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1977 Zundapp ZD40 Moped
http://www.international2cvfriends.com/forum/viewtopic.php?f=5&t=5463		 Page 1 of 2
Author:  smyth602 [ November 26th, 2014, 9:37 pm ]
Post subject:  1977 Zundapp ZD40 Moped
Well, I know this isn't an a-series, but I figure we're all sick of those rattly old tin cans so a change of pace would be nice ;)

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I acquired this bike many moons ago and stuck it in the back of a stable 'for a few weeks'. Weeks turned to months, then years... you know how it is. Anyways, helping my dad try to get his velosolex started the other day was the prod I needed to dig this out and have a bash at getting it running again.

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It was a runner (just) when I got it, but 3rd gear was impossible and it didn't like you giving it more than about half throttle from what I remember.

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My knowledge of 2-strokes is limited, and my knowledge of mopeds is non-existent so I figure this will be a bit of a learning curve. Please forgive the many questions I will inevitably ask!

It came without paperwork, so details are thin on the ground, but through sheer luck I found an advert for it being sold a few years back so I know it was an import from Holland (https://buyvintage1.wordpress.com/page- ... g-tcd-91r/), and thanks to an old mot sticker under the seat I managed to find what I assume to be the first British registration it had before it got a private plate. Originally it was UBJ976R, but has been changed to TCD91R at some point. Details online about this model are few and far between but I think its 50cc or thereabouts.

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So, let the spannering commence! Anyone with experience of 2-strokes, mopeds, Zundapps in general or just feels like hurling some abuse, feel free to comment ;)
Author:  smyth602 [ November 26th, 2014, 9:59 pm ]
Post subject:  Re: 1977 Zundapp ZD40 Moped
Removing the covers from the top of the engine reveal the rather interesting wiring loom and carburettor. The air filter is AWOL - I assume that the lack of air filter will affect running to some degree - will one of the hundreds of generic ones on ebay for a 50cc scooter do?

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Float bowl off the carb - the fuel inside looks a bit murky, but it could be worse after sitting for so long. The bottom of the bowl is filthy, but again not bad considering

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The jet is a bit chewed up but looks clear - a blast through with carb cleaner for good measure.

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With the fuel looking murky I had a look in the tank - seems pretty rusty in there and the fuel looks cloudy, but the filter looks pretty clean so I'm not overly fussed at the moment.

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Author:  smyth602 [ November 26th, 2014, 10:25 pm ]
Post subject:  Re: 1977 Zundapp ZD40 Moped
I had tried kicking the engine over when i dragged the bike out, but there were no signs of life. the carburettor doesn't seem too bad so i decided to take off the cylinder head and have a look inside. The head itself is a bit manky, but a quick clean-off with petrol reveals lots of shiny metal - I'm not sure if i should be worried about the deposits that are left. Rust or carbon?

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The top of the piston got the same treatment - again, seems in pretty good condition, with lots of enigmatic markings - anyone feel like enlightening me as to what they might mean?

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The barrel itself looks good - mirror shine, even! The 3 ports at the bottom are confusing. I guess one is inlet and one is exhaust...the other? I'm new to two-strokes, remember...

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Author:  ken [ November 27th, 2014, 12:28 am ]
Post subject:  Re: 1977 Zundapp ZD40 Moped
Step 1. Take the tank off, put a few handfuls of gravel/pebbles into it plus a litre of water, then give the thing a d@mn good shake, rattle and roll.
Drain the water out, refill and repeat until the water which is coming out is free of rusty bits.

Dry the tank, using compressed air to blow most of the water clear before hiding it in the airing cupboard for a few days, or use a hot air gun for a quick turnaround.

Decoking a two stroke is easy, unless you need to clear out the silencer as well, but with modern synthetic oils and lower petroil mixes, that's not needed as frequently.

Arrow on piston head probably indicates that it should face to the front, exhaust port is the one nearest the cylinder head, the other pair are both transfer ports, through which the incoming 'combustibles' move from the crankcase to the combustion chamber. ;)
Author:  Terry [ November 27th, 2014, 1:15 am ]
Post subject:  Re: 1977 Zundapp ZD40 Moped
I gave a restored 'bike tank the same treatment as Ken describes [above] ....but I used a handfull of clean nuts & bolts ....as an added precaution I attached a strong magnet to the tank .....my theory being that any future rust,will attach itself to the magnet.....so far [15 years later] its worked.
I seem to recall reading somewhere that a bung in the end of the silencer and a filling & soaking of a water & caustic soda solution will clear carbon deposits,although I've never tried it when I was riding two strokes [MZ's btw].
T. ;)
Author:  Diesel Dave [ November 28th, 2014, 6:30 pm ]
Post subject:  Re: 1977 Zundapp ZD40 Moped
I prefer a handful of old nuts and bolts, and pack it into the tumble dryer with the sofa cushions and give it a good 20 minutes on cold.

A good flush with old fuel or white spirit and fit an inline filter.

Sort of the same rules as putting engine parts in the dishwasher - make sure SWIMBO is absent at the time.

Concrete mixer also works but not many have one available.

Arrows on 2t pistons always point to the exhaust port.

Caustic can be used on steel parts but keep it away from anything alloy; if you have never used it before read all the cautionary stuff before you have a go. If you get it on your skin it feels greasy; but this is only because it's turning the fat in your skin into soap.
Author:  citroenboat [ November 29th, 2014, 1:33 am ]
Post subject:  Re: 1977 Zundapp ZD40 Moped
Quote:
- make sure SWIMBO is absent at the time.
= 'So What If My Brother is Out'....? - is it his dishwasher then?

My missus went out for 1/2 hour day before yesterday so I moved the the Guzzi into the conservatory... Last taxed 1996, been in my shed last 5 years, carb strip & clean, (rebuild kits ordered) and we have a runner! An old nail but it works :D :D :D

Bit of light relief from rebuilding the van....
Author:  smyth602 [ November 29th, 2014, 11:38 am ]
Post subject:  Re: 1977 Zundapp ZD40 Moped
Quick update - put the top end back together and had another go at starting it up - IT LIVES!!! But not very well. Idles okay when cold but dies after a couple of minutes. Won't really run at all without the choke and cuts out on anything past about half throttle. I think this indicates running too lean? My carb strip-down was pretty basic so I'll try giving it a full disassemble and clean and see how it goes. The seal that the float bowl seats to looked pretty ugly so maybe sucking air.

Nice idea on using the tumble drier, DD. I'll give that a try soon, although not sure how the other half will react. I was amazed when I asked how she'd feel about me bringing it into the living room to work on as it was pissing down outside - instead of the earfull I expected, I just got "Do you need a hand bringing it in?" :o

It seems to me like its had some rewiring over time from comparing what is there to an old wiring diagram I found online, my assumption being that it needed some changes for a UK MOT - wiring diagram only shows single-filament bulb and no horn, unlike mine.

Attachments:
Zundapp-ZD40-Wiring.jpg
Zundapp-ZD40-Wiring.jpg [ 118 KiB | Viewed 6960 times ]
Author:  AZL57 [ November 29th, 2014, 5:34 pm ]
Post subject:  Re: 1977 Zundapp ZD40 Moped
Didn't see those often overhere. Here we had more this model...
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Author:  smyth602 [ December 31st, 2014, 4:15 am ]
Post subject:  Re: 1977 Zundapp ZD40 Moped
I've been moving house and job-hunting recently on top of Christmas shenanigans, so not much has happened with this until today, but I had some free time so I thought I would have a poke and prod.

The carburetor was easy to strip down - I had the float bowl and jet off before, but i figured it would be worth checking the whole thing over, as much to see how it works as anything else...

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I had ordered a new gasket set from Germany before xmas which arrived today. The remains of the old float bowl gasket were painstakingly removed in tiny bits and the strip-down had revealed that the lid gasket was missing entirely - probably the main cause of it running lean, along with the air filter being missing.

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The bottom gasket from the new set fits fine, but the top one is way too small - turns out I ordered the wrong set :oops:

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While looking for a proper-sized set, I found that a replica carb is only £30, so i will probably just get one as the correct gasket set will be about 15 delivered and the carburetor I have at the moment has other damage - crushed priming valve cap causing it to stick as well as some worrying gouges out of the body itself. Originality vs ease of fix...opinions?

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