Thread: S 2A 2.25 with Solex Carb won't run without choke

Sounds like I was worried about something that wasn't even a problem when I put that filter in. I guess I might get a new piece of fuel line and remove it at some point then. The pump seems to suck air when I switch the pickup over to the passenger side tank, that could be because the level is too low or perhaps there is a hole in one of the lines. I'll investigate that later as what's in that tank currently smells more like thinners then petrol and driving around the farm I'm not going to be needing the extra capacity. I might remove the filter then.

The carb repair kit is on it's way so once that arrives I'll pull the carb back off and hopefully this will sort it out.

There is a little play in the throttle shaft still, is this something that's going to cause me problems or is it likely to be something that can be overcome with a little more mixture?

Cheers,
Rex

Stale petrol that smells a bit like turps can send you down all sorts of rabbit holes and waste time and money. Engine will never run properly on it. Put in fresh petrol and see how it goes.
Cheers,
Terry

Originally Posted by rexhunt

Sounds like I was worried about something that wasn't even a problem when I put that filter in. I guess I might get a new piece of fuel line and remove it at some point then. The pump seems to suck air when I switch the pickup over to the passenger side tank, that could be because the level is too low or perhaps there is a hole in one of the lines. I'll investigate that later as what's in that tank currently smells more like thinners then petrol and driving around the farm I'm not going to be needing the extra capacity. I might remove the filter then.

The carb repair kit is on it's way so once that arrives I'll pull the carb back off and hopefully this will sort it out.

There is a little play in the throttle shaft still, is this something that's going to cause me problems or is it likely to be something that can be overcome with a little more mixture?

Cheers,
Rex

Pull the pickup pipe out of the tank and check for rust pinholes or a split - these are common issues.

Unless very bad, the major issue with the wear on the throttle shaft is likely to be an unstable idle - you set the speed and mixture to get it idling nicely, and next time the throttle closes it settles in a slightly different position, and speed and mixture change. You usually end up dealing with this by setting the idling speed a little higher than the recommended 500-600rpm, which is likely to lead to running on and problems engaging first gear without waiting another ten seconds.

Yep, when I get to looking at that tank I'll start with checking that pickup, then go from there.

Sounds like the throttle shaft isn't going to be a problem then. Waiting 10 seconds to engage 1st from idle will be fine compared to what it does now, with the idle above 1k rpm.

Thanks for the help and suggestions so far.

Cheers,
Rex

Originally Posted by rover-56

Stale petrol that smells a bit like turps can send you down all sorts of rabbit holes and waste time and money. Engine will never run properly on it. Put in fresh petrol and see how it goes.
Cheers,
Terry

That tank is currently not selected, as the pump starts sucking air when switched over to that tank I'm not worried about it trying to run on old garbage fuel. When I get to looking at it I'll drain the fuel out of it and start with fresh stuff. Goodness knows how long that's been in there.

Cheers,
Rex

G'day All,

You mention there is a changeover valve for the two tanks. The port feed passages are really small around 4mm for my changeover.

They clog up easily particularly with rust particles. Suggest check these as well.

Chris

Ok, a big improvement today. It now runs without any choke. I put the new jets in and it will now run with the coke all the way in. It seemed like the pilot? jet was somewhat obstructed.

The interesting thing is that all but the accelerator jets are a different size to what was in the carb before. I didn't think to take my workshop manual with me so I can't compare to what it says they should be but that was interesting to find.

Unfortunately it won't idle reliably below around 900-1000 rpm which seems a bit high to me. If I slowly adjust the slow running screw then it will behave down to around 800 but any lower than that and the speed just drops and I had to open the throttle again to stop it from stalling. If I adjust the slow running screw so it stays happy, then open and close the throttle it just keeps loosing speed and will stall again. The workshop manual suggests that slow running problems could be caused by air leaks so when it's all cold I may spray some carb cleaner around the manifold to check there aren't any leaks there.

Also managed to notice a crack in the top tank of the radiator, just a slight weep for now but I'll have to get that sorted before much else happens.

Thanks for the pointers, things are looking up here.

Cheers,
Rex

The unstable idle is probably the throttle shaft not settling into the same place every time the throttle closes rather than an air leak. You could try a light spring that keeps the shaft pulled sideways so it always stops in the same position, and see if that allows a stable, lower, idle.