LEAN BURN

The answer is yes when an engine is significantly de-rated from its maximum designed output.

Tohatsu's M2.5A is a prime example. In uprated form its WT47B power head developed 3.5 brake horsepower at the prop, but as the M2.5A had only 69 per cent of this output the carbie was set to run much leaner than the M3.5A, which was originally released in 1975.

Introduced to the Aussie market in 1988 the Japanese-made direct drive M2.5A was imported by Lakeside Marine, the national Tohatsu distributor, up until 2015. Its WT47B power head was also used in the Mercury 2.2 released in 1985, the Mariner/Mercury