Tuning woes

If you've got the correct carb bodies for a Commando the pilot system should be bushed and wouldn't need screw in pilot jets.

I have seen bushed bodies with the pilot jet position threaded to take a jet, and with all the problems at Amal would it hurt to look?

Have I picked it up correctly your problems have started after fitting new carb bodies?

These brass bushes then must be well recessed into the body for a jet to be able to be screwed in on top of them?. I.ve built this engine from scratch . its not a rebuild, its built from parts (meticulously). I dont believe its electrical. but I have another set of 6volt coils and carbs on the way. if I cant sort the problem by then. I,ll see if there are bushes under the pilot jets.

Ok, no brass bushes in there, BUT, I checked the float level by removing, and bowls still connected to each other and with the fuel line still attatched and holding down both float shafts , then fill up the fuel line ,( you need about six hands) I noticed one float was about 1/16" or more below the basket face (no gasket) and the other one was level or just up a bit. I tapped down the brass seat only a few thou until the float levels were the same. If you go to far. you can knock it back up with a small punch. Well. it certainly is running a lot better, with better starting. Just need some more tuning.

I had the same problem on my Fastback; same cause - different symptom. The loose pin (due to groove worn in gasket) allowed too high of a fuel level in the bowl. But instead of a poor idle/mid-range, fuel would spill out through the tickler when the engine was running/shaking. Wouldn't leak a drop when parked.

My fix was to replace the gasket and to pinch the pin captive in the float bowl with a pair of needle nose pliers. If you pinch it slightly the pin will "snap" in and out of its groove in the bowl. also make it easier to check for float height when using the "hold the bowl up-side-down" method.

nbmBruce said:

May or may not apply to you: Check the float bowl gasket and make sure the float pin has not worn a groove in the gasket.

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Don,
I think you're looking in the wrong spot for the brass bushes; they are located in the bottom of the idle mixture screw bore, not in the hole where the older style pilot jets thread into. Pull out your mixture screws & have a look. The bush's bore is .016" - a bread wrapper twist tie (paper removed) fits snugly & clears the jet nicely.

Good Luck

Joe in St Louis

don said:

These brass bushes then must be well recessed into the body for a jet to be able to be screwed in on top of them?. I.ve built this engine from scratch . its not a rebuild, its built from parts (meticulously). I dont believe its electrical. but I have another set of 6volt coils and carbs on the way. if I cant sort the problem by then. I,ll see if there are bushes under the pilot jets.

Click to expand...