Minarelli Flywheel Puller

It's been a while since I've posted, but, I have another question regarding the Minarelli V1 engine. I've got a 1981 Alexander Reynolds EZ Ryder moped, and to make I want to make my own flywheel removal tool....I know they only cost around $20, but, I'm taking machining courses at the local college and I have access to all kinds of stock to make tools from...anyway does anyone know what the specs are on the internal threads of these flywheels?? I'm going to assume that they're metric threads, but does anyone know the "bolt diameter" and the pitch of the threads?

Re: Minarelli Flywheel Puller

Allen Murphy /

Measure the I.D or the threaded hole, which will give you the minor diameter of the hole.

Now--take some modeling clay and press it into the threads , and on the clay, measure the pitch with a metric dial indicator.

Or, easier yet, take a thread gauge and measure the pitch.

Now, go to a copy of Machinery's handbook and look up the depth of the cut, i.e, root depth.

Now the easy part--minor diameter + 2 times root depth = major diameter.

Lathe turn and thread accordingly.

Al Murphy

Re: Minarelli Flywheel Puller

My engine is apart so I went out and beasures the thread.

Using my metric pitch gauge it appears to be 1.0mm/mm pitch.

Doing some rough measurements I would guess that the major diameter is 20mm

You could consult a metric thread table for a 1.0mm pitch to see what the major diameter should be. Or you could machine a blank to see what would just slip in the hole. I measured the hole at .700" (measured twice) which converts to 17.78mm. Start with a 18mm blank and then go from there.

Let us know what you find out.

Re: Minarelli Flywheel Puller

Allen Murphy /

Since the thread is cur at a 60 deg. angle, the pitch is equal to the depth of cut(root depth).

Therefore, 17.70mm + 2 times 1mm = 19.70mm (20mm).

Just get lazy--get a 20 x 1.00mm bolt and go from there!

Al Murphy

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