My new (old) MZ

[tomx]

Hi,
First time on here, so hello. I've spent plenty of time around older Jap bikes, and last year bought a Simson for my (half German) step daughter. Ended up looking like this :-

Last weekend I picked up this little beauty.

At least I can see the beauty under the rusty exterior.
Step daughter is now 17, and would (I think) like to have a bigger bike. The Simson is lovely, but this 125 is a bit bigger. I was very pleasantly surprised to find that it works, it is 12V and has oil injection. Almost modern! I have a few things on order to tidy it up, but it shouldn't need much more than paint and some re-wiring.
Wish me luck.
Any advice people can give would be very much appreciated. I've never had a 'proper' MZ before, so this should be fun.

[DAVID THOMPSON]

fix it nice and it will serve a long time
and unlike some older bikes if you look you can actually find parts for it
dave

[arry_b]

That's an excellent candidate for tidying up, I tend put two or three ETZ125s back on the road every year, just to keep me out of mischief.

Lessons I've learnt:

Change the fuse box for a bladed one. Don't think about it, just do it!
Black stove paint is cheaper, blacker and lasts MUCH longer than VHT on MZ exhausts.
The rev counter drive inside the engine loses it's teeth, don't worry about fixing it as they're not much use - I stick a small digital clock on the rev counter glass, far more useful.
A braided hose on the front brake works well, but a new rubber hose makes it feel nicer - the braided one makes it feel wooden.
Check the primary chain and sprockets. These can get very worn and the engine rattles a lot. It also can throw a lot of swarf around the gearbox, which isn't good.
Replace the pipe between the oil tank and the oil pump. The original goes hard and leaks/sucks in air.
Check the oil pump cable for frayed strands.
A Morris Minor air filter fits the filter housing, and works fine. Far cheaper than an original.
Crank seals (if you need to do them) are easy on this engine, you don't need to split the cases.
Upgrade the front light to a Halogen - P45T base. Around £6 and makes a massive difference.
Mitas Tyres and very cheap (oponeo.co.uk) and work really well on two stroke MZs
The forks are a little on the soft side. A few 2p pieces in above the fork springs makes a big difference (8-12 pence a side?)

It's worth putting in an order for the parts in one go to ost2rad.com, some of the stuff you're going to need (gaskets, mirrors, seat cover, rubbers for grips, levers, cables etc) cost buttons and are generally good quality.

Once finished, she'll find it good to ride. The brakes, and lights and handling far exceed most other 125s out there. My daughter passed her test two years ago and won't give hers up for a bigger bike, it's the same as the one you have there. My lad's got a slightly later one (1992) and it's not as well made.

BTW, nice job on the S51.

Steve

[tomx]

Thanks for that, all really good advice.
My first box has turned up from Ost2rad although the main things in there were the tyres. I've used Heidenau on both the S51 and our SS50 and I like them. I've never trusted tyres from the far east after falling off too many in the rain in my youth. I was put off the Heidenau after I found they were from the Pneumant factory, but I'm told they actually use rubber in them these days.

We have family from East Germany, and they pointed out that most of the roads were not tarmac, so Pneumants were just fine. They also outlasted the bike.

I will take your advice and check the oil lines, as well as the primary drive. Headlight as well. 12V makes life so much more sensible.

Thanks about the S51, it wasn't too bad when we got it, just needed paint and a few new chrome bits. As you say, they're so cheap it's daft not to. SInce that photo I've changed the spokes, handlebars and indicator mounts for new shiny ones. It's a nice ride as well, for a 50. As I'm a seriously overweight bloke it takes a good 50 to keep me moving and this one just keeps up. I hope the 125 will be even better. My main bike is an ST1100, and that keeps up. Just.

Cheers.
Tom

[tomx]

Thought I'd just keep adding photos in here, as it comes apart and goes back together.
Tank off :-

Bit of rust but nothing too bad.
You were completely right about the oil feed pipe, brittle as anything, so replaced with rubber hose and bled through properly.

Horn now works. All the connections are a little corroded. Nothing unexpected.
Funniest thing was the ampount of water in the indicators. Lot of rust in there so on the list from Germany.
Panels and airbox off and painted. Hi gloss black is so easy to get fairly decent.

One thing I noticed was the coil getting very warm when not running. Is this normal? I can imagine current going through there from the battery but it shouldn't get that hot should it? Does the coil run off the battery or is straight if its own coil like the smaller bikes?

[arry_b]

The coil runs straight off of the battery, so if the engine stops withe the points closed you can cook the coil.

It's fairly common to need a new coil when recommissioning an old MZ two stroke. My pet theory is that a good number of them get taken off of the road because of a faulty coil (bike runs for 20 - 30 mins, then fades away and dies).

[DAVID THOMPSON]

The coil runs straight off of the battery,

my my in that case it needs to be hooked up some other way
or have a relay that hooks it up when key is on
dave

[tomx]

Well it does have a decent spark but I haven't run it for any time as yet. A new coil will not break the bank. I saw the wiring diagram has the generator running into the battery and points, so I asumed it was always powered up. Not a great design.
At the moment I'm just tidying it up, and will find out how it runs once it's all back together.

Must get rid of nasty Chinese tyres. It might rain...

[DAVID THOMPSON]

the Heidenau tires came stock on my rt125 in 2002
when they were replaced. there were no shops selling them here
so i used kenda 671
but now there are some shops that sell them
so will try to find a set for the rather odd size on the rear of my saxon tour
110/80-16
i liked them. it rains a lot here
dave

[tomx]

A couple of photos as I go along.
Firstly the tank after a couple of coats of gloss black. The frame has just had a brush over so looks a little better. I'm not going for any awards here, just some degree of protection. The seat was the cheapest from Ebay, and a later unit but it will do for now :-

The side panel as well, with its coat of gloss black and a new sticker :-

Not the best finish, but it will do for now. Have the engine to clean up next.

Last time I was in WV it rained on me. My godmother lives in VA, and I my ex wife is from NJ, so I vaguely know the area. Anyone riding a bike in NJ traffic is either brave or stupid. Chinese tyres in the rain are just asking for trouble in my experience. I buy the Heidenau tyres from Germany as it's cheaper than getting them here in the UK. Something to do with exchange rates and cheap parcel service I think.

[tomx]

Painted the engine cases. Just some satin black and a brush. Looks OK though..

Tank looking good too. Second box of bits arrived from Germany. New exhaust still to go on.

[tomx]

Front wheel off. Bit of corrosion there....

I have since cleaned it up and painted the hub, but for some reason the new spokes are a couple of nipples short.
Is it me?

[tomx]

Front wheel tidied up and new spokes fitted, along with a new tyre. Looking better. Ready for all that sunshine...

Just the back wheel to do and a whole lot of work for the MOT but it's all together now.
All good fun. Maybe I'll get to ride it soon...

[tomx]

Got it through the MOT, looking a bit better now I think.

Just done the rear wheel, new tyre, and painted up the rear end. The test run did not go well. Terrible misfire. I have a new coil, points and condensor, so I hope that cures it. I also have a new carb to go on if the electrics don't help.
I'll see how it goes with the electrics.
Crap in the tank doesn't help. I've had to empty it and clean the filters. Must be sure the strain the fuel before I put it back in.
Also have to change that seat. And the exhaust, it does leak a bit, as well as looking awful.

[DAVID THOMPSON]

looking like a daily driver
do not get it tooo nice some one will nick it !
dave