Review on Glixal ATMT1-005 High Performance GY6 50cc to 60cc 44mm Big Bore Cylinder Kit with Piston for 139QMB 139QMA Scooter Moped ATV: Boost Your Ride's Power! by Alex Winnick

Excellent fit and finish, well honed bore finish and all parts are very good quality as far as the eye can see. The only (minor and somewhat expected) issue was a slightly "tight" end gap on the top compression ring. a minute with a small file did it (about 0.001 inch removed). I'd rather have the new gaps on the tight side than the loose side, ie you can take some off but not put back on! Everything went without problems, from the start it started and worked perfectly, with no leaks (good seal). and 80 miles total so far, it hasn't used a drop of oil and the oil stays very clean/slightly amber - a sign of a good, fast o-ring. Top speed (otherwise a stock 139QMB) is up from 60km/h on the original 49cc to around 42-43km/h (actual) and has noticeably better mid-range traction upwind/uphill. My target constant cruising speed is 30-32 km/h (actual). to take 2/3 of the gas - now takes about 1/3 of the gas. So far very happy with (fingers crossed) these excellent results. Keep it up Glixal! good material.