[FreakShow]

Working on carbs is like conducting a science experiment. In order to determine the true outcome/cause of a certain phenomenon it is vitally important to limit as many variables as possible.

Right now you have one massive unknown: Stalling around 50mph.
You also have numerous variables:
-dirty carbs
-diaphrams
-clogged jets
-air leak somewhere?
-fuel tank vent line clogged?
-a few that I may have forgotten

Basically, if you rejet now you're adding to the list of variables. Maybe a rejet will fix it. What if it makes it worse, OR adds an additional problem?

I just went through this the hard way with my buddy and his new-to-him '95 Suzuki GS500. We rebuilt the carbs and he insisted on installing new jets before we got the bike running first. A few weekends later we've got it running but wasted a CRAP ton of time because of setbacks caused by changing things before FIXING things.

Just my $.02. It's your bike to do with as you please. But be warned, if you rejet there is a chance you won't get it right the first time so be prepared to learn how to take the carbs out efficiently.