Stalls @ about 1800 rpm

[EZMoney]

Ok Gang now I need some help
Got my Mixed parts bike back together about a month ago and it seems to have a bit of a carb problem at 1800-2000 rpm.
it has an XJ motor and carbs.
It idles ok and runs like a top at 3000 and up but if you bring it up through 1800 it just dies. Quick rev will take you right through it but when you are pulling away from a stop if you are not careful it will die.

Checked all diaphragms ok
Idle mixture screws started at 1-1/4 and moved up to 2 turns in 1/4 increments.
still no change.
Carbs manually sync'd with bread tie, my icys tool that I made didn't work very well as the rubber stoppers got too hot and melted so I can't vacuum sync until I fix it.
Any Ideas?

[79XS11F]

I would not go digging around in there too much until you get the carbs synced but if I am not mistaken your likely looking at the beginning of the lifting of the needle jets in that range. If they were worn your would be getting too much fuel and if they are sticky they may not start moving upward out of the main jet until you give her a twist and draw in more air to force the diaphragms upward.
If you have not as yet given the carbs a REAL GOOD and proper cleaning it's time to do that as well. There's not much use in having them synced if you will only be removing them again to clean them.
Rob

[DiverRay]

EZMoney,
Don't forget, as you have the XJ, you need a YICS tool in order to balance the carbs!!

[EZMoney]

DiverRay
I built one of those tools from the plans found on this site and all worked well until I put soft tygon tubing on the tool as stoppers.
the tubing didn't hold up to the heat and when I pulled it out most of the tubing stayed in the housing I then had to make another tool ( I like to call a hook on a wire ) to fish the rubber out. When I get the right rubber I will try again.
The thing I don't like is that the engine doesn't just sputter at 1800 rpm it just dies, no bringing it back without a restart. Could it be electrical? Pickups look ok and on the XJ motor the routing of the wires has been changed from that of the XS and wiring doesn't appear to be the problem.