Motorcycle Repair: Engine swap capability., honda qa 50, lifan motors

Question
Hi I am interested in putting a new engine in my 1971 QA50 K0 50cc as the Keihin Q4B carb is shot. I have heard of guys throwing Lifen 125cc's in their Honda's. Do you know if I would need to cut and weld the frame to make it the motor fit? Here it is:

http://www.pccmotor.com/semi-auto-lifan-125cc-auto-engine-xr50-crf50-crf70-w1255


Thank you in advanced!

Answer
Hi Adam,

The Lifan motors do not fit directly into a QA50.
It can be done but requires mocking up the engine
and taking measurements and then making some
motor mounts to fit and hold the engine securely.

The front wheel clearance can be an issue on using
larger engines.

The Lifan engine overstresses the small frame a bit
and the speed would be dangerous on such small wheels.

If you go ahead then be very careful that everything is
made strong enough to handle the bigger engines torque.
Test the bike on some soft ground to get used to the power.

I know it can be fun but getting a bigger bike is usually
a better idea in the long run. The handling is much
better on larger wheeled bikes.

Here is a webpage that outlines some of the frame
modifications required for the Lifan engine to fit:
http://www.thumpertalk.com/topic/713801-honda-qa-50-engine-compatability/

Good luck on your projects!

Wayne S
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