Puch Magnum II - Untitled Thus Far

I'm not sure if this is the exact right place to put this, but it's as near as to what I'm planning as anything else.
I'll let the pictures speak for themselves:








It's a 1980 Puch Magnum II, with a 50cc 2-stroke 2-speed ZA50 engine. This is my first bike, and my first bike build. I've been toying around with bicycles for the past five/six years, and this just seemed like the most logical step up. Not to mention, the dude who sold it to me let me ride his tricked out 'ped and I was hooked on 2-strokes instantly.

I bought it about two months ago, was running okay at the time. rode it around for a week or so, fell in love with it, but had to make some dates and meet some folks. After a month of vagabonding, I'm back at the parent's house for a little bit, working at my dad's office and cleaning up my act, deciding what I'd like to do in the near future. It seems that this little moped is in the immediate future, as i need a project to keep myself busy and progressing. It started acting up a little, partly due to my fiddling, exchanging heads/rejetting/2stroke majik.

I plan to ditch the clubmans and stock seat, put some smaller motocross, 1 or 2 inch risers on, not too tall, build a seat (see next post) and eventually repaint. It's the only bike I have, so any bonus dough I'm not saving will probably end up somewhere inside it or coming out of the tailpipe. Right now, some jets, some hardware, some cables and a fat little expansion chamber are whistling their way towards my house on a ups truck ; phase II of the master plan happens tomorrow.

This is my bike, and I am so pumped to get it running right and get riding. I need some motorized transportation, I need a project...

Plus I need some thunder under my buns.

Here's the seat I'm in the process of building. Thus far, it's cost me about five bucks, what with a few thrashed skateboards lying around the house, as well as a donor mat and an old pair of blue(black) jeans that have long since become swiss cheese. The form is looking good, and it all fits except for a misguesstimation on the length of bolts needed to seat it correctly - hardware store tomorrow. I haven't shown it, but the layout for the denim material looks like it'll work just fine for now - I just want to prepare a decal or something and wait till I have the right length hardware underneath the foam layer. If you're wondering what the second layer of ply is for up near the tank, the Puch Magnum has a neato little system of mounting the tank in which there are two little gummi knobs up in front that correspond with two forward-facing c-shelves in the front of the underside of the tank, and then a second gummi under the back end, which simply sits on a level and waits for a seat (such as the stock one) to clamp down over it. I've made the poor-man's version of the seat clamp with the remainder of the skateboard and some shims/woodscrews, simply resting and pressing down and forward on the tank. when it's screwed in. I'll take a picture tomorrow - gotta sleep so I can wake up to go get my back cranked on.

The ZA-50 is a good solid motor. There's a ton you can do to it, and they're so simple, and there are a ton of parts for it.

You're probably going to want it to go a bit faster than 30mph though.

A simple first step is a new pipe. My first pipe was a biturbo. Make sure you up-jet your carb so you don't seize.

If you want to go any crazier, You'll have to do a bit or work on the clutch first. Fist thing, replace the dampening pucks in the second speed clutch. If you don't, you risk breaking your motor. This can sometimes give the ZA50s an undeserved bad reputation for being poor engines to tune.

Once I decided that 30-35 wasn't cutting it (my local moped club has some really fast bikes, and they've been getting faster, and I was having trouble keeping up on rides) I sold my biturbo to a girl in our local club and got the Techno Estorl, a 15mm carb and a 70cc K-Star with Hi-comp head kit. I put new race pucks in the second speed clutch, and flipped the first speed clutch. This takes you up to 25 before the second speed engages and evens out the power. A good setup will let your engine rev a lot higher and give more power on the top end, so it's really realistic to get up to 25 in first.

I'm pretty sure that I could eek a bit more power if I went back in and case matched the case to the cylinder a bit better, and stuck a better carb on it, but it goes 50, and I can wheelie it, so there's isn't much more I want from it. These mopeds definitely don't handle like a bigger bike does, but they're a blast to ride.

I've always wanted a moped, but at 6'5" I look beyond ridiculous on them. noexit is right though, there is a ton you can do to these motors. Fun as hell to wrench on, and easy too.

As far as i know, Flickr is a photo-uploadsite for pro's. Therefore, images can't be linked. It has to do with copyright issues. Instead, use Photobucket or similar. Correct me if i'm wrong!

Bert Jan said:

As far as i know, Flickr is a photo-uploadsite for pro's. Therefore, images can't be linked. It has to do with copyright issues. Instead, use Photobucket or similar. Correct me if i'm wrong!

Click to expand...

Correcy. Flickr doesn't allow embedding in other sites.

Nice... There is a guy in my neighborhood that rips up and down the street on a bike just like that....

noexit said:

The ZA-50 is a good solid motor. There's a ton you can do to it, and they're so simple, and there are a ton of parts for it.

You're probably going to want it to go a bit faster than 30mph though.

A simple first step is a new pipe. My first pipe was a biturbo. Make sure you up-jet your carb so you don't seize.

If you want to go any crazier, You'll have to do a bit or work on the clutch first. Fist thing, replace the dampening pucks in the second speed clutch. If you don't, you risk breaking your motor. This can sometimes give the ZA50s an undeserved bad reputation for being poor engines to tune.

Once I decided that 30-35 wasn't cutting it (my local moped club has some really fast bikes, and they've been getting faster, and I was having trouble keeping up on rides) I sold my biturbo to a girl in our local club and got the Techno Estorl, a 15mm carb and a 70cc K-Star with Hi-comp head kit. I put new race pucks in the second speed clutch, and flipped the first speed clutch. This takes you up to 25 before the second speed engages and evens out the power. A good setup will let your engine rev a lot higher and give more power on the top end, so it's really realistic to get up to 25 in first.

I'm pretty sure that I could eek a bit more power if I went back in and case matched the case to the cylinder a bit better, and stuck a better carb on it, but it goes 50, and I can wheelie it, so there's isn't much more I want from it. These mopeds definitely don't handle like a bigger bike does, but they're a blast to ride.

Click to expand...

Made an order from treats early this week, waiting on a Tecno Circuit pipe and a handful of other things (namely jets so I can downjet because it's dying at idle presently.) I've heard about putting shift pucks in and flipping clutches, but I'm a little tentative to start digging around in the tranny. I've heard some nightmare things about shims. Also, going fifty and doing wheelies? YOUDAMAN! Seriously, that's impressive! I'd love to see that kind of performance on my bike someday soon.


I've been riding with the Cranks (my local moped club) for a little while now, and I've been riding either this or a loaner from a friend - they're fun to ride! I have no perspective on how a big bike handles, but these things aren't exactly whiptastic (yet.) I'd have expected them to be a little easier to handle, but I've already laid this one down once and went over the handlebars of another, both around corners. This also may attest to my 'energetic' riding style and the poor quality of roads in Milwaukee.... but it looks like the moped experience will be a good one to have before I put anything more powerful between my legs and the road.

Oh, and I'm 5'10 and 125 lbs, so this bike looks pretty normal on me.

And I'll be changin' photo embed sites as we speak.

I wouldn't worry too much about the shims. Just put them back in the correct spot. When you pull the transmission cover, loosen the screws and give it a couple firm smacks with a rubber mallet to break the gasket free. You should be able to remove it without tearing the gasket. If you do, the thinnest gasket material at your local autoparts store is the correct thickness to cut a new one.


If it's currently rich, a non-stock pipe will lean it out.


I don't know if the Magnums have the same forks at the Maxi, but my stock Maxi forks are really flimsy. I don't feel very solid on it while cornering. I've heard that the EBR forks are a great bolt on fix for this.

noexit said:

I wouldn't worry too much about the ...
...cut a new one.


If it's currently rich, a non-stock pipe will lean it out.


I don't know if the Magnums have the same forks at the Maxi, but my stock Maxi forks are really flimsy. I don't feel very solid on it while cornering. I've heard that the EBR forks are a great bolt on fix for this.

Click to expand...

I'll leave the jetting then for now and bolt the pipe on, but I'm gonna need to clean the tank before I run it any more. I'll mess with the tranny later - it seems to be shifting alright for now, but I'd like to take a poke inside.
I'm definitely considering the ebrs as well as some new rear shocks - mine are pitiful.

Thanks for the input! You're a big help.

Also, Treats order just came in! Tecno Circuit pipe, big sprocket, brake pads, jets, the works. And a New York Lock/Fahgeddaboudit chain from Kryptonite so I don't lose my investment here.

I am a big fan of that pipe. I love me a good moped.

Working on the seat. Since it's pretty heavy ply, the staples don't go very far in, and I get half of the staple sticking out when I press my hardest when punching them in. Any recommendations as to how to do it in a nicer, neater fashion?

Attached the new pipe, made a bracket for the rear with some scrap metal I had lying around, and it doesn't look half bad... or conspicuous. Took off the rear fender and light to clean and service.

Haven't run it yet - have to change the brake shoes in the back and give it a little clean-up while i've got the wheel off.

Next post, I'll put up some pictures of the seat, which should be done by tomorrow. Gotta get upholstery tacks...

JustinLonghorn said:

I am a big fan of that pipe. I love me a good moped.

Click to expand...

Seriously, Justin has a nasty addiction to 2 stroke smoke. Moped guys are a little nuts - I love it. Carry on with the good work man!

Got it running! And braking!


It's idling pretty solidly, even after warmup (a feat this motor couldn't accomplish before.) I kept it jetted the same - will be doing a little needle/idlescrew work, but it feels fine. Tank is still rusty, but I bolted on a tank from one of those chinagirl motors as a temporary fix and so that I could run it and test it. Sounds nice and poppy, but unfortunately am getting a fair amount of noise from the ZA box. This isn't new, but it is a reminder that I may have to go in and replace some things, and soon. Don't want any bearing seizures, etc.

Waiting on some upholstery tacks to finish my seat. Looking good - a tiny bit irregular on one side, but not so much as you'd notice if you weren't looking for it. Pulled off the side covers, thinking of selling those too and making some custom work (for more upgrade parts and general bucks.) but I'm not sold on it yet.

I'm going to be riding and tuning, replacing cables and bars today. Maybe take the front brakes apart and give 'em a scrub. When it starts to get dark, I'll probably have to go inside and do some work, but I'll put up some mockups for future plans as well. Any ideas accepted, and if you know any good resources/pictures of good fender chops, let me at 'em.

Consider me tuned in...

I have a Vespa Ciao in my barn that's been in the family since it was new, my dad got it when he was like 10... Moped parts are cheap, I think I may slowly start building it. I'm feeling a 65cc kit.

Dirty Dan said:

Consider me tuned in...

I have a Vespa Ciao in my barn that's been in the family since it was new, my dad got it when he was like 10... Moped parts are cheap, I think I may slowly start building it. I'm feeling a 65cc kit.

Click to expand...

Definitely. I'm not kitting mine yet because it's a 2-speed and I hear it's hard to change the crank to something a little more substantial. And honestly, right now, I think it's all the speed I need. Last time I rode, I laid it down and went over top the handlebars on a corner because I was taking it a bit fast and hit a big hole in the blacktop. Big motor boner gets in the way of me thinking.

thunderhead said:

Definitely. I'm not kitting mine yet because it's a 2-speed and I hear it's hard to change the crank to something a little more substantial. And honestly, right now, I think it's all the speed I need. Last time I rode, I laid it down and went over top the handlebars on a corner because I was taking it a bit fast and hit a big hole in the blacktop. Big motor boner gets in the way of me thinking.

Click to expand...

There's really no need to change the crank unless you're going really extreme. If you are going extreme, Treats has a full needle bearing 2 speed crank. If you're kitting, you'll be splitting the case anyway, so you've already got the crank out.

Like I said, there's a lot of fear that the ZA50 engines are too weak for kitting, but it's really unfounded.

But I do understand your not wanting to crash.

noexit said:

There's really no need to change the crank unless you're going really extreme. If you are going extreme, Treats has a full needle bearing 2 speed crank. If you're kitting, you'll be splitting the case anyway, so you've already got the crank out.

Like I said, there's a lot of fear that the ZA50 engines are too weak for kitting, but it's really unfounded.

But I do understand your not wanting to crash.

Click to expand...

It's good to know someone with experience can assuage my fears - I've heard mixed reports, but it's the engine I've got and I'd like to make the most out of it. Right now, I've got a china-girl tank and a homemade seat strapped to it and I'm perfectly happy to go tearing around my neighborhood to try out my new pipe. I'll worry about that kitting business when money allows - I think I'll do a little clutch flipping and shift-puckin' before I start thinkin' about big bores and reed valves. You gotta get in her pants before you can start thinking about messing around with her head. Engines, you see.

Update: It's rideable.... barely. :/ Took it out for the first time this morning - it was fun, but something's holding back yet.....

My tank is rusty, so I strapped one of those china-girl motors' tanks on temporarily. I've since redone the rear brakes and am breaking them in. Seat's finished, and is pretty darn comfortable. I even got the throttle to stay put on the handlebars with a little sanding and pretty risky filing job. My front brakes and rear brakes need some adjustment, as well as a replacement for the cable-catcher replacement I fabbed up... It snapped as I was hauling ass, so that was a little scary.

But all of that's basic stuff. Here's where I have to summon the 2-stroke wizards... Much like the last week I rode it, it's acting funny. A lot less noticeable than before, but still an issue - Whenever I've been taxing the engine in any way, especially after it's warmed up, and come to a stop, it chugs and almost dies - I have to give it a little throttle to keep it going. It used to not even idle. Now, with the pipe connected, it idles after a little persuasion and stays idling.
My theory says it's either still jetted too highly, or possibly an issue with timing that's a liiitle too far advanced.

What say you?