Choke cable return spring

Standard & electronic conversions

Choke cable return spring

Postby dyates » Sat Jul 23, 2016 6:53 pm

My choke cable even after adjustment is not completely releasing, resulting in a fast tickover. SU cutaways show a little coil return spring which is absent on my twin HS2 carbs.

Anyone tried a tension return spring, as used for the throttle linkage?
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Re: Choke cable return spring

Postby bmcecosse » Sat Jul 23, 2016 8:17 pm

There is not normally a separate return spring on the 'choke' - it works on a push-pull principle. There should be little springs on the side of the choke lever on each carb - short coils about an inch long - which do pull the jet up as the choke is pushed in. Are these missing? A picture of what you have would help.
 









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Re: Choke cable return spring

Postby Panky » Sat Jul 23, 2016 8:55 pm

Like these?
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20160227_131156.jpg
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Re: Choke cable return spring

Postby dyates » Sun Jul 24, 2016 8:20 am

These look to be throttle return springs......
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Re: Choke cable return spring

Postby dyates » Sun Jul 24, 2016 8:24 am

Bmecosse : see above, the torsion springs on the 'choke' control shaft are missing, which is why I intend to replace them by tension springs, like the throttle linkage
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Re: Choke cable return spring

Postby bmcecosse » Sun Jul 24, 2016 5:20 pm

Depends on the age of the carbs - I can't see the jets clearly in that link. The springs you show are the throttle return springs as mentioned above. There is usually an additional 3rd spring operating directly on the throttle cable lever. Not aware of any return springs on the 'choke' other than the small springs I mentioned earlier, to hold the jets up tight when the choke cable is pushed home. You do realise that twin 'tiny' SUs like that are scarcely any better than a single SU of the same size fitted on a good inlet manifold with no water heating or 'hot spot' That's the only advantage the twins have (even the flow into the head is no better because it is disrupted by the cross tube ) - no heating of the mixture as it flows in to the head. And sadly - these pan cake filters are no good either - the face opposite the carb intake must be at least 1.5 X the diameter of the carb intake away from the carb. so for 1.25" carbs they need to be 1.5 X 1.25 = almost 2" deep.
 









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Re: Choke cable return spring

Postby dyates » Sun Jul 24, 2016 6:46 pm

Thethird time that you have made the remark about my twin HS2's. As before they were on the car when I bought it, so I am highly unlikely to spend money converting to a single carburetter when I am getting excellent performance and good petrol consumption.
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Re: Choke cable return spring

Postby bmcecosse » Sat Jul 30, 2016 7:39 pm

Oh well - lead horse to water etc etc...
 









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