Only runs when choked

[rebel88]

Hello all,
I am new here and just picked up my first bike an 82 xs400. I'm having some trouble getting my bike running correctly. My problem is getting the bike to idle without having the choke on. I have pulled the carb and cleaned it out and I have also changed the spark plugs and battery. It fires right up and will run for a while on half choke, then it will start to bog down and die. If the bike isn't choked then it won't start or continue running.

Side note: my exhaust is busted on the left side.

I'm not sure where to go from here since I already cleaned the carb and I have an inline fuel filter. Is this a carb syncing issue or is it a backpressure issue caused by the busted exhaust?

 

[markjs]

Did you do a soak or just spray cleaner and air? Sounds like a gummed carb to me. I boiled mine in vinegar and water after stripping them down.

 

[willem]

Yea it took me 3 tries to get my carbs cleaned right. Just try again and make sure you probe through ALL the passages, there's more to it than you might think at first. Also use the thinnest wire you can find for it.

 

[rebel88]

Okay thanks, I'm going to pull it out again and poke through all the passages and boil it. I will let everyone know how it goes.

 

[XSLeo]

With the carbs of the bike Open the throttle. Look in where the throttle plates are. You will find several tiny holes by where the throttle plates close.
Now remove the air mix screw. Using a spray can csrb cleaner and the plastic tube spray cleaner in the screw hole. Does cleaner come out all the tiny holes?
With the flost bowls off and spraying cleaner in the mix screw hole does cleaner come out the pilot jet?
Spraying cleaner in the pilot jet does it come out the mix screw hole as well as the tiny holes? Keep working at it till it does. I use the tie off a loaf of bread. Strip off a bit of the cover. This leaves a thin soft wire. Carefully probe those tiny holes. Spray cleaner through.
Eventually you will get spray to come out all the places mentioned.
Leo

 

[Scorpio1963]

Last year my bike had a similar issue,I found a very dirty petcock which i cleaned thuroughly,I clogged jet in the carb and screen on the petcock inside the tank was clogged up with varnish and or crud.

 

[willem]

I used a piece of wire from a wire brush (just pulled it out of the brush) because I couldnt find wire thin enough for my passages. Another advantage of thin wire is that it bends easily, so you can go all the way through your passages, even around corners

also just blow into the little holes (yes, with your mouth on the carbs) to make sure they're really open If you blow into the vacuum chamber you can also check if that's working well.

 

[Drewcifer]

Not sure why people say they had to clean their carbs Three times.

You physically remove the jets, the filters, the fittings, the float bowl valves, and and all other parts, and soak it overnight in pinesol or boil it in vinegar, or lemon juice.

If you hit up a few local parts places you could even find an ultrasonic cleaning place to be sure all your sub-passages are cleaned out, even though I've never seen them clogged before.

I suspect the failure is elsewhere.

 

[Scorpio1963]

Im with you Drecifer.Unless you did what I did and left fuel bowl gasket on the other carb

 

[willem]

I had to clean my carbs three times because the first time I didn't know what I was doing and my wire was not thin enough to probe through the passages. No improvement there.

Second time I got thin wire, but forgot to probe through half the jets. Also I installed the float needles upside down so ended up leaking fuel everywhere

third time I got it right.

 

[Scorpio1963]

I had a bosss long time ago drill this saying in my head,"Pay attention to detail"I still forget to do chit.

 

[16VGTIDave]

If I knew then what I know now, it would have only taken me one cleaning...

 

[Telecasterjoey]

Running only when choked to me sounds like its starving for fuel, is there an air leak in your fuel line? or your petcock/line clogged? I've seen this happen.
Just my .02 since it sounds like you've gone over the carbs quite thoroughly I'd start looking elsewhere.

 

[16VGTIDave]

One might think that, and if the "choke" actually was one this diagnosis might be correct. But what we call a choke is actually a cold start enrichment circuit. Entirely different operation to perform a similar task.

 

[Scorpio1963]

Take the carbs apart buy a rebuilding kit and if you plan on jetting get the neccasary jets while you have your carbs apart.Take your petcock off clean and rebuild if neccasary.Clean your screen that goes into the gas tank.BTW I never boiled my carbs I boought a can of chemdip and let my carb parts soak in that stuff.Cost about $12-$14 a can but worth it.I have used this stuff for years rebuilding carbs.