Review on Trkimal 100cc Big Bore Kit for 64mm Valve - 139QMB Moped Scooter Engine - 50mm Bore Upgrade Set with GY6 Cylinder Rebuild Kits, 6pin Racing CDI Ignition Coil, Performance Spark Plug, and Clutch Spring by Gregory Shin

Because it's essentially a standard upgrade, it includes seals that you won't even use in most cases, depending on your application. It's a nice touch as all too often many of these types of kits don't work. There's nothing more frustrating than completing a project halfway or better, only to find that gaskets, certain screws, nuts or components are missing. You then have to put your project on hold and wait for the part you want to start with. Available for 64mm or 69mm valves. Let me clear up the confusion you need to get out of. Because this set includes everything you need to get the job done, you can choose whatever you want. If you plan to reuse your own rocker arms, you need to know how long your valves are. If you are using all the parts provided then if your previous build was 64mm and you ordered a 69mm kit then you don't have to worry. The only reason to really worry about what valve length you should get with this kit is if you plan on porting and polishing the intake valve. and head exhaust. Let's start with the wall thickness being thin at 64mm. If you try to port a 64mm head you will quickly run out of material and blow the wall straight into the valvetrain compartment. Check out the difference between 64mm and 69mm on 49ccscoot com, he explains the difference in great detail. .The only thing that could make this kit more complete would be if it included a larger carburetor to accommodate the larger displacement you are installing. My suggestion: buy a good carburetor for your GY6 150cc instead of messing around with injectors to get your existing carburetor working.