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Discussion Starter · #1 ·
I've had my '76 Shadow for about 5 years, she's had a fair amount of work done over this time.

I've now come up against an issue that's never occurred before.

She starts perfectly, occasionally takes a few seconds to run on all 8 cylinders, but then idles nicely regardless of air temp or weather.

This week at the exact same spot in my daily commute, she starts to loose power and won't pull away with out multiple pumps of the throttle. Once she's moving no issues. Stop at next junction, same issue. This only occurs after about 5 / 10 minutes of driving, which leads me to believe its heat related. After about 20 minutes the problem clears. Go back to her in the afternoon same issue.

I can only imagine it's the weirdness that is the auto choke?

Where should I start looking? Or am I completely wrong in imagining a choke related issue?

All ignition components are new, carbs very clean and balanced last year on a dyno.

Here's a pretty picture as payment for you time x

Wheel Tire Automotive parking light Land vehicle Car
 

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It does appear to be a choke issue where the choke cam isn't returning completely to the off position until you encourage it by pressing the accelerator. Perhaps a light oiling of the choke cam would cure it but don't get oil on the cam face. Use very light oil e.g., 3in1 or even a drop of ATF but not engine oil since it is too heavy & attracts crud. Also check the choke butterfly is properly centered and moving freely. Other possibilities are that the choke spring mechanism needs to be cleaned and oiled and/or the choke stove pipe is blocked, is leaking or the insulating cover has perished. Maybe the first thing to check would be that the carb dash pots have sufficient oil. Your Silver Shadow looks lovely.
 

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Probably the choke stove pipes. Watch the choke butterfly shaft arm, it points down when cold (choke is on) and moves up when the thermo spring gets heated by the air going through the stove pipes. The arm should move from down (45° down from level) to up (45° up from level) in 2 or 3 minutes. As shadow11 says don't let any oil get on the fast idle cam face, it will not work properly with oil on it. Check the arm operation and report back.
 

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Was that still the original coil in there; probably Lucas ?
And no, I'm not beating up on Lucas parts, if it is still in there, it did very well for a 46 year old coil.
If not Lucas, what brand was it ?
 
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