Complex sentence: But while the main function of the second piston in a Beare Head engine is to replace the valve mechanism of a conventional four stroke engine, the M4 +2 take the principle one step further.
Split into simpler sentences: But while the main function of the second piston in a Beare Head engine is to replaces the valve mechanism of a conventional four stroke engine. The M4 +2 take the principle one step further.