New member intro and TS250 fuel tank size question.

[Kruh]

Pretty cool. I've never seen that measuring cup.
My TS250/1 doesn't have it, and I see no sings it ever had one.

[Blurredman]

Okay I found some TC grade 2T oil (Lucas semi synthetic) and going to run that on 40:1 based on previous owners recommendation. Now I just need to figure out a solution to carrying around/measuring the oil While on the bike.

All my two stroke MZs (I`ve had five of them) had a measuring pot on the underside of the filler cap marked 33:1 or 50:1 depending on engine size, doesn`t yours? Carried a bottle of oil behind a side panel.
Mine certainly all had long and hard lives, be it hard road miles or (in the case of the trail bike versions) Low speed running with cooling fins clogged with mud, all good.
Remember, they are relatively low revving engines NOT racing ones and the more oil you add the leaner you are making the mixture.
Each to their own at the end of the day but i think the manufacturer have more idea than us mere amateurs.

I carry a half litre bottle in my rucksack- which is something I feel naked without these days. I need it to carry work stuff anyway so it's no biggy- it can also carry bike repair tools


33:1 = roughly 530ml of oil per 17.5l, 50:1 is 350ml. There's only 1 percent difference in oil ratio- The ETZ official service manual didn't see it worth mentioning any difference in jetting between the pre-mix and the oil pump models.

[Puffs]

I don't have such an oil cup on my MZ either, but I have something very similar on a 2T electric generator, in PE.

I always carry a bit of oil with me (in the battery area), just in case, but if I plan to mix at the pump I take a set quantity of oil with me, and fill up with the desired amount of fuel. And then, after I ride away, a bit of acrobatics to mix it. Just to show oil + fuel do need shaking to mix well, this is what happens if you just add the (red) oil to the fuel, without shaking:

Shake it.jpg (27.9 KiB) Viewed 123 times

Anyway, some more comments:
• I did about 25k miles with my 251 & I measured my oil pump (before I took it off), it did pretty much 1:51 on average. Proper adjustment is very important. And yes, when you have the thing idling while you open the oil pump's control thing, pretty quickly it starts smoking, but that is just because then the pump thinks you're giving full throttle, hence assumes far more fuel is entering the engine too.
But either I could not trust my oil pump (though it always required a consistent quantity of oil, and it never ran dry), or the amount of oil it got, 1:50, was insufficient for my riding style (it gets quite some full throttle). I say this because in the more distant past I lost a small end, and more recently I saw grinding marks on the piston than can only be attributed to insufficient lubrication. And this while I have always used fully synth, or a good semi synth. So I took the pump off & premix 1:33 = 3L oil/ 100L fuel, instead of the recommended 1:50 = 2L oil/ 100L fuel. And now all is well. Quite possibly 1:40 = 2.5L oil/ 100L fuel would work too - but why bother?

• I did not say depending on the application, I said depending on the objectives, and that's exactly what I meant. Objectives & priorities. My objective here is to keep the thing working as well as possible at the lowest possible costs in terms of expenditure & effort. I do not mind if there is a bit of smoke from time to time, though my MZ does not actually smoke visibly, with this oil. (My Jawa does, on full throttle & high revs, and my riding buddy once told me 'I could see you had gone past here, from the puffs of smoke' - hence my name.) But I suspect MZ wanted to achieve a greener & cleaner image, even with all the Trabants & heavy industry, so for them preventing smoke (their oil smoked much more) was a priority, and I suspect that played a role too in their 1:50 recommendation. It should be, as in the end pollution was the demise of the 2T.
So, you see, the objectives & priorities of the mere amateur can differ from those of the manufacturer, and yes, as the owner of my bike I will sail my own course.

• Yes, that is correct: if you take out the pump & go for premix instead, the mixture gets leaner. For (at least) 2 reasons. Firstly, a metered amount of fuel (mix) now only contains 97% of petrol, while the other 3% of semi synth will exit largely un-burnt through the exhaust, hence absorb little oxygen. Secondly, and this is more difficult to quantify, the viscosity of the premix is likely a bit higher than of pure petrol. With the fluid being metered by jets & a set ΔP, the flow will be slightly lower if you were to use the same jet.
So you get less fluid, and the fluid that you get contains only a fraction of petrol --> the mixture gets leaner.
All anticipated, so the jetting was adapted in the process.

• These engines (250cc ETZ's) have been used extensively for racing, particularly in the UK. See https://www.youtube.com/watch?v=fyXNoMw4ki8.

• Breakwellmz, would you have any pics of your MZ's? I'm particularly interested in the trail bike versions. Ta.

Edit: sorry Blurredman, hadn't seen your latest post. If there's no difference in jetting recommendation in the manuals, that's once again an indication of the dependency of those recommendations... Sail your own course.

[R1100purist]

Hi all as the original poster, I really appreciate all the input! It’s seems like you can go wrong with a quality 2T oil at a mix 50:1 or even a tad richer if that’s something you’re concerned about. Either way I need to get myself one of those cool gas caps with measuring cup! I’m always making a mess.

I’ll continue to clean up and sort my MZ and post more pics and questions along the way.

Thanks again!

[parrbd]

I use chainsaw oil in my 84 ETZ (owned since new) because it is available everywhere in my area. I looked on the label of my makita oil and it is rated JASO FD. The other brands are probably the same. I tip in to the tank one mililitre for every kilometre since the last fill up (eg 250km means 250ml) and then fill her up with the bowser. At my fuel consumption, this works out at about 45:1.

[breakwellmz]

The filler caps with measuring pots must have been only for the UK market, i think the wording was something like " fill to mark for 1 gallon 50:1" I have one in the garage i must check.
As i`m sure you know the UK gallon is bigger than the US gallon.
My Gas Gas Pampera TRAIL bike ran on 50:1 but forum discussion would be about running less oil rather than more.

https://www.ebay.co.uk/itm/MZ-125-150-2 ... 4311231950

https://www.ebay.co.uk/itm/D-60-Fuel-Ta ... Sw8d1fXRer

https://www.ebay.co.uk/itm/1978-MZ250-T ... SwYrZeUZM1

[Guesi]

The ES models had to use 1: 33 because of the gudgeon pin bearing.

The later models had needle bearings, so MZ changed the recommendation to 1: 50.

Using more oil does NOT mean the lubrication gets better, it means that not all the oil can be burned and so there will be more carbon deposits on the piston and piston rings.So Piston rings can stick...


But do whatever you want

By the way:
Someone asked what MM and EM means on the description of the MZ engines, like EM 250 or MM 250/3 or MM 250/4.

MM means Motorradmotor(Motorcycle engine) in contrast to RM for Rollermotor (Scooter engine)

EM means Einheitsmotor (Standard Motor)

[Puffs]

Well R1100purist, a bit of apologies on hijacking your thread, but the topic of mixing ratio comes up every now & then, and there are diverging yet strong views. And it was off the radar for a while, and KE-DENG, back it is. If you watched the video I linked to, you have seen one or two smoking MZ's, which probably mixed richer than 1:50. Anyway, do what you like in your TS, 1:50 is the factory recommendation, which I & quite a few others happily ignore. A ratio of 1:40 as the previous owner said is probably a safe choice.

Looking forward to see what happens with your TS - in another thread maybe.

2T oil for chainsaw engines (not the oil for the chainsaw) is generally also good & modern semi synth oil, I too used that once, faute de mieux. As said, I'm currently using an API TC/JASO FD spec semi synth. In the past I also used a fully synth, that's what I actually lost the gudgeon pin bearing with (small end).

My 251 is a UK model, bought in Scotland, with a mile-only counter, and (previously) with the headlight beam pointing left, yet without that mixing cup. But you can premix perfectly without such a mixing cup, you just need to measure the oil volume accurately. I often use a tall 250cc bottle, marked on the outside. You can use (clean) water and a scale to find & mark volumes, at SG=1.00, for instance, a weight of 250g has a volume of 250ml(=cc), etc. Of course you need to use an accurate weight scale.

OK breakwellmz, sorry, my mistake, I thought you said you used to have at least 2 MZ trail bikes, amongst the 5 two stroke MZs you had. I would be interested to see pics of those bikes, not so much pics of fuel caps (aka 'rust buckets', for silly prices).

Guesi, I lost my gudgeon pin bearing (with a needle cage) using the oil pump & a fully synth high quality oil.
A richer premix means more oil precipitates from the mixture and is present in the crankcase & barrel for lubrication. This is why race bikes get a richer mixture, see a previous post. Modern oil does not burn because it does not want to burn, regardless of how much of it there is. It is too stable. If it wanted to burn, it would also burn if there was a little bit more of it, right? And also, I have no carbon issues inside the head, rings, or elsewhere, and yes I replaced the silencer a few years back, but that was because it was rotted away due to salt.
Once again, out of interest: what do you mix? Assuming you pre-mix, of course.

[Guesi]

Hello

I mix about 1: 50 and 1: 70

with semi synthetic 2 stroke oil.

[Puffs]

Thanks for that info, and also for the EM = Einheitsmotor!

Maybe Blurredman was right, maybe it indeed just depends on the application.

[R1100purist]

Guesi and puffs thanks for the lively conversation. I’m hoping this thread can be useful for others searching in the fuel. I understand the normal perils and pitfalls in discussions about oil and oil quantity on forums but I feel this has been a nice conversation among all players.

In the end it sounds like if I’m 50:1 or slightly richer I should be good to go. To that end I found an 8 oz (250ml) nalgene brand container with graduations to accurately mix/carry oil on the road.

I’ll be cleaning up my TS 250 this weekend and I’ll take some photos post clean!

Thanks again all for the responses.

[Blurredman]

An 8oz bottle would be just fine for the 12.5litre/2.7gal tank you have for 50:1

[R1100purist]

Alright, got her cleaned up and did an initial shakedown ride. It was out to the country side and she did fine. Although a little difficult to keep her idling, and after a fast run idle was reluctant to come down.

Additionally there was a little leak from the drain plug that I’m trying to sort out.

[Puffs]

Nice bike!

Check if everything seals well & that it doesn't aspire air bypassing the carb ('false air'), that might cause your idling issues.

[R1100purist]

I checked all the gaskets on the carb and they look good. I feel it has more to do with the ignition advance? Any thoughts?