Can't get bike running right!!

Finally got it started......not running good but it did start. Had it on a battery charger overnight and tried starting it this morning......usual one bang and then nothing! Tried one more time, choke on, throttle fully closed..one bang and then it actually started. Took the choke off and it died instantly. It refuses to run with the choke off. Throttle response isn't perfect but not really bad, tune up should fix that .Thinking back to this Spring when I first tried to start it the choke was REALLY stuck, just about bent the lever trying to get it to move. I'm thinking I probably did some serious damage. Hard to believe the problem might have been that simple but that's often how things go for me.

Mine is running lovely at the moment. No way it will idle when I first start it and take the choke off. I keep it running with the throttle. Usual first start regime, for me, is: get fully ready to ride off, choke on, start (always no throttle), straight away I take the choke off applying throttle to avoid it stalling and ride off gently. By the end of the lane, about 1/2 mile, the bike will usually idle by itself. Not a nice warmed up idle, but it doesn't stall.

Have you confirmed if the trispark is indeed the right one for rotation direction of the commando camshaft? The previois trisparks were rotation direction specific, latest ones can be set up for either direction. Condition/type of coils being used? Trispark has a different spec resistance on primary coils than stock points setup. See their documemtation. Recall that a good spark at cylinder side is not necessarily valid for a plug under compression in the head.

Maybe a slide has fractured .

Have you pulled the carbs apart and inspected? I was having all sorts of problems with my Aermacchi, I finally pulled the carb apart (Dell'Orto, similar to an Amal) and found the choke lever had worn to the point where it would not turn off and the mixture was always too rich. Also, the main jet was really worn. I have replace bad parts and rebuilt.

Torontonian said:

Maybe a slide has fractured .

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Been there. Done that.

nortonmargie said:

Have you pulled the carbs apart and inspected? I was having all sorts of problems with my Aermacchi, I finally pulled the carb apart (Dell'Orto, similar to an Amal) and found the choke lever had worn to the point where it would not turn off and the mixture was always too rich. Also, the main jet was really worn. I have replace bad parts and rebuilt.

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How do you determine "really worn"?

nortonmargie said:

Have you pulled the carbs apart and inspected? I was having all sorts of problems with my Aermacchi, I finally pulled the carb apart (Dell'Orto, similar to an Amal) and found the choke lever had worn to the point where it would not turn off and the mixture was always too rich. Also, the main jet was really worn. I have replace bad parts and rebuilt.

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Have been told by mechanics concentric main jets rarely wear, but needle and needle jets do wear. There isnt much if any contact of needle with main jet bore.

Tornado said:

Have been told by mechanics concentric main jets rarely wear, but needle and needle jets do wear. There isnt much if any contact of needle with main jet bore.

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True and the needle does not come close to touching the working part of the main jet. However, wear/worn is probably not the best choice of words for the main jet. AMAL concentric (and her Aermacchi) main jet(s) can have the hole open up over time due to corrosion and/or grit in the gas and look worn.

Pretty sure her point was to go over the carbs and find out what is wrong - the pilot circuit (at least) is clearly not working correctly!

Followup: When I said "worn" the entry hole to the jet was oval and dish shaped and the needle was rattling in the hole. With both replaced, the needle fits smoothly, and does not rattle. Greg is right - my point was disassemble and inspect, not that the OP's problem was the same as mine.

Also blow out circuits with compressed air and/or carb cleaner - the passages may be gummed up

kommando said:

On Amal's the pilot jet has to be drilled out, its a small jet and no amount of carb cleaner sprayed down the pilot jet will get the jet back to size. I can't see any other similarly sized jet acting any different. So either get a new pilot jet or find out the drill size to drill out the current one. A 25 Amal flows 25cc of petrol in one minute and is a 17 thou hole and you use a 16 thou drill to clean it out.

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The actual size of the pilot jet is 0.016 inches on a 750 cc engine and can be cleaned out with an "A" guitar string preferably 0.015 inches or less. I would not recommend "drilling out" the jets especially with power and by hand as you will surely increase the size of the orifice by doing that. The bike has a 34mm Mikuni and the pilot jet on that carb can be easily removed to be cleaned. The Amal 930 is pressed in. I have both the original Amals from my 1970 and also a 34 Mikuni that I have been swapping back and forth the last few seasons. The Amals always performed better and plugs were good colour but your hands must always smell of fuel. You get NO gasoline smell with the Mikuni but the carb is set too rich when you buy it new. I was told that they do that on purpose so your engine does not overheat.