Just Another Puch E50 Dio Polini (Part 1: Case Matching)

(** NOTE: I started this project while I was in Japan and finishing it up in Hawaii. Hence the changes in scenery, geographical references, and available tools. If you were wondering **)

The moped I brought up to Japan came with an E50 Polini set up on it.  It was the first E50 I put together since I got into the Puch game over 15 years ago.  It ran pretty well with the basic match porting, stock 3 shoe clutch, stock points, Rito crank, 15mm Bing, 28mm header pipe, Magnum gutted exhaust, and 15x40 gearing.  It was probably going around at least 45mph.  It felt very safe and reliable.  But right after arriving to Japan, I wrenched it off and imported one of my ZA50s.  What can I say, I'm a ZA50 guy through and through.

Since I had the E50 lying around, I wanted to see if I can build this E50 to its maximum potential.  I already had the Polini kit so I decided to try my hand at building a Dio Polini set up.  I know its been done before with lots of information out there (i.e Magnum Dash).  But I feel I might be able to add something into the mix.



The before pictures:

PART 1:  CASE MATCHING

There are an abundant amount of case matching tips and tricks out on the net.  One of the most useful videos is by 1977 Mopeds.  I tried to incorporate some of those techniques in my match port work.  I used a Dremel with a flex shaft attachment and basic carbide and sanding bits. I always finish any port work by hand with mini files and sandpaper.

1)  Got some 1x300mm aluminum pipe from Unidy hardware store.  Cut them to size and press (more like pound) them in:

Complete!!

2)  Bolt on cylinder to both halves and mark up to see where you need to match.

3) Begin matching transfer ports.  Repeat Step #2 as required.  Always double check your progress to make sure you don't over port.  Take your time!!  It's easier to take off material than add on.  But if you do need to add material, epoxy or JB Weld does the trick.  Don't forget to port out the intake boost ports.

Top half in progress...

Bottom half in progress...

I "polished" the transfer ports and crankcase using 80 to 120 grit sandpaper.  "Polished" does not mean a mirror like finish.  Actually, a degree of roughness is required for these surfaces (see complete theory here).  Some people media blast the ports and crankcase to provide this uniformity.  It's an ongoing debate whether or not polishing adds any benefit versus leaving the surfaces "factory".  I figured I do this extra step since I'm trying to go all out.  I also ran my 80 grit sanding bit in the transfer ports of the cylinder to match the motor's surface roughness.

Results:

Top and bottom cases

For Polini Use Only

Transfer port.  I didn't go too big.

Transfer port.  Not to deep.

Crankcase roughened

In PART 2:  INTAKE AND EXHAUST MATCHING, I'll show mounting the Dio intake manifold to the cylinder and exhaust header to the cylinder.

Happy Tuning!!!