I like the 3MA concept and I like 125's, making a combination would be perfect.
Have worked out serval ideas, but all the planes needs lots off work.
Thought about cutting one cylinder off a 3MA engine, and modified the crank and cases.
But this will make a very big 125 engine, with no real potential.
Using the 4DL engine, mound a cylinder that has the inlet on the cylinder it self rotate it so carb is at frond and exhaust at the back
Problem is the water channel, witch will need a lot off changing.
Using a other engine, that can be changed to a 3Ma setup, as the stock 4DL engine is original a moto minarelli so perhaps parts off different engines will fit.
What frame to use would be simple as the 4DL frame is very close to a 3MA frame.
In fact using a 4DL rolling chassis would be perfect.