Changing Crankcase Seals with Engine in Frame

Forums Technical Two Stroke: Help needed Changing Crankcase Seals with Engine in Frame

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    • #10149
      Robert Brickwood

      Hello fellow MZ Riders,

      I am in the process of resurrecting a TS250/1 that has been dormant for 14 years. Went through all the usual processes and it fired up no problem. The bike however has excessive white smoke from exhaust. I will take it out for a run but assuming the worst and the crank seals have gone, i have two questions

      Question 1. Is it possible to replace the crank seals with the engine in the bike? Looking at the totally inadequate Haynes manual i have, it appears possible to remove the dynamo on the offside and the clutch etc on the nearside to reveal the oil seals retained by circlips.

      Question 2. If it is possible, for those who have achieved replacing the seals without removing the engine, do they have any hints/tips learned from experience.

      Footnote. The bike starts and revs very well. I have done all the brakes, tyres, electrics etc. and it has historic vehicle status so am hoping to avoid an engine strip as i want to ride it. To confirm whether the crank seals are blown i am hunting around for a suitable child’s balloon to put over the gearbox filler/vent to try to ascertain whether the crank is pressurising the gearbox via the seals.

      Any helpful advice gratefully received



    • #10150
      Daniel Rodd

      yes its pretty easy,take the clutch and rotor off,i use a small self tapper screwed gently into the old seal then pull out with pliers.

      • #10524
        Robert Brickwood

        Thank you. Yes it was easy and thank you for the tip with the self tappers. Computer probs meant i could not reply earlier. Thanks again

    • #10175
      Mark Kenworthy

      Hi Robert,

      i replaced the seals on my super5 with the engine in the frame a couple of months ago, and have replaced the clutch and dynamo a few times before.

      There are a few things to look out for before you start, which may prevent the bike being listed on ebay as spares or repair sometime later.

      if you are still needing info you can give me a call on 07813 636428 after 7pm or weekends

      kind regards

      • #10525
        Robert Brickwood

        Thank you for your offer of help. I managed to do the job in June with no problems. Late reply to you due to computer problems. Thanks again

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