140cc 125cc Franken build. Advice wanted.

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Nov 5, 2019
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Hello there. We are working on my buddies bike motor and are attempting to build something different
He has a gio 140cc barrel and piston we were going to widen the case a bit so the sleeve will drop down. In to the bottom end. The bottom end is a lifan 125cc with the 14mm wrist pin. Piston fits on no issue.
And we want to use the valve head from the 125 as well if possible. Or use the 140 if need be.

The strokes are obviously different and we are willing to swap cranks if need be. Just mainly need to use the 125 bottom end as the 140 is done.

Curious if the timing will work using the 125cc. We were thinking if we used the 125 valve head on the 125 bottom end with the 125 stroke. This would be the simplest. Some mods do have to be made as the timing chain slots dont match perfectly but is very minor.
Unless the head bolt spacing is different only by millimeters it will fit on no problem.

What about electronics.
So on and so forth. Assuming we use the 125 crank the stroke will create a large gap making the bike low on power. The piston is domed but is there a custom piston available? Can always call weisco and have them custom make one. Or shave the barrel down.

Any thoughts would be appreciated if you need any info just let me know.
Flywheels. Stators, rectifiers. What should be used where. Does the flywheel need swapped.

Most of you would buy a top end. We use what we have and can find and build with out buying a bunch of stuff if not needed.
Thank you all. We are not new to custom work. His mini bike will do over 80km/h with ease with no aftermarket parts. Just need some expert opinions on something that likely hasnt been done.

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