Throttle Adjustment

Giant-scale gas engines with Walbro-type pumper carburetors have spring-loaded throttle arms. This is a leftover from the engine’s industrial-use history, where the spring is used to close the throttle when the trigger is released (like on a leaf blower or chain saw). The carburetors are also equipped with a throttle-idle screw used to set the lowest rpm the engine can run. For RC use, these items can lead to excess battery draw, so it is...