weird issue with 110cc atv piston size at 47mm instead of 52mm

[pcbisnice]

Hi everyone. I have 2 roketa 110cc atvs. both automatics. Both cylinders are stamped 107cc on them. I put a new piston and cylinder into one earlier this year without issues. I am currently trying to do the same with the other but the sizes are off. I bought the exact same kit, 52.4mm. It does not fit. I measured the old piston and it's 47mm across. The 110cc engines should have a 52mm piston, correct? The engine is stamped 107cc... but it's got a piston from something smaller? My research shows the 47mm piston was in the 70cc and some 90cc. How do i have one on a 110cc? It doesn't make any sense at all. The new sleeve won't fit the block, it's too big to slide down in. I have googled a ton, but it seems I am the only one to have this issue. I am hoping I just missed something? Have any of you ever seen a 110cc chinese engine with a 47mm piston? is there anything else i need to check?

[buzz]

Its probaly onlt a 90cc engine

[shad88]

I had the same thing happen a while back. Head was stamped 107, but ended up being a 70cc. I asked about it on another site and was told it's just poor quality control when they were stamping.

[krat]

Welcome to the real world, where a China bike 250 is actually a 229cc, 200cc scooters are actually 165cc, and your Honda 300 is a 279cc.

It is not a "quality control" issue. Even the Jap and most of the European builders do the same.