TS250/1 Mikuni Carb

Forums Technical Two Stroke: Help needed TS250/1 Mikuni Carb

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    • #4047
      John Walsh

      hi, i have a Mikuni VM28 Carb which i am planning to fit to my TS250/1.
      Does anyone know the correct jet sizes?
      (main jet, jet needle, needle jet, pilot jet and throttle slide)

    • #4048
      MZR editor

      This should do the trick:

      140 main, N-8 or P-5 needle jet, 5F3 needle on second notch, 40 pilot jet, 2.5 slide

      No idea where you can get them before you ask!

    • #4060
      ‘AAA Dummy

      TS250/1 Carb.
      Try Allens Carbs, Bingham, Notts. Tel:- 01949-836733

    • #4195

      Hi John,
      I am interested in how the carb conversion goes – are there any sleeves need making up, and what’s the difference in the way the bike runs. Be great if you would post up the results when done. Hows it going?

    • #4236
      John Walsh

      Hi, thank you very much to everyone you responded to my request.
      I was given the mikuni carb by an engineer who made two sleeves on a lathe to suit the inlet manifold and the airbox rubber hose.
      I spoke to Allens Carbs who said that mikuni have two branches to their business. “Original equipmnet” and “after market” and often the after market jets are incompatible with original equipment carbs which is what i think i have.
      I not going purchase jets etc to find that they are unsuitable for my carb so have put the modification on hold for the moment. regards, John

    • #4305
      Peter Fielding

      Hi John,

      I found that searching on ebay I was able to find alternative main jets for my VM28 Mikuni (no idea what it came from). There were two types commonly available but taking the old one out I was able to clearly identify the type I needed. I have the carb fitted to a Supa5 engine in my ES250 and it works well but perhaps a tad thirstier than the original BVF with the settings it came with. I have just dropped the main jet from 140 to 135.

      Incidentally, I have found two things which may be of general interest. Firstly if you saw off the clamp on the MZ manifold and file the stub round, you can use a piece of radiator hose to link carb to manifold.have doen this for my ES250 and for a supa5 manifold. Makes switching carbs a lot easier and no air leaks. Secondly, the ETZ125 hose from carb to air box has a smaller diameter suitable for the Mikuni and is a straight swap.These two mods avoid the need to make up sleeves.

      Hope that helps.


    • #4367

      I have been considering going the Mikuni way, but is it really worth the bother and expense? The original carb on my 1978 Supa 5 is corroded inside and has a few battle scars when accidently dropped off the work bench? The carb body was knocked out of true but after a few hours careful work I got the slide working smoothly and all things seem in order. Unfortunately as a newbie to MZ’s I have no experience of these engines but it certainly runs OK. Starting from cold is reasonable providing I follow the “code” but slow speed running is a bit rough but reliable. Phil Speakman has replacement carbs manufactured by IFA. Has anyone any comments on these?


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