Won't start after carb rebuild.

[UncleMike]

They're called mixture screws. They should be set using the highest rpm method. This should be done on a completely warmed up motor and on the centerstand. This should be done before the vacuum synch.
Generally, setting them to about 1 1/2 is a good starting point.
Set idle to 1,000/1,100 rpm. Start at any carb. Slowly turn a screw in either dirction until you hear the highest idle. Fine tune. Reset idle to base with the idle adjuster knob. Repeat to the others.
What screw ("one of the screws") are you talking about that you tightened down and the bike died and wouldn't start again??

Sorry, yes. Mixture screws.

For the other, I'm talking about the three throttle screws I was adjusting for synch.

[Hoomgar]

Mike, I'll let the carb gurus walk you through the fine tuning. I wanted to comment on this though:

The starter was initially going like normal, turning over quickly, and then it suddenly got VERY sluggish, and would turn VERY slowly, almost threatening not to at all. The headlight and guages were still bright.

If the lights were still bright you should verify with a meter but it sounds like the battery is still charged. If so this is your starter motor. Check to make sure all it's connections and ground are solid and if this continues to happen then it needs rebuilt. Especially if it works better cold and gets worse when it is warm/hot. The brushes most likely need replaced. There are usually a lot of these going across eBay. Sometimes it is easier to just pick up another one but rebuilding is always better.

[UncleMike]

Mike, I'll let the carb gurus walk you through the fine tuning. I wanted to comment on this though:


If the lights were still bright you should verify with a meter but it sounds like the battery is still charged. If so this is your starter motor. Check to make sure all it's connections and ground are solid and if this continues to happen then it needs rebuilt. Especially if it works better cold and gets worse when it is warm/hot. The brushes most likely need replaced. There are usually a lot of these going across eBay. Sometimes it is easier to just pick up another one but rebuilding is always better.

I noticed a while back that it's a replacement from a 550, too.