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Removing rev limiter on small two stroke

  1. Apr 13, 2005 #1
    I have a zenoah g62pu engine on a scooter, about 62cc's. It has a rev limiter in the coil set at 12,500 i think. Id like to know how you could remove this. I have heard rumors of burning it out somehow, but no facts on it. It is a very small unit, maybe 1 square inch with a wire that goes right to the spark plug.
  2. jcsd
  3. Apr 14, 2005 #2


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    A rev limiter can be implemented different ways that could be simple or complex to circumvent.

    Does the motor start cutting out when it reaches the rev limiter? Like whirrrrr rrrrr rrrr rrr rrrr rrrr rrr type running? If so this MAY be easy to circumvent but could still be complex because while there are popular methods a lot of different ones could be used. Without a schematic you'd have to test it and figure out what method it uses.

    A lot of times the physical construction of the engine limits revs because it runs out of power extremely quickly near the top. Used on inexpensive edge trimmers and leaf blowers, but applicable to any two stroke.

    As you increase the revs the stress on the connecting rod rises sharply by the square of the increase. Add 10% more revs and you have 20% more stress, 20% more revs and 44% more stress. How long can it handle that before failure?
  4. Apr 14, 2005 #3
    im not extremely concerned with the connecting rod, the engine puts out maybe 7 or 8 hp tops, 5 stock. this engine, and all of zenoah engines that im aware of, originally came with locked carburetor settings. currently the engines come with a coil based rev limiter. other people buy different limiters for other zenoah engines and retime the flywheel to allow for the engine to rev to 20k or so. so it is coil based, schematics...i dont know ill try, does anyone know how to get around it?
  5. Apr 14, 2005 #4


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    If the coil itself was designed to stop delivering good spark above that RPM then you will need a new coil. OEM puts reliability above performance, no one makes money doing warranty work and earning a reputation of engines that blow up. So aftermarket may be the only choice.

    On the late 60s Boss 302 Mustang for example, the rev limiter simply cut off the ignition power source by interferring with the points/coil. It was a simple one wire to cut to eliminate it, as if the engineers had acknowledged that for warranty purposes it had to remain intact. But for owners who bought the car to use it, they cut the wire as soon as they could and they both win since the customer gets perf and Ford didn't have to warranty it.

    Altering the ignition timing makes sense too.

    If the connecting rod goes there isn't much of a point to the rest.
  6. Apr 14, 2005 #5
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