Motorcycle Repair: CBX 1000 doesnt idle, cbx 1000, vacuum valve

Question
Jan, I just bought myself (finally!) a 1981 model. Seller said it runs nice, but it doesn't at all. It starts easily, but only on three cylinders and as it warms up, 5 or six are fireing. It dies when the rpm goes just under 3000, and it doesn't have any power when i drive it, even on higher rpm's.
My question is, -before I start putting money into repairs, does it sound like a carb problem? I'm considering to send the carbs in for re-build, although seller claimed they have been re-built only 50 miles ago, I'm not sure I trust the quality of the work. Also, peacock on tank has been replaced with an on/off valve and in-line diaphragm has been removed. Would that cause any problems?  

Answer
Hi, Congrats on buying a CBX.  It sure does sound like a carburettor problem, most people who clean CBX carbs will clean the primary and secondary jets (which are hardly ever clogged) but they do not remove the tiny slow-running jets which are pressed in, although on later model carbs they can be screw-in type also. and these are more than likely your problem.  You can find out more detail on the website www.cbxclub.com  The vacuum valve should not be bypassed since it cuts off the fuel supply when the engine is not running, which can prevent major engine damage.  As long as the on-off valve allows enough fuel to flow, it should not be an issue.  Good luck,  Jan