Random Questions

[hoppy1]

Bung moves smoothly, nothing is broken, the knob turns it nicely. Goes from 'reserve' to 'on' properly, prime just does nothing. It can function with a vacuum in prime. I have looked at this thing for hours, there is no bypass hole, the only way for fuel to get through the plastic bung and out of the brass hose barb is by flowing through the orifice which is regulated by vacuum. There must be some mechanical means by which the diaphram's plunger is pushed back when the unit is put ino prime.

There has to be at least 2 holes in the body to allow fuel to flow to the handle/bung part. Remove the diaphram and remove the lever from the body. See if there are holes in the body. Remove the filter screen and spray some carb cleaner or air from the top of the body to see if the passages are open. Also look at the lever and plastic bung to see if there are holes in them. By the way, you said there was a spring missing, where did you put that spring?? Hang in there, we'll figure this out!

[surveywaters]

The fuel flows fine. There are two holes in the main casting of the petcock, one from the main pickup (on) and one from the reserve pickup. Both flow fine and align, when selected, with corresponding holes in the bung. At which point the fuel flows through the bung and passes the orifice which is regulated via the vacuum/spring. I placed a spring on the vacuum side of the plunger between the diaphram and the diaphram cover. Keep in mind the 1980 petcock is very different than the '81-'83

[surveywaters]

I just read a thread by someone with a similar problem, they mentioned a spring like piece bent near a 90 that goes between the plastic bung and the diaphram plunger. The small tab inside the bung actuates this part pushing on the plunger. If this is correct, I need an image or better yet, a fiche.

[hoppy1]

I just read a thread by someone with a similar problem, they mentioned a spring like piece bent near a 90 that goes between the plastic bung and the diaphram plunger. The small tab inside the bung actuates this part pushing on the plunger. If this is correct, I need an image or better yet, a fiche.

That makes sense, you would need a lever or cam of some sort to push open the plunger. I haven't found an exploded pic of your petcock yet. I have a friend who has an 82 GS650L that has that same petcock, but his is working fine. Too bad we couldn't take it apart to see whats up.