85 GS1150EF choke operation query

[1150newb]

As mentioned ad nauseum, my 85 GS1150EF project did not run when I got it. As part of my rebuild I cleaned my carbs but did not bench sync them. I believe I sufficiently cleaned all orifices etc. Upon reassembly I did not pay real close attention to the choke mechanism (all the slidey parts at the carbs). I can get the bike to start however the choke appears to do nothing. Full engagement of the thumb lever, no throttle, full battery, petcock at PRI, bike will sputter but not catch. I ultimately end up firing the bike with the choke off and use the right hand grip. Firstly, will a carb sync at my tech shop make the difference I'm looking for? (Fast idle at initial start up) Can that cable assembly be adjusted? Is it not doing its thing at the carb end of things? Or do I really have to go back into the carbs. I currently have the tank off and if I can fiddle with the carb end of the choke mechanism now would be the time. Thoughts?

 

[BigD_83]

If it will fire up without the choke, then it is too rich. If you have to crack the butterflies, then the bench synch is likely not correct. They should be very slightly and equally open with the throttle closed.

Are you saying that when it does eventually start up the idle races? How high does it go?


I know you have probably heard it a bunch having previously owned a GS, but you should learn how to work on the carbs yourself, if you have the space to do so. It is a rare shop these days that will have the knowledge and inclination to properly work on carbureted bikes. Your tunaround time is much better, and you can make faster progress when you can see the immediate results of a change, too.


When cleaning the carbs, did you make sure you did not get any of the rubber parts in the carb cleaner, particularly the plungers of the choke?


The racing idle is often a too-tight throttle cable. That can be adjusted at either end, but can be caused by a bent throttle linkage bracket on top of the carbs.

 

[Steve]

As part of my rebuild I cleaned my carbs but did not bench sync them.

What was your incentive for only doing part of the job?

I believe I sufficiently cleaned all orifices etc.

What method did you use to clean the carbs? Especially for a non-running "project" bike, an overnight soak in carb cleaner dip is highly recommended. No, scratch that, it's MANDATORY, unless you have an ultrasonic cleaner and use it.

Upon reassembly I did not pay real close attention to the choke mechanism (all the slidey parts at the carbs).

If you got the parts assembled in the correct order, there isn't much more to pay attention to at the carbs.

Full engagement of the thumb lever, no throttle, full battery, petcock at PRI, bike will sputter but not catch.

You mentioned that the tank is off right now. Look at the "choke" mechanism while you pull on the lever. Do you see it move? It should have just a little bit of slack when OFF, then all should engage at the same time. As you pull the lever over, they should all move.

I ultimately end up firing the bike with the choke off and use the right hand grip.

Obviously, something is mis-adjusted. You should need something less than full "choke" and NO throttle. Moving the throttle while using the "choke" defeats its operation.

Firstly, will a carb sync at my tech shop make the difference I'm looking for? (Fast idle at initial start up)

Yes and no. The carbs can be COMPLETELY closed, but will start using the "choke" because it uses separate air and fuel sources. However, if one or more of the carbs is open too far, it can upset the mixture enough that the "choke" will be less-effective.

Can that cable assembly be adjusted?

Yes. Where the cable attaches to the linkage at the carbs, there is a threaded adjuster.

Is it not doing its thing at the carb end of things?

As mentioned earlier, since you have the tank off, move the lever, LOOK at the mechanism on the carbs. Of course, that only tells you about the mechanism. There is always the chance that when you "cleaned" the carbs, you did not get all the gunk out of the enrichener ("choke") passages.

Or do I really have to go back into the carbs.

That would depend on what you see on the outside. My guess is that you need to clean the carbs. Yes, again, but this time, do it properly. NO SHORTCUTS.


One last thought. A "bench sync" assures that all the carbs are open about the same amount so each cylinder is drawing about the same amount of mixture. This will be close enough so you can start the bike and get it running so you can do a DYNAMIC sync with a set of gauges. Besides synchronizing the carbs, there is also the possibility that you simply have the idle speed mis-adjusted. There is no particular dimension to pre-set the idle speed, although some have suggested watching the idle speed screw as you turn it in. When it touches the linkage, turn an additional two turns. I have not verified that setting, so I don't know.

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