XJ1100 hanging idle

[HalfCentury]

Tonight I pushed the XJ1100 into the driveway, hooked up a tuning bottle with a T-splitter, filled up the bottle 1/2 way, set the choke at 1/2 way, and cranked the engine. Within 4 or 5 seconds, the engine caught and immediately revved above 3000 rpm. I shut it off and check the idle screw and made sure that the idle screw was at minimum.

After a few starts, and they all are high idle, I stuffed some shop towels into the snorkel. This reduced the idle RPMs a little but not what was needed.

After a few starts, the idle is 5000 to 5500 RPM.

The intake boots have been replaced and sealed with Yamabond #4.

The airbox is stock with a very clean filter. All of the rubber boots on both sides are soft and clamped tight.

There are caps on the intake boot nipples.

I am thinking that maybe one or more of the carb slides are stuck in the open position. I will remove the easy carb hats and check the slides for clunk smoothness. I guess I should also check the idle screws for how many turns out they all are.

The good news is that the brakes are all working and have new stainless lines. Once the idle is sorted out, it should be good to drive.

Suggestions are welcomed.

[donebysunday]

Cable

This may be dumb on my part but by any chance did you have the handle bars turned way to the right. If so the throttle housing on the right side may be pulling on the throttle cable causing it to open the carbs butterflies.
Check how tight that cable is ?

[red bandit]

I am thinking that maybe one or more of the carb slides are stuck in the open position. I will remove the easy carb hats and check the slides for clunk smoothness. I guess I should also check the idle screws for how many turns out they all are.

If you have to say that then you should take the carbs apart and clean them and make sure things are moving properly.

[HalfCentury]

This may be dumb on my part but by any chance did you have the handle bars turned way to the right. If so the throttle housing on the right side may be pulling on the throttle cable causing it to open the carbs butterflies.
Check how tight that cable is ?

I just did a double check. The cable is loose. The bike has been on the center stand in my garage for months during the teardown and rebuild. Handlebars are always straight ahead.

[HalfCentury]

If you have to say that then you should take the carbs apart and clean them and make sure things are moving properly.

That would be the last resort. During installation of the hats, one of the slide diaphragms was difficult to make remain in place in the groove. If it is not seated in the groove then that could explain the apparent extra air.

The idle screws may not be set properly. So, yes, the carbs may have to come off again. This airbox is a royal pain to move out of the way.

[BA80]

Check that the throttle linkage on the carbs isn't hanging on one of the boot clamps on those boots you just installed.

[HalfCentury]

This may be dumb on my part but by any chance did you have the handle bars turned way to the right. If so the throttle housing on the right side may be pulling on the throttle cable causing it to open the carbs butterflies.
Check how tight that cable is ?

This looks like a good call. There was quite a bit a excess tension at the threaded adjuster at the beginning of the cable at the grip.

I backed the tension out completely and adjusted the idle screw at the carb bottom to accept the slack.

Now it is raining outside. When the weather breaks, I will pull it out and try it again.

[HalfCentury]

This may be dumb on my part but by any chance did you have the handle bars turned way to the right. If so the throttle housing on the right side may be pulling on the throttle cable causing it to open the carbs butterflies.
Check how tight that cable is ?

This looks like a good call. There was quite a bit of excess tension at the threaded adjuster at the beginning of the cable at the grip.

I backed the tension out completely and adjusted the idle screw at the carb bottom to accept the slack.

Now it is raining outside. When the weather breaks, I will pull it out and try it again.

[HalfCentury]

Success

The throttle cable tension was the solution. Adjusting all of the tension from the carb side throttle, the idle RPM was too low. Adjusted that above 1000 and then did a sync with the Carbtune Pro.

All four vacuum reading are close enough to call it good for now.

Interesting observation. Before the sync adjustment, carb 3 and carb 4 were much higher vacuum reading than carb 1 and carb 2. The throttle response was very fast revving to 5000.

After the complete sync, the throttle response seems to be slower. Any explanations why the throttle response seems slower after balancing?

[donebysunday]

Ready go

The throttle cable tension was the solution. Adjusting all of the tension from the carb side throttle, the idle RPM was too low. Adjusted that above 1000 and then did a sync with the Carbtune Pro.

All four vacuum reading are close enough to call it good for now.

Interesting observation. Before the sync adjustment, carb 3 and carb 4 were much higher vacuum reading than carb 1 and carb 2. The throttle response was very fast revving to 5000.

After the complete sync, the throttle response seems to be slower. Any explanations why the throttle response seems slower after balancing?

In MHO the carbs that were at a higher vacuum were, how should I say, pulling the other cylinders along so basically giving the engine a head start towards revving.
Please excuse my explanation ! I just barely completed high school.

Now you have all the cylinders working on their own and together of course.
If you want faster response turn your idle up and give all the cylinders a head start.