston ring end gaps have been set and installed into the cylinder. This eliminates a ton of work and liability on your end. Easy peezy! For the money, this kit flat out rocks! We even have an install video! We would recommend adding a performance cam shaft and big valve head to the k