The throttle serves no purpose on these models at all. Even when working properly, there's only about 600RPM variation in the speed. If it's really important to you, just ensure that the speed control lever on the engine is not bent from being run under a bush or whatever. It is supposed to tension/release the govenor spring. If bent, it will move, but make no difference to the spring tension, hence no change in engine speed.
New low-end machines have fixed-speed engines, which says all you need to know about what good they are.
phil_saunders(a)bigfoot.com
Phil Saunders, May 2009
