How to derestrict a 4 stroke

Written by samuel hamilton
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How to derestrict a 4 stroke
Derestricting your four-stroke scooter requires you to remove bolts and washers from your scooter such as these. (stainless steel image by Tom Oliveira from

Four-stroke scooters provide an efficient and enjoyable mode of transportation. Unfortunately they aren't very fast and driving them on the road with much larger and faster vehicles can be scary. You can improve the overall top speed of your four-stroke scooter by derestricting it. Derestricting your four-stroke scooter requires you to remove a small washer from the pulley system which transfers energy produced by the engine into the wheels. Removing this washer requires minimal mechanical know-how and few tools.

Skill level:

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Things you need

  • Socket wrench
  • Impact wrench
  • Strap wrench

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  1. 1

    Disengage the kickstart from the variator system. The kickstart is attached to the variator system by a small pin which must be loosened with a socket wrench and then pulled out. Pulling the pin out will enable you to remove the kickstart.

  2. 2

    Access the variator system. On some four-stroke scooters, this will require you to remove both the intake case and the variator system cover. In other four-stroke scooters, you will only need to remove the variator system cover. Both the intake case the variator system cover are held in place by bolts that can be removed with a standard socket wrench.

  3. 3

    Detach the front pulley wheel in the variator system with either an impact wrench or a strap wrench and a socket wrench. Simply activate the impact wrench over the bolt if you have an impact wrench. Secure the wheel with a strap wrench and unscrew the bolt with a socket wrench if you do not have an impact wrench.

  4. 4

    Remove the small washer located around the front pulley rod that was revealed when you removed the front pulley wheel. This washer restricts the variator system, limiting the performance of your four-stroke scooter.

  5. 5

    Replace the front pulley wheel. Ensure that all mechanical components are attached exactly as they were when you removed them.

  6. 6

    Put the variator case lid and intake case back on.

  7. 7

    Reattach the kickstart to the side of your four-stroke scooter.

Tips and warnings

  • You may need to register your scooter upon removing the restricting washer if your scooter become capable of travelling over the legal speed limit assigned to its specific class. For example, in most states, 50CC scooters cannot travel faster than 30mph.

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