What causes the unstable idle speed in Commandos?

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When you were able to get your 1800 idle to drop by loading the engine, then something has to have physically moved. The throttle slide or the AAU returning back into position. I would check the operation of the throttle slide with your finger in the bore, a nice smooth operation, then watch using the hand control. Cable could be dry, corroded internally as norbsa said. I've read some good posts where the AAU is said to have physically worn to where it doesn't like to return, most likely from not greasing any pivot point prone to wear. Also AAU springs loosing their "spring."

Best of luck, I think with a little patience you can figure this out!
 
I still think it is air leaking by the trottle that "allows" the engine to keep the 1800 rpm with the trottle closed. At this speed I assume the AA unit weights are still advancing the ignition "helping" the rpm to stay high.

But I still think the problem is leaking trottles (at least with Amal carbs) but I might be wrong, maybe it's not a common problem with Mikuni :?

The fixed carb trottles did the trick on my bike but I still had a slightly higher idle from time to time but that disappeared when I serviced the AA unit.

/Per
 
You need to check the slide, is it scratched? Is it from a too thick cable?


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The original source of the text can be found here: http://www.factorypro.com/
>Technical Support
>Motorcycle Tuning Tech
>CV Carb Tuning
>Low RPM Engines.



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grandpaul said:
Don't edit it out, MAKE IT A STICKY!!!
Click to expand...

The original copyright will be owned by the author, or owner of the website, where that information is originally published, presumably?

Quote from the original website page:
"Please do not plagiarize this page - it took years to develop and write and is not based on any other previous work by anybody else. If you want to link to this page on your site, please ask - we are perfectly willing to allow links as long as proper credit is provided. Thanks - Marc"


The information is also intended for tuning CV carbs, although no doubt, much of the information could still be relevant to slide carbs.
 
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