3 replies to this topic

[daddums]

Ok, I've been a numpty. I had the carb off to service it and removed the choke lever, but now I can't manage to reassemble it again.

 

I think I've worked out how to fit the main return spring between the carb body and the lever, but I can't figure out how the smaller spring acts between the the two lever arms (one which the choke cable connects to and the other which connects to the jet assembly).

 

 

I'd be very grateful if someone could send me a pic or a description of what to do, I've been fiddling for hours now...

[ADRay]

looks like HS4?

it’s a pretty tricky job. Took me no less that 2 dozen times of winding that spring until I got it right.

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[Ethel]

The outer spring returns the cam that operates the fast idle, if it helps. It should produce less torque than the inner spring does in its rest position so the fast idle operates before any mixture enrichment.

[stuart bowes]

captain hindsight to the rescue..

 

when you're taking stuff like that apart it's always worth taking loads of pictures from various angles as you strip it down, it can be really useful for reassembly 

 

there is a reasonably inexpensive book on SU carbs for maintenance and tuning and points of general interest https://www.amazon.c...s/dp/1855202557

Edited by stuart bowes, 26 March 2025 - 11:59 AM.