I need to replace the headset on my 78 Moto La Grande. Can someone tell me what size I need. I will reuse the stock threaded fork.

Thanks

I believe your stem is 22.0, and it'd be best if you bought another typical headset and replaced only the races and bearings, keeping the top cap / nut original. The threaded parts, that is.

?

https://sheldonbrown.com/gloss_ha-i.html#headset

Not sure if your fork is French threaded, something you may want to check. If so, here's Sheldon's page for French bicycles that may be helpful:

https://sheldonbrown.com/velos.html

Thanks. I'm guessing it's french because it has a flat portion on the steerer.

Your options for replacement narrows in that event.

Stronglight still offers a French thread headset in the A-9. I'm not sure of any other manufacturers.

Maybe with luck & patience a NOS one will show up on ebay.

There are a couple here and there on eBay, but Harris sells them for $50. Seems a fair price. Although I may end up changing the entire fork. The top of the steerer tube has some damage and I could not get the headset completely off of it. I may get lucky and find someone with the right die, but maybe not. If I get a new fork, I'll just get one in a more common thread.