Won't stay running

I have an '81 Yamaha Sr-185 Exciter that had been sitting for a while and I just recently got it running after I replaced some parts and cleaned the carb. and gas tank real good. I then took it to a Yamaha shop to make some adjustments to the carb. and they cleaned it again real good. I've since then tested it out on the road a couple of times and it ran good. Except the last time I road it stalled at about 40 mph. I couldn't get it started again so I left it and went back to it about 3 hrs later. It then cranked up fine so I began to drive it back home. It ran for about 5 minutes and did the same thing. Any ideas on what could be causing this?

This is a possibility...
Make sure you don't have something like a rag near your intake that could possibly block your air intake to your carbs...This happened to me once whenI left a rag under the seat...It worked it's way into the air intake and chocked the carbs and stalled...I walked home and got the truck to go get it, when I returnd and tried it again, it started right up, but stalled while trying to get it up the ramp. Upon examining the situation, I found the rag laying across the intake...Duh!!
Like I said...it's a possibility, especially since you had it to the dealer and haven't had it apart since....