When the throttle jams wide open on my Solex I can get 25kms an hour out of it.

Seems as though you lot have been having fun while some of us were away in a field...

Fwiw, the adjusting screw for the closing position of the secondary choke butterfly of a 26-35 Solex carb. has had 3 different arrangements.
On the first 2 instances, these were on the offside of the carb., then it moved to the nearside on the 3rd version.
Note that these have nothing at all to do with the accelerator pump cam, which is mounted at the offside end of the spindle for the _primary_ choke butterfly.

I'd guess that 5mm ball bearing is from the detent setup which holds the fast idle cam in the 'off' position, but not sure why the throttle has jammed open, unless the linkage between primary and secondary butterflies is worn or damaged...

ken

p.s. "the temp guage is staying at half rather than at 2/3"
Much more likely to be a voltmeter, especially if it's parked near to the fuel gauge...

ahhhhhhhh its the volt meter...I feel daft now! Cheers Ken.

The secondary choke butterfly was definitely jammed open, it was smacking against something very metallic, and yet just released itself in a second. Very strange. Does anyone think taking the carb off and checking it over would be a good idea? If its worn I'm tempted just to save up for a new carb, I want to do a lot of driving in it next year so might be worth it and keep the old one for bits.

The mad thing is, its running really well and starting first time, its bloody odd! I'm going to have find out where that ball bearing comes from, whether it is the detent ball from the gearbox I don't know yet.

Definatley not!

if it is the 2nd choke going over centre buy a tin of carb cleaner and scoosh it all over the outside of the carb till its clean, pay paricular attention to the bent coathanger wire actuating rod on the side if the carb is old enough to have that mechanism

then unhook the return spring from the lever at the carb end and re attach it to the pin that holds the trottle cable in.

the detent ball should be behind a plate on the choke spindle but 5mm sounds a bit on the big side

also check that the choke lever spring which is tiny is still there and that the hook on the end isnt about to break, bend up a fresh loop to locate it

that gives it a fighting chance
if it still does it try turning the plastic bushes in the linkages at the side around a bit and i also put a slight bend in the wire lever on an old carb efectivley shortening it

slapping on a new or recon carb is just throwing money off there isnt much to a fixed jet carb to go wrong and a re furb kit is relativley cheap
Sean

6.1mm on the carbs I've just checked?

ken

My first thought was that it was a detent ball, though I can't picture exactly where it should have come from. My second thought was that the spring behind the ball has probably met an unfortunate end in between the cam and the carb body, and caused the throttle to jam in the process...

Maybe this is the culprit? Looks like a ball on this diagram:

That's the one I mentioned in Sunday's post, isn't it?

If someone's been unscrewing bits of the carb and not putting it back together properly, might be worth checking that item 24 is still in place.
That's another part which often 'disappears' following such interventions.

ken

It probably is, I had no idea where or what the fast idle cam was though! Thanks for the help though will have a good route around when I can get chance, seems to be running ok though and I as I mentioned confusingly better than before.

On the side of the road in the pitch black a number of parts were heard dropping to the floor so could be other things missing as you said.

Does anyone do a repair/refurb or ancillaries kit for the twin choke solex? Can't seem to see one on Ecas and a google search brings up nowt apart from gasket sets.