3MA cylinder on 4DL engine

TZR125 4DL Specials

A new project/idea has started.
I'm still 3MA minded, why not use a 3MA cylinder on a 4DL engine it has the same bore/stroke so way not.
It will be a great start with some nice potential.
It also needs a lot off work....

Because I'm a amateur, I use the gasket to locate the hole's I need drill

Clamp it on the milling machine

First hole drilling

Another one

Almost there

Having the same height
4DL vs 3MA

The stock porting has some potential

A single head from a 3MA SP will do the job

After cleaning it with a dremel, its fits nicely

First impression is good, but still a lot off work needs to be done

Drilling the holes isn't the hardest work, making it all fit will be the challenge.
Flow will be the main target

Changed a base gasket to the new transverse dimensions

The gasket show how much needs to be taken off.
As you can see it needs work

In big lines its not that bad, the direction is good

A typical Yamaha problem is the blocking off the C port.
Now it has a little bid more space du to the design off the 3MA cylinder