Flywheel Removal

Montesa flywheels are fastened onto a tapered shaft.  The woodruff key is only a location device.  It is used for location purposes for ignition timing.  The key does nothing else.  There are 2 flywheel pullers for all vintage Montesa flywheels.  They thread into the flywheel with right hand threads.  The flywheel nut, on the other hand, is a left-hand threaded fastener.  The two sizes are 27mm x 1.25 thread pitch and 30mm x 1.5 thread pitch.  You must have the engine number to order the correct one.  There was a change in at least one model from one to the other during its production.

If you find a part number in a parts book that doesn’t have these numbers then there are super cessions to them.  As a rule, any part number with a D prefix is a 27mm and any part number that is all numbers supercedes to the 30mm one.  Check for prices in the parts listing.

Steps in flywheel removal:

1. Hold the flywheel with some holding device.  If you have an air impact driver then a hand will do.
2. Use a socket wrench.  A 22mm or a 7/8” size will fit.
3. Turn clockwise to remove flywheel nut.  This is a left hand threaded nut.
4. Remove the lock washer.  This is a left-handed lock washer so don’t lose it.
5. Install the appropriate flywheel puller by turning it clockwise and turn it until it bottoms.  Note: This is important.  Any less and the threads will strip on the puller.
6. Fasten the appropriate wrench to the center bolt of the puller.
7. Turn the bolt clockwise until the flywheel pops free.  Here again an air impact driver will do the job quite nicely.  If you are doing it by hand then use about an 18” break-over with ½” drive and a strap wrench to hold the flywheel.
8. This flywheel should torque to 72 lbs. ft. when reassembling.  The factory installation may be a bit tighter.  All of the flywheels I’ve removed from Montesa engines have been done this way.

Heat doesn’t work.  The crankshaft and the flywheel hub are steel.  The metal was cleaned of all oils and contaminates before they were installed and both metals expand at the same rate.  You will likely damage the coils on the stator when you use heat.

Before you reinstall the flywheel you should clean all oils from the taper in the flywheel and on the crankshaft.  Use alcohol or electric contact cleaner.  Do not touch them with your fingers.

USE A 2 OR 3 JAW CLAW DO NOT PULLER, these will destroy the flywheel.

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