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• Top End

  Top End Related
  56 Topics

  678 Posts

  S

  I already ordered what I thought was a full set and everything else is the right colour but the cowl was listed as blue instead of sky blue, it looked the right colour in the picture but it was taken in a shadow so was hard to tell and when it has arrived it doesn't match any yamaha colours, not sky blue, not endurance blue and not deep purpleish metallic blue so now I'm trying to sort it out with them but looking for a genuine one incase they can't get one

• Bottom End

  Bottom End Related
  7 Topics

  42 Posts

  H

  Sorry for commenting on a 3 year old thread, but I have worked a little with balance shafts on humongous machinery and wanted to post a little for posterior knowledge.

  A single balance shaft on a single-cylinder doesn't really do much. It mostly just phase-shifts the vibrations so they go in another direction. Back and forth instead of up and down, like.

  Dual balance shafts is another thing. They cooperate in the right direction, and counteract each other in between - and if you put them slightly offset each other vertically they can even mitigate some rotational moment.

  But balance shafts also have another interesting effect - they can reduce the bearing load. There are actually two different optimums - one which gives the least vibrations but a bit higher bearing load, and another that is the opposite.

  So when I see that small engines have a single balance shaft, I usually assume it is to allow it to manage high revs by means of lowering bearing forces rather than reducing unpleasant vibrations.

  There was a bike back in the 90's(?) - some european single-cylinder 2-stroke 250 cc enduro (cross?) - that had a balance shaft and managed to output 70+ hp when all the balance-shaft-less big-brand competitors only gave 55 hp or so. Because it revved to like 12000 when the others quit at 9000 or whatever.

• Carburetor

  Carburetor Related
  96 Topics

  953 Posts

  M

  Maybe it's from the 3ET DT200R,has the same carb as the DT125R but uses different numbering in jets, the main is 150 but is not smaller than the 210 of the DT125R.

• Derestricting

  Return the bike to how it was intended to be!
  24 Topics

  383 Posts

  H

  @Hark_Ptooie I found with the Tecno expansion chamber (basically identical to the Athena) it fitted a lot easier using the genuine Yamaha rubber grommet and spacer on the upper mount. The ID of the spacer is quite large and allows a little more movement to line it up than the grommet/spacer supplied..