How to install a bigger crankshaft

[blueboy5000]

Well if you're not familar with what a 'woodruff key' is, you should probably not use your 150cc engine as a learning process! (it's a little rectangle of hardened steel that sits in a groove on a crankshaft)

A 63mm cylinder requires BORING of the cylinder, which requires HONING of the cylinder as well (unless you purchase the "jug" pre-bored and honed) milling of the jug may be required to fit properly, as well as a MINIMUM of 2 base-gaskets.

This is NOT a first-time try and see experience, crank and BBK is the most difficult mods possible to a gy6. Removing the old crank bearings requires use of a torch. Reinstalling the crank bearings requires FULL diss-assembly of the ENGINE CASE and full cleaning, as you will have to heat the block in an OVEN and freeze the new bearings in a FREEZER or DRY ICE bucket to make them fit. I have found no way to accomplish this without use of heat and cold.

Again I state this is a VERY DIFFICULT mod, not for the inexperienced.

Your 232 engine will require a much-modified carb, bigger cam(s) and would greatly benefit from improved CVT and OIL COOLER as well. A 232cc runs much hotter than the stock gy6 157.

[James2132]

Thanks. Yes rebuilding gy6 engines can be difficult but it's something every scooter owner will have to do eventually anyway, replacing top end crankshaft etc.... Unless they pay someone else to do it, which is too expensive for me. So I might as well learn now. I have about 2800 miles so far. From what I have heard that's about half the life of a gy6 engine. 6000-7000 miles. I ride wot a lot, really don't have much choice because it's hard keeping up with traffic where I am.