Good morning
That looks great and a good way to do it.  I have not seen it done by building up such big pieces of missing fins. I have always made replacement fin pieces or had the original broken part to fit back which is difficult to get in there to weld sometimes.

Wish I had seen that years ago.
Great job and worth the time.
Scooter

Good afternoon,
a couple of photos of inside and outside of 762 throttle tube would be much appreciated.  It looks like there might be some piece added inside of it from the parts diagrams.
If I can see photos of a real one I will know enough to decide if I have the ambition to make one.  Each time I make a different spiral, I have to make different tooling or do them by hand.

How the spiral is held on with 763 is the part I do not understand.

Thank you,
Scooter

Good evening,
I have brass brazed them, nickel rod arc welded them and on areas where I cant reach I have metal epoxy glued them on, but that has to be thick enough to hold and you can see it.

There are people that tig with nickel and also mig weld them. 

The problem with brazing is so much heat is needed at one time that a lot of the cylinder is heated up that the uneven heat my be risky for for deformation or cracking. But, I have done a lot of it and am not aware of a problem.

When people tig or mig weld them, they do not preheat, they do bits at a time.

look for videos.

Good luck,
Scooter

Good morning,
I am glad you pointed that out, I did not know that.  Interesting they would change the models so often.
Thank you,
Scooter

Good evening,
I cant tell from your pictures or what you wrote to tell what broke.  Are you able to explain?
I do not know what all type of controls Simplex used, but that sure looks like a Honda spiral control type.
More information will help.
Good luck.
Scooter

Good morning,
Looks like a great find!
Good luck,
Scooter

Good morning,
That is one sharp bike.  Not much beats the joy of bringing old or scrapped stuff back to life.
Good luck,
Scooter