Vaccum advance parts

[corey]

I've taken apart my vaccum advance unit and have deduced that the vaccum diaphragm/canister part is bad. You know, the part with the vaccum line coming into it on one side and the arm coming out the other. It feels like a spring is bent or over sprung inside of it... or something. Either way, it's broken.

Does anyone know if I can repair this item? ...or is it necessary to obtain a new one? ...any ideas where I can get this piece?

[tommystinson]

It's not repairable, at least as I understand it. It's also discontinued, so perhaps someone here has an extra one, or you can try Speed and Sport: www.nosyamaha.com

[TopCatGr58]

I remember seeing one on Ebay a few days ago, but must have scrolled off, don't recall if anyone bid on it, so can't be sure if it'll reappear?

I know cars have vacuum advance units on their distributers, I would think there might be a way to take the old one, and try to match it up, but not how hard it would be to match up the amount of travel it has, as well as how much vacuum is required to cause it to travel. I know there is a spec on how much vacuum is to be applied to cause it to go thru full travel, just don't have my manual handy!
T.C.

[Pat Kelly]

just need the same area of diaphram vs spring pressure, then the right shape of arm and mounting tab location.
simple

[dewibp]

I have a 78 engine in the garage that should have a vacuum advance on it. The question is "will a 78 unit work on a 79 xs11 special"?

[John]

Yes it will work. Bolt it up and go ridin'.