My black bike will do that I changed the cylinder base gasket and slobbered silicone on the carb I'm either chasing a very small air leak or my float is set too high(need to check it) can't pin point the source might be the top of the carb or the carb slide is maybe catching in its bore put the bike on the side stand and it idles lower stand it up and it idles faster then will slow down. I'm pretty sure it not being caused my the new cable but then it might be. I need to look at the darn float this is the engine that's been apart a bunch of times new gaskets every time it will rev like a scalded dog. I just decided screw it I'm going to ride it tired of chasing the idle around. All the other bikes are behaving so the black bike is throwing a fit.( it don't like the new bars?) I'll find it sooner or later I put on a different set of handle bars from drag bars to I guess bmx bars now I can sit up right and it handles better now I feel brave enough to wave when someone waves at me. with the 36 tooth rear sprocket it will go too fast. not a scared with the new bars still not going to go wot no need to I'm not on a time schedule. I'm going to maybe make a rear rack for going to get things something simple and easy to build. hold at least a gallon of milk and other necessities. 
me and the bike
norman
me and the bikenorman