HELP! 1980 GS850G Starts, but stumbles-Pops-won't rev??

[Darin Jordan]

OK guys... You were right...

Woke up this morning to a house full of fuel odor. Fuel petcock rebuild was a failure... Gas was overflowing out of a couple of the carbs. Got a fuel can and disconnected the fuel line, connecting another to drain the tank. Fuel freely flows right on through.

Not sure if I rebuilt it wrong, or if it was just a bad quality rebuild kit. Was a "K&L" kit.

I've read here that this is may be a typical problem and that a new petcock is the only cure. REALLY? What is it about rebuilding one of these that is so touchy? Seems pretty simple inside. Is it just a bad kit? Can a petcock be rebuilt successfully, or should I just pop for a brand new one??

The wife was NOT happy to be awaken at 4:00am to that smell in the house (split level, garage is just below the bedrooms...). SHE wants this fixed right!

 

[Darin Jordan]

I just replaced the one on my 850. Best price I found for the reservoir kit was Parts-n-More. I also got the rebuild kit and o-rings for the calipers.

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Thanks... I'll check that out.

 

[Darin Jordan]

AND... Just so I have this straight... even with perfectly funtioning floats and needle&seats, it would still be "normal" for the float bowls to fill up while not running the bike, and fuel to start coming out of the needle-jet, etc??

That just seems so counter-intuitive to me, since the purpose of the needle&seat and floats is to stop the carb from filling up any further.

I'm asking, because I'm tempted to just put in new needle&seats and floats. However, they all looked and functioned fine on the bench. They are metal tipped needless and looked shiny and new, and the floats, well, floated...

Just double checking so I don't have to spend money on something that isn't broken.

I need to add a "BassCliff" style signature to my profile that says "Thanks for your PATIENCE!"

 

[Ranger]

AND... Just so I have this straight... even with perfectly funtioning floats and needle&seats, it would still be "normal" for the float bowls to fill up while not running the bike, and fuel to start coming out of the needle-jet, etc??

That just seems so counter-intuitive to me, since the purpose of the needle&seat and floats is to stop the carb from filling up any further.

I'm asking, because I'm tempted to just put in new needle&seats and floats. However, they all looked and functioned fine on the bench. They are metal tipped needless and looked shiny and new, and the floats, well, floated...

Just double checking so I don't have to spend money on something that isn't broken.

I need to add a "BassCliff" style signature to my profile that says "Thanks for your PATIENCE!"

I rebuilt my petcock, mainly I bought a stiff spring from the store and cut it slightly shorter than the original then stretched it and replaced the o ring and no problems. Bike creates enough vacuum to overcome the extra force with the springs I chose.

The bowls will fill up if you're leaking fuel yes because the floats will prevent fuel from flowing into the carbs but for how long is a gamble as you found out.

My temp solution was I put a shut off valve into my fuel line to prevent leaking guaranteed until I got around to fixing my petcock.

 

[Darin Jordan]

Figured out what was wrong with the petcock rebuild.

Removing the dial, it was apparent that the plunger with o-ring on the diaphram was not extending far enough into the petcock to make a seal. Wasn't even making contact.

I took it apart and looked it over. I suspect that the metal disc on the backside of the diaphram was warped a tad, and was bend slightly backwards (toward the inside of the bike), preventing the plunger from reaching deep enough into the petcock hole. It came this way, so I suspect it happened during packaging or just through the normal production process.

I have fixed it, I believe, by drilling a 1/2" hole in a piece of hard wood, covering the wood with a piece of packaging tape to protect the rubber, and then, with the plunger side down inside the hole, using a small drift to tap on the backside of the plunger and gently bend the disc back into the correct position.

I verified fitmet by removing the dial, and mounting the diaphram, then looking inside the center of the petcock to make sure the plunger was aligning correctly and was centered and seated. It was, so I buttoned everything back up.

I also gave the spring a little stretch to increase it's preload a little. A slightly stiffer spring may ultimately be in order, but it seems to work now. I gave it the "suck test" and it feels like it's now sealing. Will reassemble onto the bike and find out.

I may install a second fuel shutoff, just to have the backup for longer storage, but we'll see how this works.

 

[Darin Jordan]

Seems I've transitioned my troubleshooting info to this thread...

http://www.thegsresources.com/_forum/showthread.php?p=1369210#post1369210