check you've got enough free play in the throttle cable, if its too tight it'll rev when you turn the handlebars or if the cable's pinched under something, such as the fuel tank, you should have a threaded adjuster either at the throttle on the handlebars or on top of the carb. have you tried screwing the tickover screw out a bit, when thats ok check that the carb throttle slide is not sticking you can hear a click when it hits the tickover adjuster screw, may also have an air leak in the inlet manifold but look into that if all else fails.
Chris P.Duck, April 2011
