ES250/2 premix

[Blurredman]

If ES250's were originally supposed to have a pre-mix of 33:1, then they would have been jetted accordingly.

Then as the TS250 came out, more stringent emission laws came from the localised government of East Germany, the TS250 had to be limited to a 50:1 (officially). The carburettors were changed accordingly. Don't forget though, that bikes in that region didn't cover the same amount of ground that they now do. And even at the time, In the UK it was common for TS250's that had been used constantly as despatch bikes to have seized owing to the constant 70mph motorway speeds back and forth about the country. The Germans didn't seem to have such business enterprises, if they did they were not inter-city.

I always found it odd how Eastern Germany decided for emission standards, where as Russia didn't, and still advocated 25:1, they still produce 2t motorcycles now.


Back to the point though, seeing as ES's are carburettored for 33:1 ratio, then the previous point about ratios being incorrect in the combustion chamber is besides the point.

Regardless, coming back to TS250 being set up for 50:1, and then running on 30:1 is also somewhat moot. The difference in the amount of fuel going into the engine is about 3% I believe, that is for the whole tank's worth, just 20cl. Practically nothing.

[stogadog]

From what I know about the difference in ratios between the ES and Supa5 ; they are different because the ES's main bearings are lubricated by the petroil mixture in the crankcase (in board of the crank seals) and the Supa5 main bearings are lubricated by the gear box oil. This is why the crank case halves don't need to be separated to change seals on a Supa5 .
I do think though that it isn't that important providing there is roughly the correct of oil - considering they are such unstressed engines and the fact that oil is MUCH better than it was (especially behind the iron curtain!).

[breakwellmz]

That`ll be it then!

I didn`t realise that.The mains being running in oil sounds preferable to me though,if it`s decent oil and is changed regularly.

Modern two stroke oil can be used more sparingly than earlier versions in my experience,especially`synthetics`.

[arry_b]

The mains being running in oil sounds preferable to me though,if it`s decent oil and is changed regularly.

...and there's the problem, that's a big "if".

In service, lubing the mains with premix proved more reliable than relying on someone checking / changing their gear oil often enough. The 250's aren't exactly immune to getting water in the gear oil (through the clutch cable), and the watery emulsion killed the main bearings in short order.

[therealche]

From what I know about the difference in ratios between the ES and Supa5 ; they are different because the ES's main bearings are lubricated by the petroil mixture in the crankcase (in board of the crank seals) and the Supa5 main bearings are lubricated by the gear box oil. This is why the crank case halves don't need to be separated to change seals on a Supa5 .
I do think though that it isn't that important providing there is roughly the correct of oil - considering they are such unstressed engines and the fact that oil is MUCH better than it was (especially behind the iron curtain!).

Think you have that back to front !

ES has mains lubricated by gearbox oil, the Supa5 has them lubricated by petroil. On the Supa 5 the oil seals are outboard of the bearings, between the gearbox oil and the bearings. In the ES engine the oil seals are between the crank and the bearing, so the lubrication of the mains is by gearbox oil.

[stogadog]

Actually yes that rings a bell. I stand corrected!