XJ 750 jerks and sets out to…

If it only runs on three cylinders, then it suddenly pulls off at full throttle to expose itself immediately to it. All float chambers fill up, I tried that, the carburettors are supposedly ultra sound cleaned, at least externally pieksauber, however, this has made a Yamaha – dealer, not myself. Before I take them apart now and shell them myself, maybe someone has an idea, the same experience, it is what banal ? spark plugs are new, filters are also. And: W as have the six (!) black hoses for a purpose that disappear from the gasses in the Nirvana in front of the battery box (and are nowhere connected)