Motorcycle Repair: 1971 sl175 starting issues, bill silver, advancer

Question
I have a 1971 Honda sl175.  I've been restoring this bike for a while and a couple days ago made an attempt to start it up. It turned over and ran for about 20 minutes then it died.  It wouldn't start for the rest of the day so I decided to let it sit overnight and I'd try it again.  It started the next morning for a shorter period of time and hasn't started since.  It'll start with starting fluid and then once that's burned it dies.  I've cleaned both the carbs and replaced the fuel lines so I'm kinda stuck on what could be wrong with it.  the fuel petcock looks to be in good shape so I'm wondering what the problem could be?  Any help would be much appreciated! :) thank you.

**Side notes: battery was replaced, new spark plugs get a good spark, I mixed a little(about 1/10 of the bottle) carb cleaner fuel additive to the fuel.

Answer
Tyler... sounds like the same problem a guy called me about the other day.....   Carb slides are in backwards.. left in right side, right one in left side. The cutaways go towards the air intake/air filters. Otherwise, the engine gets no air at idle, just sucks a lot of fuel, which then fouls spark plugs and every thing comes to a halt.

You didn't let it idle for 20 minutes did you????  

Make sure that the valves are adjusted, the ignition timing is set so the points open at the F mark alignment and the spark advancer is moving advance/retard, as designed. Clean/replace fouled spark plugs.

Bill Silver