Puch E-50 Polini, et cet observations

Just finished putting a Polini 64cc Kit with Technigas Next exhaust and Bing 15mm Carb on an old Penny's Pinto. (Thanks Steve's Moped and Bicycle World and Treats HQ on Ebay)

Here are a few observations, though this is probably old hat to a lot of people...

1. I didn't radius the crankcase, so I am missing out on a lot of induction volume, but it didn't seem too difficult to do with a Dremel tool or similar.

2. The instructions for the Polini kit are not great. Just FYI, the rectangular port in the piston is the top (12:00 position for the piston) with the kit.

3. The piston is a single ring piston and the ring gap goes at 12:00 too. The pin around which the gap goes in the piston is very subtle, but its there. So be aware that the ring gap must be straight up when assembling the engine.

5. The 15mm Bing requires the little "spigot" on top where the cable threads in and the banjo fuel line fitting from the original to work. Its a good idea to have new washers for the banjo fitting on hand if you intend to go with a Bing carb.

6. The 15mm Bing comes with an 82 Jet which works ok with the Technigas and Polini (with stock airbox) but does have a little flat spot off idle. The Polini instructions recommend a 70 size jet. But from experience, this is too small. The solution is somewhere in between.

7. The Technigas-Next exhaust will not allow you to pedal the moped. There is a clearance issue between the pipe and pedal arm.

I am sure I am missing stuff, but feel free to add!

Re: Puch E-50 Polini, et cet observations

You got most of it, however...I'll add.

1) Radius the crank case. If you drop the engine and split the case you can actually do an excellent job. I did a JV job with the engine still on and a rag stuffed behind the crank.

2) Junk the 82 jet. I just upjetted to a 90.....and it now runs like an ANIMAL. Put it this way....I keep up with my friends Peugeot with a Gilardoni 70cc kit, quad reed Malossi valve, 16mm Delorto and a Simionini pipe.

Re: Puch E-50 Polini, et cet observations

If you don't Radius your Polini, you will not have as much power, and you will also seize your engine sooner. There are transfer ports in the jug that are not in the case, so if you don't create them, you will get a hot spot on your piston. Enjoy it while it lasts!

Re: Puch E-50 Polini, et cet observations

It may be late to do, but it'd be nice to see pictures. Two of the threads mention radiusing the case and one the Polini - along with opening up ports in the case where there are none. Be nice to see.

The only radiusing I'm familiar with (in my limited experience) is putting a radius on ports in the cylinder so that the rings don't get caught or worn rapidly. This thread sounds like an entirely different matter, no?

Re: Puch E-50 Polini, et cet observations

"radiusing" is port-mapping (matching)

Re: Puch E-50 Polini, et cet observations

Port mapping is putting a rubbing paper inside your cylinder, and producing a rub of the material so you can see and measure exactly where your ports are in the cylinder and use that information to adjust your port timing, or to make modifications to the cylinder for better flow and power.

In the case of the Metra80 or Gilardoni, where "radiusing" means you have to enlarge the actual sleeve for the cylinder to slide into. Case Matching and Port Matching are what you do when you install a Polini on a Puch, but port Matching and Porting / Port Mapping are different.

Re: Puch E-50 Polini, et cet observations

I.R.E. Mike Pee /

I'll need to do this soon as well. If anyone can post before and after pics of their engine case halves, that would be awesomely helpful to us first time polini folks.

Re: Puch E-50 Polini, et cet observations

"Read this thread": https://www.mopedarmy.com/forums/discuss/read.php?f=7&i=68806&t=68694

Devin from MLM posted a picture in this thread of what ports should look like if they are perfect. I'll take a picture of mine some time and show you what's obtainable if you aren't a Polini master like Devin.

Re: Puch E-50 Polini, et cet observations

Thanks for the explanation RJ!

I do have more questions, if you don't mind. (I always enjoy learning more about these babies).

1) You mentioned that the Polini jug has ports that are not on the Puch case. so does that mean you have to cut entire new ports in the Puch case for effective use of the Polini?

2) I've also heard of case matching, which is where a kit jug's ports don't align exactly with the ports in the case, no? In this case you dremel to get them lined up - correct?

3) There was another thread on Moby's (and likely the same on other models) where there was discussion about lowering the bottom of the intake port and raising the upper edge of the exhaust port in order to get mor transfer. the mentioned radiusing the edge of your enlargements so you don't catch the rings. If you do this procedure (making the opening in the cylinder wall bigger) how far back into the port do you need to remove metal?

4) I also read comments about working on the ramps. In the second picture in the first post in this thread https://www.mopedarmy.com/forums/discuss/7/50431/50431/ there is a picture of the bottom of the cylinder, and in the transfer ports is a divider (like the webbing between your fingers). Are they talking about dremelling away material here, in order to make the transfer ports larger?

Lots of questions, and I have this Malossi kit to pu ton one Motobecane, and I'm thinking about porting the jug I take off to put on my other Moby, and compare the results.

Re: Puch E-50 Polini, et cet observations

Answered a lot of my questions by going to the Wiki and reading Smitty's Cylinder Porting Guide. Very helpful, and makes me realzie that all I want to really do is port matching, not going to get into changing the ports.

What I will do is polish the exhaust ports on both, and I also took note that you want the intakes and transfers to be "roughened", in order to aid in fuel atomization.

Once again the value of the Moped Army forums (and Wiki)comes through!

Re: Puch E-50 Polini, et cet observations

I can competently answer two of your questions.

1) Yes, there are ports on the Polini for Puch that are not in the case normally. There are two of them, and if you look at the gasket laid out on the case, you can see where they need to be. Color this area in with a permanent marker so you can see what needs to be removed. I use a dremel to outline them, and then I have a hand file that is the exact right size and I use that to take the material down to where I want it. The picture in the other thread shows these transfers, they are on the top in the picture.

2) Case matching is for both stock and kits. I've never done it to a stock engine, but I hear it helps a little. On a kit, it makes a world of difference, when you look at how big the transfer ports are on your new cylinder and how small they are in the stock case, there is no reason not to. The case becomes a bottle neck, and those are not good.

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