Dynamite's Large Scale Safety Kill Switch allows you to shut off the engine from a button you assign on the transmitter. 

Features:

• Works on any gasoline engine, with a magneto drive ignition (not compatible with CDI driven ignition)
• Remote LED to indicate if the ignition is live
• Fiber optically coupled to eliminate interference
• LiPo/LiIon/LiFe/NiCd/NiMH compatible
• Voltage input range from 3V - 3A to 20V - 16A
• Surface mount technology
• High quality wiring with universal servo connectors
• Only 0.3 oz/8g
• Manually shut off engine from assigned button on transmitter
• Automatically shuts down power to the ignition on loss of signal or low voltage