convert frame mounted petcock for no vacuum

[12thmonkey]

i took my petcock apart just now, and i think i have a new problem. This was all there was when i took it apart:


It seems i don't have the little nylon cone-shaped piece (the middle dot in Kerry's annotated Jenya picture). Any ideas of why it wouldn't be there, or what i can do? Anybody have a spare one laying around? Also, instead of plugging the hole from the inside (lefthand dot in the pic), could you just plug it from the outside, at the flange where the vacuum hose is supposed to connect?

[Jenya]

1) You do have the cone. You just haven't finished taking everything apart.  It is on the other side of the main body piece on your picture under the knob.
You would need to remove a metal clip that has "FUEL" "PRI" "RES" imprints on it by flexing it and pulling it off the tabs on the petcock's body.
http://culbertfamily.com/jenya/gs500/petck_finished.jpg
There will be a small spring under the knob, so watch out for it and don't loose it. Once you remove the knob, the plastic cone will be inside.

2) Yep, you could plug the vacuum port from the outside as well. If I had to think hard of the reason doing it one way and not another, I'd say that doing it on the inside ensures that all the fuel flows in and out, whereas plugging it on the outside may leave a bit of a space for the fuel to sit in permently and potentially turning into a gunk.

Jenya

[12thmonkey]

Yeah, it seemed like it had to come apart more than that. 

Anyway, i finished the modification last week, and just now had a chance to reinstall it (we've had company). So, i reconnect all the fuel lines, and block off the vacuum line from the carb. When i opened up the tank-mounted petcock, gas started dripping out of the front of the frame-mounted petcock, from the knob. i unclipped the knob, and it seems like the o-ring is the obvious culprit. Does anyone know what size it is? Is this something that an auto parts store should have in stock? Is there anything i could've done while reassembling that would've prevented it from sealing?

[coll0412]

There is actually a really easy way to do exactly what you describe without having use JB weld.

THe metal bracket on the front of the petcock that has the words PRI-RES-ON stamped on is held on by a clip type mechanism on both the top and bottom. Underneath is the blue plastic valve(its the yellow plastic peice in the above picture), what you have to do is rotate the valve from whatever postion 180 degrees, then reinstall the stamped metal peice on it also 180 degrees. Take care to ensure that the selecting lever is also turned 180 degrees.

THe result causes the ON postion that it points to,  to become RES

THe selecter lever pointing to RES postion becomes ON

and Prime becomes effecively OFF.

And the coolest thing about it all is the fact that it requires no vacuum to operate, you still may want to plug the port on the carb if the diagphram is leaking to prevent it from leaking.

[Kerry]

Care to repeat that magic trick a little more slowly, and with pics so we can make sure you're not cheating? 

Thanks for posting an alternative method.  Variety is the spice of life, and having more than one choice is almost always a good thing.

[12thmonkey]

Ooohhhhh...so now ya tell me!!! 











Thanks. i guess i'll try that with my next GS...(which is actually becoming a real, impending possibility).

[Jenya]

Yeah,

I see that! Basically, both RES and ON will flow through PRI bypass. Certainly worth of a try. I remember now looking at it and even blowing air with my lungs through it, becuase PRI bypass is of the smaller diameter than main fuel path. I decided to go with JB WELD solution, becuase I remember reading people saying that GS has too much plumbing and even installing larger ID fuel hoses to increase throughput to cure fuel starvation. I though that having to go through a smaller PRI hole may defeat the whole purpose. However, I think it totally worth of trying considering that there is neither cost nor effort.

Jenya

[Queso]

So leaving the petcock on PRI is effectively the same as this JB weld mod thing? Cuz I still have the fuel starvation issue at freeway speeds with gas in the tank and the petcock on PRI... But if I do the alternate method, will that be as effective as the JB weld version? I haven't had a chance to try this yet... Been busy moving. I don't have internet in my new place yet, either, so it might be a while before I can reply... I'm at starbucks at the moment... Freaking "hotspot" ripoffs... argh..

[Jenya]

Runnign in PRI is not exactly the same as JBWeld mod, because PRI bypass passage is of a narrower diameter than normal fuel flow path. And, if I understand it correctly, the alternative mod of simply flipping the cone has the same drawback of running the fuel via a narrower PRI passage.

[JerGStwinguy]

Has anyone just bought a new petcock and have that work?

[galahs]

Buying a new petcock would work 



Do the 2004+ petcocks fit the older bikes?
If so I'd get one of them. Much better design.

[NiceGuysFinishLast]

'04+ petcocks use different sized vacuum line to go to the carbs.

[dgyver]

They also mount differently.

[rnicholas]

I finally did this mod and wanted to say thanks for the great detailed instructions.  Without the pics this would've been impossible.  Bike works great and no leaks (after I made a crafty little new gasket). 

Great example of the sharing of knowledge on the board.

thanks again.

[reload]

so i'm doing this mod now and realized that JB weld dissolves in ethanol.  gas in the US is E10, at least, so i was wondering if anyone has had problems since they did this mod.

whats the longest this mod has held up?

[reload]

bump. anyone?

[ben2go]

Bump.Is the original poster around to fix the pics for this thread?Please.