1981 GS1100E Idles ok. Turn throttle instant death.

[c&c]

Thank you for your response. Much appreciated.

Found this diagram of the BS34 carb. It's the closest I found. Final I see what the hell is happening in there!

My cold start problems was my own doing. I installed the choke leaver on the carb the wrong way.
Reinstalled it the correct way. Now in works like a charm. I now see where the choke is getting the fuel from.

If I understand, you are saying that my idle jet passage is still clogged. (thanks diagram) That would explain why the throttles first 1/4 is erratic/burps with hesitation.

Ok so I'll set the floats back the way they are suppose to be and I will make sure the idle jet passages are free of debris/junk.

The idle MIXTURE adjustment screw, which they call Pilot screw on the diagram, when unscrewing does not add more fuel, it allows more pre-set mixed air and fuel to enter the engine. Like you mentioned it's a "pre-set MIXTURE" dictated by the pilot jet and air pilot. Which would also explain why the ColourTune stays the same colour no matter what position the Idle Mixture adjustment screw is in.


So maestro do I finally "get it"?

[Steve]

Found this diagram of the BS34 carb. It's the closest I found. Final I see what the hell is happening in there!

That is a rather generic diagram, try this one; (if it wasn't identified as an 850 carb, you would not know the difference. This is a BS32, yours are BS34.)



This picture was doctored up some time ago to show the location of the rubber plug, but is a better shot to show the pilot mixture passages.


When you get to (re-)cleaning the carbs, pay special atttention to the transition ports at the top of the throttle blade.

Some bikes have two, others have three, but there is always one that is open all the time. When the throttle is closed, it will admit as much mixture as it can, but it's not quite enough, which is why you can add more with the mixture (pilot) screw. As the throttle is just barely cracked open, another port is opened, now you have three places where gas is being added to the incoming air. By the time the throttle is opened a bit past the last transition port, the overall vacuum level will drop a bit, reducing the pull through the transition ports, reducing the amount of gas that comes through them. That is when the air flow is sufficient for the needle circuit to start flowing enough to handle the mid-range throttle settings.

The idle MIXTURE adjustment screw, which they call Pilot screw on the diagram, when unscrewing does not add more fuel, it allows more pre-set mixed air and fuel to enter the engine. Like you mentioned it's a "pre-set MIXTURE" dictated by the pilot jet and air pilot. Which would also explain why the ColourTune stays the same colour no matter what position the Idle Mixture adjustment screw is in.

I would think that the Colortune should show some differences, because, even though you are adding a pre-set mixture, you are adding that mixture to plain AIR, so you are still changing the overall mixture. However, on the three bikes with CV-type carbs that I tried it on, I never saw any change in the burn color. The flame simply started to flicker a bit, then went OUT as I turned the mixture screws in. The flame came back as I turned the mixture screws out, so I went for "steady flame" rather than "bunsen burner blue". On the one bike with VM carbs that I used the Colortune on, it was GREAT to see the flame change color. That was the first one that I did, and it got me all excited to use the Colortune on the other bikes.

So, yeah, the Colortune does work, just not for all bikes.

.

[c&c]

WOW! Thanks for the much better cut outs. Makes even more sense and much easier to understand the internal workings. Without that it's pretty hard to know why an adjustment does what it does or does not do.

I will recheck the transition ports for sure.

I also noticed the flame going out but did not make sense of it. I did notice a change in idle speed/sound when adjusting the screw. I'll also use the "steady flame" while adjusting.

A good chance you guys are here. With out this help it would be practically impossible for us mere mortals to get our bikes up and running properly.

[Steve]

A good chance you guys are here. With out this help it would be practically impossible for us mere mortals to get our bikes up and running properly.

Thanks.

We have seen more than a few new guys that were rather adamant about how "clean" their carbs were or how meticulously something else was done,
but we kept reading what they had done and kept trying to convince them that it wasn't right. Thanks for seeing the light.

Resistance is futile. You WILL be assimilated.

.