Help with fuel petcock

[scamp62]

ya it seems to be running fine, i thought that "PRI" was primary ?!?!?!

[greenbarn]

Hey Scamp, if you have a way to put vacuum on the petcock, that's the best way to test it to see if it flows in "on" and "res".

A good way to do this is with a mityvac tool...
http://www.amazon.com/Mityvac-MV8000-Automotive-Test-Bleeding/dp/B00265M9SS/ref=sr_1_1?ie=UTF8&qid=1404785694&sr=8-1&keywords=mityvac

also real helpful in bleeding brakes

[gdrudd13]

I did the same thing trying to drain my tank couldn't figure out why, I actually thought the petcock was completely bad. Of course the in tank filter was clogged on mine so it took longer than it should have even with it on prime.

[CDNRatMan]

Right I forgot about that, 

so when the there is no vacuum on the line (such as when the bike is not running) no fuel will come out

I learned this the first winter I owned the bike, I wanted to drain the tank and opened the petcock to run and nothing came out, then tried reserve and again nothing, but when I turned it to prime (old school ) I thought it was like off, but then understood that after a empty tank or running out of fuel that is the way to "prime" it. So it should drain on prime.

the 800 only has one carb.

[gdrudd13]

One thing about the petcock is that it is vacuum actuated, so when the there is no vacuum on the line (such as when the bike is not running) no fuel will come out. It's kind of a failsafe I guess. This is both in the on and reserve settings. so with the gas running out freely on prime, but not on "on" or "reserve", it sounds like it is working correctly.

Does the bike run now? Before you tear stuff apart again, I would hook up the fuel and vacuum lines and see what happens. It would be a good idea to turn it to prime for a couple of seconds before turning it to the "on" position if it has been sitting for a long time.

[CDNRatMan]

  Troll has you on the right path. Check you cap and the vent, unless the fuel has been sitting for a winter or so it should not have varnished.
Your issues are sounding like Driftingirl's and she cleaned her vent and around the fuel cap and it was good to go.

[Troll]

PRI means PRIME, and that's what it's supposed to do. Check the vent in the cap and the vent hose, both could be a source of difficulty

[scamp62]

I was having a problem with keeping my Drifter 800 running, it would just stop running after a minute or two! no sputtering, just off ?!? but after a few moments I could start it ?? I tried it again with the petcock in the reserve position and it ran with no problem (and yes I had a half a tank of gas in it !!) so I decided to rebuild the petcock, I figured that the crappy gas we have now, it was varnished, and clogged with it, after the rebuild I found that when in the "PRI" position fuel ran out freely from the tank (and into my shoe !), I don't remember it doing that ?? is that correct ?? in the reserve and ON position nothing comes out the petcock. So did I do the rebuild right and one last question for today is what is the difference between "PRI" and "ON" ?? call me old school but I'm use to "ON" and "OFF" ! any information would be appreciated !