Idles fine - then dies

[SteveD]

Try turning the mixture screws out an 8th turn...see what happens.

[Manfred]

Try turning the mixture screws out an 8th turn...see what happens.

I synchronized the carbs by pulling one spark plug at a time, grounding it to then engine, and tuned the other carb to faster idle possible by use of the idle mixture screw. Then the other side. Then adjust the idle to ~1,000 rpm with idle screws. Does this not set the mixture screws at the right spot?

[SteveD]

Yeah, it should I guess, but if it still has the surging, albeit minor, then a slightly richer setting might help. Doesn't hurt to try, and can always be put back very easily.

[pmonk]

Pulls strong on the main jet, but not so below? I think I'd clean the holes in the throat of the carb with some fishing line and follow up with a carb cleaner spray. The black dot on the right...

Didn't say if you tried this. Mine was stumbling bad until I ran some fine copper wire (I know) and cleaned these three tiny holes out. It would run on choke and part choke. Then stumble and sometimes die when trying to accelerate slowly. After engine was fully warmed It ran ok.

Course new pistons and valves did amazing things to the old bike.

[Manfred]

Good to hear from you, Paul. If I have time in the next few daze, I will do as you and Steve have recommended.

[pmonk]

you can tell when the the little passages are clear by blowing air into the fuel mix jet on bottom of carb. May try blowing out before running fishing line, wire or whatever through those little passages, i would think breaking anything off in them would be a big problem! I pulled my carbs apart 6 times before some kind soul suggested cleaning these passages out and solving my problems.

[Manfred]

I took them apart this evening (after replacing a dead battery on my car and will see how it goes tomorrow.

[Manfred]

A couple of days to and from work. Problem remains. Issue is with right side carb - when she's idling, I can pull up a bit on the left throttle cable and the engine responds fine; if I pull up on the right throttle cable, she hesitates and is slow to pick up RPMs. Idle mix on right side is about two full turns out. Idle is ~1,000 on the tach. Fully warm engine.

What would I look for considering the behavior of the right carb?

[Garnet]

Two turns out seems like a lot to me. What is the base setting supposed to be?

When I have a problem like that I allways retreat to basline settings on everything. Then check to make sure both carbs are working correctly, then balance and tweak the mixtures. If mixture scews and idle stops are much more than a quarter turn different from one side to another you have deeper problems.

[Manfred]

I agree - that was an incremental loosing up to see if the behavior would change. I went back to 1.5 turns out on both sides, idle at ~1,100. Right side still not right - will kill the engine about one out of two tries when I lift that throttle cable. The left side does not do this. And while sitting at idle - I detect a slight catch in the giddy-up before she dies. It's as if the right side quits once in a while and shuts the engine down.

Again - new gaskets, needles and needle jets in both carbs. No sign of air leaks into the carbs or intake manifolds.

Could a weak coil do this?