Pushing the 20mph envelope

Well, today was the day. I am happy to report that my little PA50 I is performing at it's full 20mph capabilities! If you've been reading my other posts about variators and bogging, you'll know that it's been a lot of work to get to this point. A note about carbs though. I had rebuilt and installed a carb I bought off of Ebay, but had bad bogging problems. I believe it was off of a PA50 II. I rebuilt and installed the carb that came with the ped and that fixed my problems. It turns out that the Ebay carb had a #70 size jet in it while the original had a #60, hence the source of my bogging problems. I made a metal fuel line with some poly connectors after the full poly line I installed burned half way through after it came in contact with the head. Either way, I'd like to thank everyone for their help and I am looking forward to my next ped project. Perhaps a pa50 II or a Puch. (I want something that goes over 30 mph and has turn signals.)

Re: Pushing the 20mph envelope

Leon Swarmer /

Well done. Glad you got that little critter up to full throttle.

Your patience has been rewarded.


Re: Pushing the 20mph envelope

Good show! and good thinking about that carb..

Btw, as far as your next bike, it's easy to make 'em go over 30 MPH but no turn signals on the PA50 II..

I'm interested in knowing the differences between the PA50 I and PA50 II. Maybe you can help me out.

The PA50 II comes with an 11.5mm Keihin carb with a #78 jet. Did you notice the size of that stock PA50 I carb? (size in mm is stamped on the throttle butterfly plate). Maybe the next time you drop the engine you could take a peek at it.

The front variators are different.. but I suspect the gear box on the rear wheel has a different ratio. The PA50 II rear pulley turns 12.5 revolutions for each rear wheel revolution. This is easy to determine while on the center stand.

I'm pretty sure of a couple differences already..

PA50 II front variator assembly is able to provide a higher gear ratio. Someone said the cylinder port timing is different. My guess would be the exhaust port is not cut as high up.

Other than those things (and perhaps the carb throat/jet size and gearbox ratio) the bike/engines could be the same.

Re: Pushing the 20mph envelope

Now that you have it running you may want to modify it. First get the PA 50 II variator and install it. (It will take some modification, do a search here to see what they are and how to do them.) You can also get performance parts at,


Because this site is in Europe you will be looking for parts under the name that this bike is known as in Europe. That is the Camino.

Re: Pushing the 20mph envelope

Thanks for the link. I know that some of you guys are running the proma circuit exhaust. Do I have to rejet my carb, modify my reed valve, etc. to work with this exhaust or is it a straight bolt on? Does anyone have the proma sil all (I think that's the name.) Oh, "joew" I will get you some info and pics for the carb when I get a chance.

Re: Pushing the 20mph envelope

go with a puch for the next project

they dont have signals but can be added(if you can find some)

you can make some with a 555 timer as well

puch peds will also do 30MPH


Re: Pushing the 20mph envelope

cool.. pix aren't necessary but go for it if you like.. I'm sure it's a Keihin (on the carb's side.. right next to the fuel line inlet) and I suspect it's a 11.5mm just like on the PA50 II, but with the smaller #60 jet.

Re: Pushing the 20mph envelope

Pretty good discussion about PA 50I, PA 50II, differences and variator mods here:


Re: Pushing the 20mph envelope

Thanks for the link. I'm learning a lot from this website which I'm using to drive my co-workers crazy. :) My PA50 is too nice and too original to cut on, so I'm currently trying to stockpile enough parts to build some kind of freaky PA50 II project.

Re: Pushing the 20mph envelope

Chris Robertson wrote:


1. Compression ratio (PA-50I is 6.9:1, PA-50II is 6.5:1).

2. Air Screw Opening (PA-50I is 1 3/4, PA-50II is 1 3/8).

3. Exhaust port open (PA-50I is 57.5deg BBDC, PA-50II is 65deg BBDC).

4. Exhaust port close (PA-50I is 56.5deg ABDC, PA-50II is 65deg ABDC).

5. Scavenge port open (PA-50I is 45deg BBDC, PA-50II is 47.5deg BBDC).

6. Scavenge port close (PA-50I is 45deg ABDC, PA-50II is 45deg ABDC).

7. Final reduction (PA-50I is 22.767 - 17.446, PA-50II is 22.767 - 13.537).

The final reduction of a PA-50I can be upgraded by replacing the rear hub (or the entire wheel) with a PA-50II's.


Although he didnt mention the carb much, port timing and the rear wheel gear box is different.. Just what i wanted to know.. Thanks for the link, Cyberian

Re: Pushing the 20mph envelope

I agree about cutting the variator or making any changes that are irreversible. The ramp plate on the PA50I is not curved as much as the PA50II.. No 'mods' will transform one variator into the other.

But I have experimented and did find reversible a way to raise the gear ratio on the PA50 II variator.. Top speed increased about 2 or 3 MPH and i've never noticed any difference except the increase in speed. Search Performance tuning forum for what i did if you're interested.

But if you make your engine stronger so it has some extra power, you could replace the rear wheel (or just the gearbox) with one from a PA50 II and you will get more MPH without any drawbacks.

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