Premix??

Forums Technical Two Stroke: Help needed Premix??

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    • #4910
      nigelphoto
      Participant

      I’m an ‘old’ newbie (joined MZ Riders today!) and just bought my second MZ, oh in about 35 years! In the ’70’s I had bright yellow Supa 5, and I recently bought a TS125 ‘doer-upper’. I have a question about the premix ratio. The handbook which came with my ’86 TS125 says 50:1, but the technical specs on another Forum says 33:1. My TS needs quite a lot of attention before I try to fire it up, but I’d be most grateful if someone could enlighten me on the premix when it is ready to go.

    • #4911
      Anonymous
      Inactive

      I’m no MZ expert, and mine (supa 5) should a runner in about a week. I’m going to run it at 33:1 richer than recommended as I have seen some wear on the little end and gudgeon pin when I have rebuilt it. More oil can’t be a bad idea, can it?
      Keep us informed, this site needs more traffic
      Jon

    • #4912
      Brian Thurlow
      Participant

      I think if the conrod has a needle roller little end bearing you can use a 50:1 mix, earlier model’s had a plain little end bush and needed a 33:1 mix.

      Using a 33:1 mix won’t harm in a 50:1 motor.

    • #4914
      Anonymous
      Inactive

      Mine is a needle roller, which I have replaced, along with the gudgeon pin as a precaution. Still intending to use 33:1
      Thanks
      Jon

    • #4915
      nigelphoto
      Participant

      Thanks very much for the replies – I don’t know whether my 1986 TS125 has a roller or plain bush little end as I haven’t taken it to bits yet. As a matter of interest wouldn’t 33/1 cause plug oiling in a 50/1 engine?

    • #4918
      Anonymous
      Inactive

      that’s the only foreseeable downside I can see also.
      Will let you know when mine’s a goer!
      Jon

    • #4919
      Anonymous
      Inactive

      you should bare in mind that the more 2 stroke oil you put in the mix the weaker the fuel/air
      mixture will be, it could lead to pre-ignition (pinking) and the engine will run hotter.

      Ian

    • #4945
      Markus Ensslin
      Participant

      hi –
      1:50 on mineral 2stroke-oil will do…
      i run a 1969 250 engine on 1:50 mineral, too. no problems whatsoever…

      g max ~:)

    • #4946
      Anonymous
      Inactive

      excellent thanks, bit rusty on premix, its been a while
      Jon

    • #4947
      nigelphoto
      Participant

      Thank you Ian and Markus, both answers make sense so I will try 50:1 and see how it goes. I’m waiting for a new petcock from the MZ Shop to arrive and I should be ready to fire ‘er up. The previous owner had left the TS in the street for 6 months without starting it up and the inside of the tank had a lot of rust in it, the zinc body of the petrol tap also having being badly attacked; thats unfortunately what we increasingly face as the % of bioethanol they are now polluting our petrol with goes up!

    • #5035
      Stuart Patterson
      Participant

      I have been running mz’s for years initially ts250 at 50:1 but did have both crank and main bearing failure at different times
      For the last 3 years I have run a ts125 I have a wilf green owners handbook that says with the later motors from about 75/76 50:1 is right after being run in at 33:1
      I use the cheapest 2t availible (carplan @ 3.50 ish per litre ) at 33:1 and it runs sweet as a nut
      Remember 50:1 is 2% oil and 33/1 is 3% thats only 1% less petrol (bugger all difference) use the good petrol the higher octane will outwiegh the less petrol
      The measure in the tank is for 1 imperial gallon at 50:1 or 4.5 litres so on that basis 1 measure for 3 litres or 2 for 6 litres or even 3 measures for 9 litres will give you 33:1 🙂 4 scoops to a full tank from reserve will give you somthing like 30:1 and it will still run sweet
      Good luck and enjoy your bike

    • #5060
      Paul Ashton
      Participant

      I run my ETZ engine on 34:1. That is 34ml of fuel to 1 of 2 stroke oil. That equates to 145ml of oil in 5 litres. Ian is correct about leaner mixes, but I run the engine fairly hard, so I run it rich.

    • #5061
      Paul Ashton
      Participant

      That is to say set the needle height higher.

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