ETZ 251 Carb swap?

Forums Technical Two Stroke: Help needed ETZ 251 Carb swap?

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    • #10096
      Andrew Moore

      Just completed a first tour on my re-built ’94 ETZ 251, in Scotland.
      Enjoyed the ride, but the bike is definitely down on power for a 250. Starts well, but erratic tick-over and lack of mid & top end are leading me to question the new Chinese Bing copy carb that was on this non-runner when I bought it. (Suspicions were aroused when I spotted that the word ‘Choke’ was spelt with a ‘D’ on the lever!). Have tried the needle in various positions – it’s now in the lowest groove (richest setting) which did improve matters, giving the plug a tanned colour. No jet sizes marked on any of the jets inside, leaving me with the feeling that this is a carb with little scope for improvement.
      There seems to be good results from people having used a Mikuni VM28 or VM30 in place of original MZ BVF instrument.

      Has anyone any experience of this, either using a Mikuni from a breaker, or brand new from Allens or similar? Is the Mukuni a better bet than the Bing which seems to have been an OEM fitment on certain models?

      Any pearls of wisdom would be appreciated.

      Drew Moore

    • #10097
      Craig Smithson

      Phone martin at burwins excellent chap you’ll need the carb and machined inlet plus rubber collar he will know he will be the best bet use him for everything

    • #10131
      A A A Dummy

      Yes Martin at Burwins mikuni conversion transformed my super 5 into a delight lovely low bing ding ding tick over and no hunting on over run also 85 mpg on last top up. Air box hose should be treated to plenty of boiling water and levered on using tea spoons to save machining the bell mouth down but once fitted you will not look back. Starting on mine is 2 prods to prime and 1 kick to start. Most other conversions cost less but this is the by a country mile . My friend David Ley zed riders and kent section British 2 stroke club has done the same and is over the moon with the ease of starting and smooth running. try it. A quarter turn on the mixture screw either way is all you will need .
      Simon Rotgans

    • #10153
      Craig Smithson

      Totally agree transform bike from 20 kicks to 2-3 plus more low down power now ticks over and no hunting on the over run

    • #10824
      Andrew Moore

      Much belated thanks to Craig & Simon – really appreciate your advice chaps – will be getting in touch with Martin @ Burwins shortly.


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