Hey All!
Is there a way to verify that the petcock is functioning properly? I can't get my sons 80 to run at idle. Runs fine on the throttle, but always dies at idle. Only starts or idles with choke on. I have read on this forum that a Banshee petcock works? How do I know if I need one.

Thanks!

 

Disconnect the fuel line and turn on gas, watch for flow. probubly safest to drain into a can or container. I would guess it is ok. It takes more gas with choke on and on the throttle than ehen idling. Possibly dirty carb or air screw in need of adjustment.

 

Thanks Mywifesquad!
By air screw adjustment do you mean the "throttle stop srew" on the same side of the carb as the fuel line inlet?
When I remove the air cleaner assembly I can cup my hand over the air intake opening and keep the bike running. Once I pull my hand away it stalls.

Thanks for your help.

 

Air screw is usually located just above the float bowl gasget line. Not idle or throttle stop screw. I am not a LT80 owner so I don't know for sure where your's is. Your symptoms make me think that your carb is dirty. I would take it apart, clean with carb cleaner and blow out all passages with compressed air.

 

There is no air screw on LT80s [img]i/expressions/face-icon-small-smile.gif[/img]
You have a piece of dirt in the pilot jet. Remove the carb and clean.[img]i/expressions/face-icon-small-wink.gif[/img]

 

The LT80 petcock is "vaccum activated". IE: When you turn the petcock to "on", no fuel should come out of it. The fuel is drawn/pulled from the petcock by vaccum when the motor is cranked around or fires up. If the carb fuel bowl is empty you switch the petcock to "prime" for a minute and fuel will flow to fill the bowl. Then switch back to on. The Banshee petcock is a direct bolt on and works well. If you decide to install one, you'll have to plug off the vent line on your stock carb as the Banshee petcock has only uses (1) line.

Rude Dog

 

Thanks for all your help guys.
I have taken the carb apart and completely cleaned it and I stll have the problem. When I stab the throttle quickly it bogs at first, then eventually it catches and runs ok. When I get off the gas, it does not come down off the RPM's right away. It almost feels like the throttle is sticking, but it is not. When it finally does come down to an idle, it will not run smoothly and dies.
I must admit I am a bit frustrated, and do not know what to do from here. Should I buy a carb kit and rebuild it? Would trying the Banshee petcock get me anywhere?

Thanks again for your help!

 

Latemodel, I understand your frustration, I have been there. It seem's to me that you have a lean condition, just not sure why. As you can see from my post's that I am not too familar with the lt80. There is a lot of people here that have these quad's so maybe they can help you more. I would look for a vacuum leak. I dont know how old this is but I would look at cylinder gasget, carb manifold to cylinder gasget, carb boot. The way that I look for vacuum leaks is with carb cleaner, with the quad running as best you can get it to. Spray a little carb cleaner around the carb mount cylinder gasget etc... if engine either dies or smooths out you have found your leak. The other possibility is leaky crank seal on ignition side. I would not spray carb cleaner there but that seal can be checked visually if you remove the flywheel. My son's cr250 had same problem and it turned out to be the crank seal. It had a build up of oil around the seal and it was obvious it was leaking. As a final suggestion, I know you dont want to hear it, but some times it has taken me 2 carb cleanings to get out all dirt, never understood why.

 

Just to be sure,, when you cleaned the carb, you removed both jets and made sure the lil holes were clean?
I feel the petcock prolly isn't the problem here cuz it runs fine on top.
We'll get ya going. [img]i/expressions/face-icon-small-smile.gif[/img]

 

Ran the bike spraying some carb cleaner around the base of the carb and there was no evidence of a leak. I also replaced the o-ring on the plastic insulator and checked it for any cracks.

I will pull the carb apart again tonight and give it another cleaning. I was fairly certain I got it all clean, but since it is so simple to pull it off, I will go through it again

I will let you guys know if I am successful, and hopefully I am, cuz the look on my poor son's face is killing me!