I replaced the rubber manifolds yesterday and it solved my problem. A word of caution. When removing them, I twisted two bolts off in the head. The bike is old and they were all very very tight. 6 eventually came out, and the two bolts on cylinder #1 both broke and had to be drilled out and re-tapped (not a job for beginers!). I was lucky in that my drill had a straight shot at them with the engine still in the bike. Once this was done and the bike reassembled, I primed the carbs and it started right up. Bike runs much better now!