Home Forums Tech Talk Repairing brushes in Leopard starter

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    • #45465
      Samir Shah
      Participant

      Hi. I’m new to this forum, and to 2 cycles. My son is now racing in Leopard/Parilla Jr, after 6 years in 4 cycles.

      I recently bought a 2nd 2007 Leopard motor as a backup, which was push start, and converted it to key start by changing the stator, stator rotor, and coil. I also had to drill and tap a hole on the chain cover for the new coil.

      When I tried to start it, I discovered that the starter was dead too, and ordered the new brushes for it. While waiting for the parts, I opened up the starter.

      The problem was that the positive braided wire, with brush attached, had broken off from ‘tin plate terminal’. I tinned a 12 gauge wire, soldered it to the terminal, bent it at a right angle, and soldered to the braid. This will give the braid a few more mm of extension too. Put it all back together, and it works!

      I’m not sure how long it will last, and I don’t know if the current flowing through it is likely to heat and melt the solder and disconnect the repair.

      However, I wanted to post to let people know that this can be repaired without a $25-30 brush kit (which is a ridiculous price). I’m going to try and hunt down a cheaper substitute that might work.

      Sorry, I did not think to take pictures of the repair.

      Regards, Samir.

       

    • #45843
      William Martin
      Participant

      If it gets too hot and un-solders the wire, try silver solder, or any Rohs-compliant solder for printed circuit boards, they also have higher melting temperature than the “traditional” lead-tin solders.

       

    • #45845
      Samir Shah
      Participant

      Thanks. Yes, I used the silver based solder that I use for my audio stuff. It takes about 750-800 degrees to solder anything 18g or thicker, vs 400 for the old leaded stuff.

      This is on my backup engine, so I won’t know for a few months how well this worked.

    • #56328
      Hans Mattes
      Participant

      It seems that the lead on the ground brush of the Leopard starter is prone to breaking.  Mine recently broke and the box of parts I got with the used kart had several ground brushes with broken leads as well as a starter with a broken lead on the ground brush.  It appears that the previous owner had repaired some and had applied silicone (RTV) to all the brush leads.  He may have believed that vibration was causing fatigue failure.  But the silicone didn’t seem to end the problems.  Are there any other theories (or even facts) about the cause of failures?  One possibility might be that inadvertently hitting the green “start” button while the engine is running could cause the Bendix to engage and spin up the starter to a point where the brush is damaged.  I know that there’s a similar issue in motorcycle-engined racecars (I have one).  If  the car spins and travels backwards for any distance before the clutch is depressed, it kills the starter (which has a one-way sprag clutch rather than a Bendix).  The starter failure there often involves killing the brush assembly (ask me how I know).  I’m considering putting a flip-up cover over the Leopard’s “start” button to prevent accidental engagement.  Any suggestions?  Thoughts?

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