New TS250 Owner

[Prusakowski-Ost]

New tires on the TS250 since 1974...the DDR original tires looked good....but were very dry.

[Puffs]

Pneumant's - thanks for those pics! Quite some cracking, but otherwise they still look quite reasonable.
Did they have a (DOT) date code?
Since 2000 the date code is WWYY, but before 2000 that was WWY (I think). So it might look like WW4 - if they have any...

[breakwellmz]

Chuck them!
They were bloody awful things when they were new especially in the wet, even worse with age!

[Blurredman]

I don't think they're all that bad performance wise.

20 year tyres I would ride on and have, sure. But 40 no. Well, maybe on a car I would.. It's not so much cracking that's the issue but if you can see the carcas that makes up the tyre. As for tubes, I don't replace them unless the stems break... or in the case of one of my Pneumant tubes years ago I had tested it between changing the tyres and it pumped up to the shape of a square!

These days even really cheap tyres are very good at their job though.

[Puffs]

IMO it depends on how you ride & what you expect of your tyres / bike. Rubber hardens over time & gives less friction with the tarmac. It may start to slide without warning.
On old bikes, riding conservatively & at slow pace, it doesn't matter so much and I've had 20+ year old tyres on such a bike. But it's always a risk, and if you lean or otherwise rely on grip, you'd really need young rubber. As they're off, looks like the OP already has decided.

I never had any Pneumant tyre, but Pneumant became Heidenau (a bit like how DKW became MZ), and I currently have a Heidenau K36 at the R on my 251. It performs well & seems to last decently there. And looks great!

[breakwellmz]

That`s all good and fine until some idiot pulls out in front of you, you brake and the tyre locks up rather than grip the road!
As you said "I never had any Pneumant tyre". I have!

[Puffs]

Heidenau K36 is OK, though it may a bit difficult to seat properly in the rim. This is what it looks like:

Heidenau K36.jpg (29.84 KiB) Viewed 484 times

Enjoy Xmas!

[AlanJ]

Hi Guys,
First off, I hope you all had a great Christmas and the new year gets something sorted with these blasted viruses, although the way our
governments are dealing, or not,and, sadly I doubt it. Anyway, that's another subject.
Tires/tyres, when I was working, I seem to remember that our tyre man at Ford research engineering centre, said that tyres should only be used for 7 years
always assuming there is no damage during this time. If you ask any person using a caravan, you will find that most will have had a blow out at
sometime or the other ( not much fun) Ultra violet is the biggest problem with age, the tyres harden and dry out somewhat, and as mentioned
the tyre loses grip. The odd thing is in GB if you go with a car for an MOT test with 20 year old tyres, it will fail the test, even if the tyres still look ok,
but, if you do the same with a bike it will probably pass the MOT test. Perhaps the bike testers don't look at the tyre wall indicators, I don't profess
to know that much about tyres but at my age I can't chance a flyer on the corners, so I stick to inside 10 yrs.
Wish you well Alan.

[Puffs]

Agreed & hope you had a good one Alan!

[AlanJ]

Hi Guys,
On the previous post, I mentioned that Ford Engineering recommend the life of a tyre as 7 years as I said, providing no damage
but that is of course, for a car tyre, and when I looked up the recommended lifespan for a bike tyre it was 5 years and to be honest
the reasons are obvious. Flexibility is high on the list and age and stiffness brought on by ultraviolet is obviously a problem to that flexibility.
Anyway Guys it's up to you, of course.
Stay safe Alan.

[Puffs]

Yes UV radiation causes all sorts of effects. It can tan our skin, it can cause skin cancer, and also cause many plastics & rubber types to decay & microscopically decompose. With bikes being kept indoors, out of direct sunlight & UV, the effects on tyres might be less, but I suspect that the rubber also hardens just with age. Temperature will also play a role, as it is a common view in road racing that tyres that were kept too long in the tyre warmers perform poorly.

[Prusakowski-Ost]

I knew the fun wouldn't last long....old seals...bike sitting for decades...the old seals finally perished. I got a whole ten miles on the bike from start-up to shut down because of losing compression. Can anyone give me a hint on what seals I need to replace to get this bike up and running again?

[Puffs]

Welcome back!

Well, all the parts, with sizes and official MZ parts numbers, are found in the relevant Ersatzteilliste zip file on miraculis.de, take your pick. Or just order them from any of the parts vendors, or measure what you need and get it over the counter from local supply. You'll also find manuals there.

But why would a loss of compression be caused by seals? It is possible that the seals on the crankshaft leak, and that will give running issues, but not so much loss of compression. Instead I'd rather suspect something with the piston rings. Maybe they scraped some deposits from the cylinder wall (rust, maybe?), which caused them to stick in their grooves? If the bike has no compression, and the head was properly torqued, I'd take the head & barrel off, and look at that. If there is rust, it is also quite likely the conrod bearings & main bearings will fail relatively soon. Sorry to mention that, but rust inside is bad news.

You can clean the ring grooves in the piston with part an old ring, if you have that, ground sharp. The grooves have to be clean, even, and not too wide, the manual may specify a clearance with the rings (but I'm not sure).

Good luck!

Edit: for your convenience the relevant drawing for the TS250:

17.gif (10.45 KiB) Viewed 484 times

It'll be items #14, crankcase seals D 30x62x10, both left & right. It is possible they are dried out & hardened, and therefore do not seal, but if they are worn due to rust you'll also have pitted corrosion in the bearings.

But once again: for loss of compression I'd start by taking the barrel off & look at the rings.

[Prusakowski-Ost]

The MZ TS250 in question was stored inside for 40 years...with all fluids drained out of it....including the case oil. I'm sure once I started it up after its long slumber, the seals (item 14) failed. One other variable I forgot to include is once the bike stopped running, and I parked it for the evening, there was a small puddle of oil coming from the left side of the bike. I understand both seal 14 are only accessible by taking the engine case apart....or can they be removed from outside the case?

Many thanks for the diagram!

[Puffs]

OK, here are some links for you:
Spare parts list: http://www.miraculis.de/aw/download/mz/ts250e.zip
Workshop manual: http://www.miraculis.de/aw/download/mz/ts250r.zip
Workshop manual: ftp://blurredmanswebsite.ddns.net/Vehic ... Manual.pdf
User manual: http://www.miraculis.de/aw/download/mz/ts1525b.zip

The ones from miraculis are in German, but there are a few browsers which include automatic translation of an HTML text.
To translate a HTML browsed in any browser, enter the text "https://translate.google.com/website?sl=de&tl=en&u=<desired URL>" into your browser's address field. In that,

sl = source language
tl = target language
u = URL

Obviously adapt as required.

Note: these links are for a TS250, if yours is a TS250/1 you need other documents.

On the technical: this is a two-stroke engine. Seals #14 isolate the crankcase from the gearbox and the oil from that. There is normally no oil in the crankcase, lubrication of the conrod bearings and the cylinder/piston is by oil in the premix, while in this model the main bearings are lubricated by gearbox oil. See this pic:

2G.JPG (31.64 KiB) Viewed 484 times

If the engine leaks oil, it is not due to the crankshaft seals #14. Possibly the drain plug is leaking, or maybe it comes from the gearshift lever, output shaft seal, or something with that clutch thingy. Look carefully where it comes from (which is probably not exactly above the puddle of oil on the floor).

I'd be surprised if seals start to leak just by time, normally wear is required, but it is possible. It's also possible that during the initial running much accelerated wear was caused by some corrosion on the shaft that should be sealed. Nevertheless, the oil leak is probably not the cause of your running issues.

If you feel no (or a reduced) compression on the kickstart lever, I recommend you take the barrel off, and inspect bore/piston/rings. That is quite easy to do, and for instance insufficient lubrication (did you premix properly?) may also cause your problem.

On this model I don't think you can replace the seals #14 without taking the engine apart, the main bearings are in front of them.