We have been talking about ignition systems and their repair, but one important component is flywheel removal. Especially if you have an engine with points. Typically the points are underneath the flywheel, and when they go bad, the flywheel must be removed.
You will discover that flywheels have illusive retention devices, in particular the rapid rewind systems that include ball bearings.
You will also discover that once you figure out how to remove the “rapid rewind cog system” that the flywheel is fixed pretty hard on the crank shaft.
This article is about:
- How to first of all remove the “rapid rewind cog system.”
- Secondly how to remove the stubborn flywheel
- And finally how to put it all back together again.
It should be noted that the flywheel has fins on it. If any of these fins become broken, the engine will become out of balance and vibrate intensely. If the fins are broken, the flywheel is junk, so be very careful around the fins.
To remove the “rapid rewind cog” use a pipe wrench and a screw driver. The pipe wrench is put on the “rapid rewind cog” and the screw driver is inserted in between the cast iron fins. (Note: there are aluminum fins, stay away from them, they will break)
Rotate the crank shaft so that the screw driver is pressed against an immovable object. Another method which is more forgiving, is to wedge a piece of wood (this works best when the engine is mounted to the engine mounts on the go kart) under the flywheel. This acts like a wedge brake.
Gently press down on the pipe wrench. Excessive force is not needed here. The “rapid rewind cog” generally comes off rather easily then.
A note with respect to the “rewind cog”: unless you like chasing ball bearings all over the floor, keep in mind that typically a screen covers the rewind. Remove the screen, BUT put the retention screws back in place right away. This makes the “rewind cog” stay together, and also be accessible to the pipe wrench.
Next the flywheel is stuck on the crank shaft with a press fit. Actually the flywheel is press fit using a cone shaft aperture on the crankshaft. The object is to “pop” the press fit. To do this generally a shock needs to be introduced into the system.
There are two methods that work best. First shock the end of the crank shaft with a very hard piece of wood and a mallet. Note: do not use steel on steel, the end of the crank shaft will become mushroomed over and become unusable. Repair is usually not doable.
There are tools available that you put on the end of the crankshaft, but even they can damage the crankshaft. So be careful to use minimal blows on the crank. And in case I did not make myself clear, the blows are normal, or perpendicular, or axial to the crankshaft, not to the side of the crank, but to the end of it.
Sometimes that does not work. If the engine has been sitting around for years, or is over 10 years old, the crank may have rusted partially to the flywheel.
Use a little penetrating oil at the flywheel, crank interface.
Then pry the back of the flywheel, very gently, and evenly with a flat head screw driver, or even a prybar. Very light action is needed. If you are reefing on the screw driver, there is something wrong. (something else is holding the flywheel on!)
The flywheel should “pop” off right away, so be sure to catch it before it flies off and falls on the floor. I suggest having a catch system such as rags or cardboard.
To reinstall the flywheel put it back together the same way it came apart. Use the pipe wrench and the screw driver method to tighten the “rewind cog.”
Again, do not over tighten the “rewind cog.” Also take note that the washer was put back in place.
Just as a side note, the only real reason a flywheel should be removed on modern magneto style engines is if the key way sheared. If the key way sheared you should be looking at other areas on the engine for damage…
About the Author: wahm