Installing a flywheel

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To install a flywheel, there are a few steps, most of which are self explanatory, but some aren't. There are quite a few ways to do this, but this is exactly how I do it. I don't use a torque wrench, but if you have one, use it.

Make sure you have the necessary tools and parts.

  • Tools
    • Rubber mallet or a piece of rope
    • Socket of the correct size for the nut
    • Ratchet for your socket
  • Parts
    • Flywheel
    • Woodruff key (If your bike uses one)
    • Flywheel nut (and washer if it has one)
    • Tube of toothpaste
    • Container BLUE loctite


  1. Make sure your stator and electronics are tightened down well. You don't want these coming loose.
  2. Insert the woodruff key in the slot on the flywheel.
  3. Smear the shaft with the toothpaste. The toothpaste has a really fine grit in it that helps keep the crank and flywheel located. By doing this, the toothpaste will keep the flywheel from slipping and shearing the key if you don't torque the nut down enough.
  4. Line the flywheel up with the woodruff key and slide it onto the crankshaft.
  5. Place the washer on the shaft, put a drop of loctite on the threads, and then thread on the nut.
  6. There are a few differences here. Most of the time, I take the spark plug wire off, put my socket and ratchet on the nut, tighten it as much as possible, then whack on the end of the ratchet with the rubber mallet. For this trick, the spark plug needs to be in the hole. Alternatively, remove the spark plug and feed a length of rope into the plug hole to work as a piston stop. If you do this, you probably can get away without using the mallet. I usually still use it though.
  7. Set the timing as per Fred's Guide or Ignition timing

The real trick to this is to use the toothpaste on the shaft, then use loctite on the threads to keep everything from slipping. --Strongar 21:44, 26 December 2009 (EST)