CG125 Engine conversion to 250 Help
 

Hi

So I have been looking at buying a 230cc - 250cc engine that will bolt into my CG125T frame as a fun project. I was originally looking at an overbore kit but looking at research its a one way ticket to a melted engine.

Looking at multiple sources I found a couple of brands to look that being Loncin, Shineray and Zongshen. They all appear to have 250cc engines that follow the same design as the CG125 engine but I am uncertain if the dimensions line up. I'm aiming to have as simple time as possible changing over the engine so no mounting brackets/aligning the chain sprockets.

Basically what I'm trying to find is just an engine that will bolt directly in, hopefully has a bit of power behind it (well whatever a 250 can deliver) but also reliable, price isn't too much of an issue.

Any help is welcome.

As long as it isn't counterbalanced, any of the 'normal' 250s (that is to say not a true 250), even the OHC models, should bolt right in. You might need to make a different top mount, but that should be really easy.

Why do I not want it to be counterbalanced? I do actually have a spare Honda CB250 nighthawk engine that might be able to fit in.

I'm only taking about Chinese made motors. I have no clue about Nighthawk fitment (personally, I hate those motors, too much vibration and too little power for it to be worth it, also not worth the extra weight, to me). You don't want a counterbalanced motor because it protrudes more in the front, meaning it might either hit the lower downtube, or require you to fab up a new front mount. From what you were saying, I assumed you're looking for the easiest bolt-in possible, so I was giving you the option with the least amount of fabrication.

A cg250 will fit into a cg125 without issue. Assuming the lower crankcase profile is the same it should bolt up using the same front engine bracket.

FYI I have a cg300 engine, in a CG125 frame.

https://i.imgur.com/OpOmo9c.jpg