Motorcycle Repair: 1975 Honda CB200T carb problem, fuel mixture, float bowl

Question
I'm hoping you can help. This is going to be a little long, but I don't want to leave out something that may be important. I bought my 75' CB200T two years ago. It ran fine, but always idled at about 2,000 rpms. So, this year I decided to rebuild the carbs and clean the fuel system. I rinsed the tank with lacquer thinner-water-then rubbing alcohol, cleaned out the petcock and fuel strainer, then rebuilt the carbs with new Keyster kits, and soaked the carbs in Berryman's, and replaced the fuel lines with tubing from an automotive store. After I got everything back together the bike seemed to run great. I was able to get it to idle at 1,200 rpms and the pressure from the pipes was equal and steady. When I took it for a ride it seemed fine until I got up to about 30 mph, then the bike became sluggish. Then at 30 mph, I began to break for a stop sign. As soon as I pressed the clutch to down shift, the bike stalled. I came to a stop and after a couple turns the bike started and ran fine again. Again I got to 30 mph, tried to down shift and it killed (does this everytime now). I have removed the air cleaners and checked the action on the slides, checked the tension and routing of the throttle cable, checked for kinks in the fuel lines, started adjustments by backing the fuel mixture screws out 1.5 turns and the idle screws out 1.5-2.0 turns. I have also tried moving the throttle adjusters on the carbs up and down. I am at my wits end. Two more things: After running the bike, the right side float bowl is empty, while the left is full. And adjusting the idle and mixture screws on the left carb seem to make a lot more difference in the idle speed then when I adjust the left one(the one with the empty float bowl).  Also, should should the little notches with the indentations at the bottom of the carb slides face in toward the bike or out facing the idle screws.  I have them facing out toward the idle screws with the side that has the slot from top to bottom facing in toward the back of the carb.  Any advice is much appreciated.
Thanks,
robert stephens

Answer
Robert, some key things to check are:

Petcock internal passageways. Disassemble and run a drill bit into all the passageways, by hand, to ensure that there is no built up debris blocking the fuel flow to both carbs. When the fuel level drops below specs on either side, the idle speed will rise up all by itself.

Pull the gas cap and check for a blocked vent hole, just outside the edge of the cap gasket. Plugged gas cap vent holes will cause vapor lock inside the fuel tank and you will run out of fuel

Pull the points plate off, check the function of the spark advancer. You should be able to twist it against spring pressure and then it should snap back to retarded position. They often hang up and stick in one position or the other, restricting spark timing and advance functions.

The cutaways on the carb slides go towards the air filters.

I am not terribly fond of Keyster carb kits, as their calibration is often incorrect and the gasket material is not fuel resistant when you introduce alcohol into the float bowls.

Hope that covers everything.

Bill Silver