2019 GY6B 125 Cylinder Kit

[125 Mech]

Hi all working on a 2019 GY6B injected that was trashed by the low life that stole it,anyway it needs a cylinder kit I bought one but the alignment of the cam chain tunnel is off by about 3mm I am coming up blank engine type is 152QMI 52mm bore.

[Nobby the Bastard]

[stevo123]

If it is for cam chain is the 3mm critical - will the chain interfere for example. If not I can't see a huge issue. As Nobby said send it back or call the seller and discuss first probably best options.

[125 Mech]

The problem is that there so many types of GY6 engines but I bought the cylinder kit as a post 2011 125cc but the gasket and obviousely the cylinder has a slightly different spacing

[Robby]

So buy one that fits.

The one thing that owners of Chinese 125 owners get to be smug about is how interchangeable the parts are. For the rest of us, you need to get the exact part to fit your bike, down to quite a slim range of model years as well. If you're lucky there might be an aftermarket combination that will work, but that is rare for something as major as a cylinder.

Chinese bikes, you just need to have one that matches your engine code. I'm assuming here you bought the cheapest, and it doesn't quite match. Find a decent seller who can provide one that fits.

Also worth asking - are you sure it need a cylinder kit? Replacing the cylinder seems to happen surprisingly often on Chinese 125s, even more so than when we used to rebuild our 2 strokes. The thing that will usually kill a piston and score a cylinder is running out of oil - in which case the rest of the engine is probably scrap as well.

[125 Mech]

This bike is 7 months old 500 miles on it. It was stolen and ridden flat out till it seized piston melted cylnder. Hopefully CMPO have replied to my request and have on order they say the correct kit

[Nobby the Bastard]

[Robby]

I suppose it might be possible, if you had the bike sat stationary at the redline for half an hour. It would be an interesting science experiment. If the bike was moving, such as being ragged around a field until it ran out of fuel, it wouldn't break like that. It's a tough engine design, intended for extended heavy use in developing countries.

Still, chances are that other things are fucked and I would be replacing the engine. If it got hot enough to melt a piston and didn't have massive air leak, then the oil would have been thin enough to not do much lubrication in the bottom end.

At the very least get the bottom end checked over by someone who knows what they are doing.

[125 Mech]

Ive been working on bikes for 30 years, also why do they sell GY6 cylinder & piston kits by the thousands every month look at eBay supliers 200 in stock sold 3000. China made 20 million by 2006 by 2012 it was making 24 million a year

[Nobby the Bastard]