Dennis Stubblefield lists MP#7 as the correct internal rotor Yamaha puller for the early MX/YZ.

 



.

 

Just to confuse things i measured mine & puller is 19.83 OD & inner rotor 18.42 ID. First time i've ever used digital verniers recently given to me by my old workshop foreman who's health is failing. Brand new out of the box. Still like my old dial type though. Check my rotor number & is the same M100-8 or whatever OP was back a page.

Doesn't confuse things...  verifies. 

Almost certainly the recess in the motion pro is not deep enough.

Yep must be easy enough to verify so hopefully will measure depth & come back. Be unusual to make a very shallow internal depth puller, depending on what model & how much crank sticks out i guess. Anyway!!.

Guessing I'd say Motion Pro has about a half inch recess and need to be 3/4"...  hopefully we'll find out. 

Thread is definitely 20mm x 1.5 so if recess is deep enough then maybe something messed up threads in rotor?

Ok guys...found out the issue.
The Motion Pro puller interior depth is 30mm. Plenty of depth for a good bite for the threads.
But...at some point the starting threads on the rotor have been impacted / rubbed / deformed enough to not allow the puller to thread 'straight on'.
I can hand start the Motion Pro on and it binds immediately.
In spinning the crank manually I detect definite run out on the puller. And with a run out condition, I feel the puller will cross thread if forced.
It will be difficult to correct what ever small 'bend' in the starting threads there is with the rotor installed.
And thanks to you guys, I can see the Motion Pro M20x1.5mm is the correct thread.
I can gently attempt a 3 jaw puller but really hate to do it but it will be the only way to chase the threads for correction.
Any thoughts??



 

Oh bugger. I'd be tempted to force it in a bit to see what happens--until its too late. If ya lucky it might not be super tight but if you 'have' to use the 3 jaw can you get a real heavy steel plate & shape it to similar shape to the rotor then slot it to go over the shaft behind the rotor so it'll pull from the center which will be steel with the alloy & magnets & spread the load up behind. Except i guess slotting it will take its strength away somewhat.

Not sure if tapering off the first few threads at an angle would help rather than just coming to a stop, it might creep on resisting but find the straight ones--or not. I also put a grind mark on the thread longways to pickup any chewed metal. Did this on my 27x1mm flywheel tool to fix a damaged flywheel thread. Different situation but similar.

Now there's an idea.
I need a cast iron piece to make a 'behind the rotor' adapter. It would resist deflection / bend.
Maybe 1/4" plate could work too.
Use a 2 jaw puller and 'hook' it in the slots made in the adapter legs.
Great idea.
I'll start making this piece and update progress.
Here's a drawing of what I see....