Wont idle

[joe smith]

Having a problem with the idle and need some suggestions..
It'll idle for about 20sec. and then it's like it loses vaccum and it slows and slows until it dies. other than that it runs like a top
thanks to an xslister named Z Ben!!
He has put in a lot of time on my bike and deserves some kudos for it!!! Thanks Ben.
We have checked the timing and also the cam chain timing. It was off a tooth or two on the exhaust cam.
Need some suggestions... All appreciated
Joe

[TopCatGr58]

Re: Wont idle

Originally posted by joe smith
Having a problem with the idle and need some suggestions..
It'll idle for about 20sec. and then it's like it loses vaccum and it slows and slows until it dies. other than that it runs like a top
thanks to an xslister named Z Ben!!
He has put in a lot of time on my bike and deserves some kudos for it!!! Thanks Ben.
We have checked the timing and also the cam chain timing. It was off a tooth or two on the exhaust cam.
Need some suggestions... All appreciated
Joe

Okay, Joe,
First, it's nice describe your bike, year, make, any mods like Indy filters/4-1 pipes, so that the GURU's (present company excluded!) can better discuss the particular carbs you have and how to tweek them.

Running "dry" after 20 seconds doesn't seem like enough time to empty the carb bowls, but I guess it could happen. Have you done your "TRIPLE" clean including the idle circuits? Are you sure your float valves are working, and that you have adequate fuel flow from tank to ALL carbs? Did you adjust the idle screws-1 for each carbs, not just the main throttle plate set screw? How many turns out from that screw's seated position? Hopefully you're talking about an already warmed up engine, not a cold freshly started one. Are you leaving the choke engaged after it warms up?? Right before it idles down to die, can you crack the throttle at the handlebar and bring it back to life?? Were the carbs visually synched, and or later vacuum gauge synched??

So you see, lots of things to check and consider, give us more info!

[joe smith]

The bike is a 78 xs 11. It was given to me by a friend. Him and his brother restored it and rebuilt the carbs. We have vaccum synched the carbs and have adjusted the individual idle screws 1and a quarter turns from seated. We got all the carbs synched but they were only registering about 4 ml bars of vaccum.
If I set the idle screw [main] at a postiton that will idle it wont come down from full throttle except to about 3000 rpm or better.

[joe smith]

And if it is dying i can crack the throttle and it is responsive.
Forgot to answer that in my last post ..
Thanks for all the help

[nashville_bill]

I wouldn't describe myself as a GURU, but it sounds like you have a bad vacuum leak.

[Mike F]

Hi Joe
Have you checked that the idle jet needles haven't broken off?
Keep revving

[maestro]

I had this same problem in my 78 XS11E. Turns out that there is a hose that runs out the back of your tank that lets it breathe. Well, my taking wasn't breathing. A quick way to see if that is the problem : open your gas lid and start it up. If idle smooths out, you've got only a small fix on your hands. I would try this before tearing out the carbs. Keep us posted. Good luck!

[oldnortonrider]

......heh, heh;...... the "hose", .....is called a "vent tube" .
Make sure , it's venting . ("breathing") .

[Ken Talbot]

I don't think the hose is vent for the tank. Rather it is a hose to drain off any rainwater or spilled fuel that might collect in the recess around the filler, under the filler cap. That's how it looks on both of my '81 standards.

[oldnortonrider]

Ken Talbot; ..... you are absolutely right !!
I can't believe, that I had forgotten, .....about 2 years ago, I wuz having a venting/breathing problem on my monster. It was making weird, squeeking, Jurassic Park critter, noises, around the tank lid, as it would create more air space in the tank, as it used fuel. And I had been having carburetion problems, not being able to solve.
Took the lid OFF, finally. Cleaned it; I could see the "breathing" hole was crudded up.
NOW, I HAD GOOD UN-IMPEDED, GRAVITY FLOW TO THE CARBS.
Alzeihmer's setting in.
Haven't been riding enuf, lately.
Improves my memory.
Also, now, I can remember (maybe).....; the gas tank, I wuz thinking about, was my old '86 Kawasaki Concours .
Interesting; .....I never refer to my '79 or '81 XS, as "old" .

My 3rd posting; I'm coming alive, now.

Thanks, again, fer the reminder.

J.Carlton Riggs

[joe smith]

Thanks for all the suggestions. I had a problem with the cap vent hole. It would bog down alot until i cleaned it out. I'll check the tube if there is one. I don't seem to remember seeing one but I will check it out..
Joe

[Jdwags]

Mine is so Speshul, it has not stinking hose !

[Snow]

My XS has appeared to develop the lack of venting problem - she stalled out on my after only about 1/4 mile of riding - when I got her to start up and get back to the house, I cut her off and noticed those ghastly "jurassic sounds" coming from the tank....it almost sounded like gas was boiling too. So, I lifted the lid and heard a "whoosh" of air enter the tank.

Now, my question is, how exactly do I clean out this vent hole in the cap? I have a standard tank from a 78E btw.