The T20 was equipped with a 247 cc
two-stroke engine, which meant that oil needed to be mixed with gasoline prior to injection into the cylinder. Simple two-stroke designs simply achieved this by requiring the user to combine oil and gas together (a solution known as pre-mix) before filling the fuel tank. However, in an advanced system like the T20, which was expected to operate for longer periods at higher RPMs, this would have been unsuitable. An excess amount of oil would be burned using pre-mix under these conditions, resulting in reduced performance and dirtier emissions, which in turn would cause the exhaust system to become laden with deposits, further reducing performance. The T20 solves this problem by incorporating a once-through oil injection system known as
Posi-Force, which consists of an engine-driven oil pump coupled to the throttle, which is designed to provide the proper amount of oil needed at the current RPM and throttle opening. The pump draws clean oil from a separate oil tank, and pumps it through hoses into the crankcase, where it is injected into the engine outside main bearing(s) and big end rod bearings of the crankshaft. Suzuki improved upon the system by adding oil injection directly to the cylinders on newly introduced models starting in 1968 such as the
T250,
T305 and the
T500. Suzuki would continue to use this system on many of their two-stroke motorcycle designs. Posi Force was renamed CCI (Crankcase-Cylinder-Injection) in the early 1970s and was used until the end of two stroke street bike production in the late 1990s. ==Racing==