Category Archives: Chinese CG250 Engine

Exhaust on and wiring started

Got the exhaust fitted, surprisingly without too much modification. I made a battery box too.
Handlebar switches on, all cables installed and working. Speedo fitted. Chain and sprockets fitted, with new sprocket cover that arrived from China this week. I found a new chain guard in my hoard. Rear brake installed. Started mounting the new wiring harness, voltage regulator, CDI and starter solenoid. I’ve ordered 350mm rear shocks (stock are 300mm) and a shorty rear mudguard and small tail light. Hopefully that will alleviate the fat rear wheel clearance issues.

Next is the dreaded headlight spaghetti.

It’s a Roller and the engine is in.

CG250 Bitza build made good progress today. Got the tires on, wheels mounted, engine in. Some issues with front mudguard clearance, none, won’t go on, and I suspect modification of the rear mudguard will be required or some longer shocks. Tire is too wide to fit in the rear mudguard. Might buy one of them shorty AliExpress ones. Not sure about the inlet manifold angle either, carb isn’t anywhere near to being level. I think it looks ok so far though.

CG250 internals to CG125 cases is a fail

In the end I realised that the crankshaft taper on the CG250 crankshaft is different to the crankshaft taper on the old 6v flywheel crankshaft. The CG250 CDI engine appears to have a longer crankshaft on the flywheel side. I don’t want to machine the crankshaft on the CG250 engine, so that’s it, I’ve given up and re-assembled to CG250 engine to use as is.

CG250 engine project begins in earnest

I bought a 167FMM CG250 (233cc) Chinese copy engine. I’d like to use it in my recently completed silver CG125 but as the old CG125 is 6v with points ignition and the CG250 is 12v with electronic ignition I don’t much fancy changing the wiring harness and all the light bulbs. So I have been investigating swapping the crankshaft and cylinder, piston etc to some spare CG125 crankcases I have. The first issue is the crankcase cylinder opening size isn’t big enough to accept the larger cylinder liner, so today I set about boring the crankcases to accept the bigger liner.