Just bought a 1978 cb 400t...I´ve cleaned the carbs..new plugs...and it will start and idle fine, but will not take throttle...the boots are good and tight...the left side pipe gets red hot and the right side pipe blows cool exhaust...pops when throttle is added...there is an exhaust leak on the cool side....would that cause this? or if you can give me some advice here...i would greatly appreciate it..