running woes

[devilschld]

carb kits and intake boots were just put on my bike. now that all vaccum leaks are fixed cannot keep bike running or it wants to stay at high idle. but when you remove the electronic ignition cover and run the vaccum advance it stays runningand idles down fine. if u disconnect the vaccum line from the advance and from the intake boots and connect the one from intake to the carbs the bike will idle just fine but stil have no vaccum to run the advance. help i am stumped

[randy]

devilschld;

Not sure what you mean by 'run the advance', do you mean turn the plate by hand?

The line from the vacuum advance should be connected to carb 2, NOT the intake boot.

Also, after carb work the carbs should be syncronized. Unsynchronized carbs can create symptoms that appear to be caused something else (runaway idle, poor idle, rough running, poor mpg, yada yada). Synch them and change the hose routing, then let us know what you've got.

[devilschld]

yes i have to run it by hand. the carbs appear to be in syc.and yes the vaccum advance is connected to #2 carb and i have a line that connects to number 2 intake as it was when the bike ran better but the intake boots were bad and the carbs were varshied.

[randy]

That line to #2 intake boot, where is it connected to?

Carbs cannot 'appear to be' synched, they are either synched or not, how did you check the synch?

[mro]

for starters

What year/model XS do you have?
Did the carb kits come with jets, and did you use them?
What did you set the float height to?
Did you "pre-synk" the carbs before you put them back on?
Are you trying to run it without the air filter installed?
If you have BS34 III carbs, has the plug covering the pilot screws been removed?

Sorry for the third degree but hard to know what advise to give without a little back ground.


mro
BTW, welcome to XS land

[Ken Talbot]

Re: running wows

Originally posted by devilschld
carb kits and intake boots were just put on my bike.

There's also a very good chance you've got the wrong main jets now and your carbs are way too rich. Did you research the various articles and posts on carb jets to ensure you got the correct ones? Prom's recent post here gives a good summary of this issue.

And, to repeat Randy's and MRO's advice, carbs cannot appear to be sync'd. If you or somebody did not put a set of gauges on them and actually sync them, they are not sync'd.

[devilschld]

running woes

hello, I put the carb kits in this bike. I used a digital vaccume gauge to try to sink the carbs. The bike would not steadily idle long enough for me to get a good reading. But, I did get the carbs to level out to about 50 hg. It will idle for about 30 to 45 seconds the tries to fall and die. If you rev the engine past threethousand rpm then the idle hangs up for about 30 seconds then it will settle down idle for awhile then try to die again. As far as the advance goes, we were holding the arm that hooks to the vacume pot the bike ran fine then and would idle fine?If there is any advice to be had it would be appreciated.

[randy]

devilschld;

Before we can help you any further, please answer some of the questions above.

[mro]

we were holding the arm that hooks to the vacume pot

A shot in the dark...
Probably not firing on all 4.
When you move the "arm" you are also moving the pick-up coil wires which send a signal to the TCI so it knows when to fire the coils/plugs.
They have been known to break.
Moving the "arm" might be allowing them to make contact and then you get it to idle.

Take a look at this
http://www.xs11.com/forum/showthread...=&threadid=543


mro

[skids]

Re: running woes

What is 50 hg? 50 cm mercury? It would seem that you did not synchronize the vacuums near idle. If you synch then at higher rpms, they will definately be out-of-synch at idle and off idle. It can make the rpms "hang" when you let off the throttle (so can leaky manifold boots).

Originally posted by devilschld
But, I did get the carbs to level out to about 50 hg.

[devilschld]

Could not get the bike to idle long enough at 1100 to 1200 rpm . do not have a service manual to get any settings from. One other thing is that if we took the vacume line that goes to the fuel valve the bike would seem to run better.

[DiverRay]

Did you try and "eyeball sync" the carbs BEFORE putting them on? A lot of the members talk of "breadtie" sync, and it's the same thing. You get the four butterfly valves so they look like they are open the same amount, and that will usually get you close so the engine will run.

[mro]

do not have a service manual to get any settings from

Start here >>>http://www.xs11.com/specifications/serialno.shtml
to deturmin what model you have.
78/79 carbs are BS34 II, 80/81 are BS34 III
design change, float height, jets etc are different.

Stock Float Height: 78/79 25.7mm, 80/81 23mm
Float height is set by turning the carburetors upside down and removing the float bowls and measuring with a caliper from the gasket seat of the carb to the highest point on the floats. Both sides of float need to be checked and all 4 carbs set the same height.

"Pre-Synk" click here>>>http://www.xs11.com/forum/showthread.php?s=&threadid=88

Set pilot screws out 1 1/4 turns from "lightly seated"...
Screw em in to far or hard can break off the point and leave it lodged in the carb which will make it imposible to get that cylinder to funtion properly.

If your carbs be clean, then your XS should run good enough to tune the carbs. (Vac synk, adjust pilots etc...)


mro
BTW, should you have after market exhaust and/or pod filters then tuning will be a little more of a challenge but is done succsessfully by guys here on the forum all the time.

[devilschld]

running woes

thank you for the information, will put it to use and will let you know how it goes.

[devilschld]

i maybe in a shoping mood really soon for a set of carbs on my 1980 xs1100 special completly rebuild and ready to go does anyone have some or willing to sell the rebuilding