Modern Vespa

should the woodruft key holds at the end part of the cam's notch/slot?



because when the key was sheared, i found the half part stuck at the middle of the notch/slot (pic below)

It looks like a flywheel taper you are holding. The woodruff key on the flywheel merely aligns the flywheel onto the taper, for ignition timing. It is the taper that holds the flywheel in place. The woodruff key on the flywheel taper can align anywhere on the groove. If it shears, it may migrate anywhere along that groove.

yea i am just worried if my flywheel cam is too long and i use the wrong size

Isn't this part called taper? cmiiw

I'd try that part on the shaft without a key it should get tight on the shaft before it get to the shoulder on that shaft.

I'd be interested in seeing the condition of your flywheel shaft. Your flywheel interior taper looks to be in pretty bad shape. The woodruff key is simply a position indicator. The friction fit between the shaft and the flywheel is what keeps everything together. The video below show how to lap/fix the situation.

the crankshaft taper is not smooth anymore, it has many scratches, so i added a piece/small sheet of soda can in hope it will wrap the shaft taper and hold the flywheel. It really works as temporary solution while in emergency situation at least. I am going to get a new crankshaft anyway.

I am just curious about the woodruff key position when the flywheel inserted, anyway thanks

You're using a soda can? Why not even out the scratches with grinding paste like the video? Using a soda can as a shim does not sound logical.

The woodruff key may or may not fit at the end but it should have the correct width and height to hold the flywheel in one place.

The key's location in it's slot is essentially irrelevant. What you need to do is to lap the two mating surfaces. Without doing this, you will never be able to set the timing. No need for a new crank unless there are other issues.

grinding paste is not a common thing here, and i've never heard that kind of product. But It sounds interesting, i'll try that later

wow never heard that before, i'll try it later. Yes i am sure i have few problems, the nut thread is bad, unbalanced crank, and expanded woodruff key slot. Someone offer to fix those problems by welding and recreating the thread and key slot, but i am not sure it would be good

https://www.amazon.com/Chemico-Valve-Grinding-Paste-Corse/dp/B006ZXZYMA/ref=sr_1_4?keywords=valve+grind+paste&qid=1638535044&sr=8-4