Starting problems with a XJ650

I am working on re-furbishing a Yamaha XJ650 for a buddy of mine and he mentioned that the bike has an annoying habit of not wanting to start. The bike has had it's carbs rebuild 3 times, had the seals, manifold, fuel, and jets checked and seen more service then open road. And still the bike will start sometimes. My buddy said that often he had to pop the fuel line off, and open up the bowl screw on the right hand carb and blow on the fuel line while cranking over the starter. The bike often fired up and then he would have to quickly re-attache the hose and close the bowl screw before the bike stopped. The bike didn't care if it was warm or cold out or if it was hot or not it just would refuse to start. I have read a few entries on here about this similar model but never read anything about how temperamental this particular bike is. I am at a loss and was wondering if anyone had any ideas on what might be the problem with this bike.

As some history about the bike, originally it was used in BC (Canada) and since was taken to Manitoba. I do not know if the bike was re-jetted for Manitoba or not. But now the bike is in Alberta and might need different settings again. I would really like to resolve the starting issue and get this bike back on the road, but need some direction to do that.