How to tell if a petcock is bad?

[Tombstones81]

sry how this is posted. on phone at work.   ON bogs & stalls RES doesnt. full tank. no clogs. pinches or leaks.  is there an easy way to just take it off & check it somehow so i dont waste money on a new one if the petcock is fine.  sry for the clump. phone sux

[Tombstones81]

okay, home now so I can post properly.

Eliminating ALL possible problems I can with this wretched bike. haha

New jets inc
Going to another hardware store tomorrow to get those tiny O gaskets and the other sizes I was asked to get, if they are different. (forgot to take them with me this morning and got ones for 50 cents a pop that were just a Tad bit too big)
Going to get all new hoses if I can.
and new Plugs for when the problem is fixed.

So parts wise..
All that is left that I can come up with being a possible problem is the Petcock.
ON position it bogs out like it did before I took it to the garage.
RES it runs as fine as it can right now, not fine at all but fine in comparison to the ON position.

Hoses are not clogged or pinched.

Therefore I think maybe the petcock is bad.

But I have absolutely No idea how to tell if its bad or not.

Didnt pay attention to it the times I had it out but is there a way to take it apart?

Or ANY way at all to test to see if its broken or not and not questionable.

Sorry for being a pain but I've wasted Enough money on this bike already and I'm Done doing that.

Going to google it now to see if I can come up with anything but any advice on how to troubleshoot a petcock would be Awesome! 

Thanks

(edit)
just read a Ton of complaints on GS500 petcocks (stock)
and a bunch on how its basically not very good.
and that its suggested to be replaced.

So any suggestions on a replacement that isnt Very pricey would be sweet too.

[gs500e]

I figure you're talking about the frame mounted petcock (I bought some fancy fuel tubing from ebay while i was at it, total cost was $40.. but just the petcock is about $25) (mine mounted to frame without the grinding some bit off of it):
http://gstwins.com/gsboard/index.php?topic=56352.0

If you're talking about the tank mounted petcock, get an OEM one i reckon... pingle's are expensive.

Can test the petcock... but you already did basically: if it works better in one position than the other == issue (though, imo... that does not rule out fuel tank, fuel tank petcock, hoses between tank and frame petcock, etc).

[the mole]

Have you taken the screen filter out of the bottom of the tank and cleaned it?

[ben2go]

If the bike runs on RES and PRI but has issues running in ON,then the petcock is bad.If you disassemble the petcock,you will more than likely damage the internal diaphragm.The link posted to my petcock replacement is really the best option cost wise,IMHO.It also eliminates the petcock vacuum operation which has been troublesome on many different makes and model bikes.

[bigfatcat]

How to tell if petcock is bad ?  One way is to temporarily eliminate it and associated fuel lines entirely, ie bypass it.

Get some tygon or similar plastic tubing (maybe 1/4" iirc that's what i use), a small gas engine fuel petcock, a filter, a T-fitting so you can plumb primary and reserve into one line going to carb connection.

Tygon Fuel and Lubricant Tubing F-4040-A  (transllucent yellow)

http://www.youtube.com/watch?v=WzFevY8zfrc

http://www.repairclinic.com/Small-Engine-Filter-Parts

Should cost no more than $10 if that.    You can test the new setup by timing flow into an empty container before connecting to carb inlet - i get ~ 7 gph on mine which is plenty plenty for the gs500 (just to make sure the cheap filter isn't too restrictive -btw filter is optional but I have a slightly rusty tank)

u don't need clamps if tubing fit is snug enough.

This set up works well for me for 3 yrs so I never went back to the oem setup - don't want to have to troubleshoot that on the side of the hi-way if I ever break down.

Always remember to turn that valve OFF when done riding else your carbs will overflow overnight.

If your problem goes away then probably the oem petcock/fuel lines/vac line was the problem.

If not then  u have more troubleshooting to do .

[ben2go]

How to tell if petcock is bad ?  One way is to temporarily eliminate it and associated fuel lines entirely, ie bypass it.

Get some tygon or similar plastic tubing (maybe 1/4" iirc that's what i use), a small gas engine fuel petcock, a filter, a T-fitting so you can plumb primary and reserve into one line going to carb connection.

Tygon Fuel and Lubricant Tubing F-4040-A  (transllucent yellow)

http://www.youtube.com/watch?v=WzFevY8zfrc

http://www.repairclinic.com/Small-Engine-Filter-Parts

Should cost no more than $10 if that.    You can test the new setup by timing flow into an empty container before connecting to carb inlet - i get ~ 7 gph on mine which is plenty plenty for the gs500 (just to make sure the cheap filter isn't too restrictive -btw filter is optional but I have a slightly rusty tank)

u don't need clamps if tubing fit is snug enough.

This set up works well for me for 3 yrs so I never went back to the oem setup - don't want to have to troubleshoot that on the side of the hi-way if I ever break down.

Always remember to turn that valve OFF when done riding else your carbs will overflow overnight.

If your problem goes away then probably the oem petcock/fuel lines/vac line was the problem.

If not then  u have more troubleshooting to do .

I understand what you're saying.By the time everything is purchase to bypass the frame petcock,one could just order a new upgraded petcock for close to the same money.The CRF250X petcock eliminates the vacuum issue altogether.The factory petcocks do fail.It's just a matter of time before they do and sends the owner searching for the problem.Even shops over look the problems with the petcock and send bikes home with bad ones.So a new CRF250X petcock can completely eliminate the issue for good.

[sledge]

Did anyone ever credit Slowinthestraights for coming up with the idea in the first place??

http://gstwins.com/gsboard/index.php?topic=36958.0

[Tombstones81]

Did anyone ever credit Slowinthestraights for coming up with the idea in the first place??

http://gstwins.com/gsboard/index.php?topic=36958.0

Yes thank you to him and Ben2go for http://gstwins.com/gsboard/index.php?topic=56352.0 

Ordered a new petcock since it was only about $40 shipped for the one thats listed in both threads.

now to get ready and go get those tiny O rings for the top of the carbs.
and see about all new hoses.


But I noticed 3 hose attachments on that petcock, stock has 4 i believe.
What about the Right side Vacuum port on the carbs?
Doesnt that hose go to the rear attachment on the stock petcock?

I gotta look that up, buddy who was workin on mine the other day thought it did and hooked it up to it.
I assume that doesnt need to be hooked up to anything?

(edit)
nvm, read further down and it says to cap it.

and thank you Sledge for that link

[BaltimoreGS]

The factory petcocks do fail.It's just a matter of time before they do and sends the owner searching for the problem.Even shops over look the problems with the petcock and send bikes home with bad ones.

That's not just Suzuki's, a friend had a Honda Nighthawk 750 that had a bad petcock that went mis-diagnosed a few times before a good mechanic figured it out.

-Jessie

[ben2go]

Did anyone ever credit Slowinthestraights for coming up with the idea in the first place??

http://gstwins.com/gsboard/index.php?topic=36958.0

I don't know but I will add it to my write up.

[ben2go]

The factory petcocks do fail.It's just a matter of time before they do and sends the owner searching for the problem.Even shops over look the problems with the petcock and send bikes home with bad ones.

That's not just Suzuki's, a friend had a Honda Nighthawk 750 that had a bad petcock that went mis-diagnosed a few times before a good mechanic figured it out.

-Jessie

I have heard other bike owners say it's happen to them,so it's probably common with any manufacture running vacuum operated petcocks.