Air cooling mechanism for internal center of internal combustion engine

An air cooling apparatus for an internal combustion engine having heated parts heated by operation of the engine and an exhaust system including an exhaust muffler comprising:

• at least one air cooling jacket around at least one of the heated parts of the engine in heat exchange relation with said at least one heated part;
• an inlet for said at least one cooling jacket for introducing atmospheric air into said jacket;
• an outlet for said at least one cooling jacket for the discharge of air therefrom;
• negative pressure generator means in the exhaust system connected downstream of the muffler for receiving engine exhaust gas flow from the muffler and thereby producing negative pressure, said negative pressure generator means further comprising at least one ambient air inlet means communicating with the exhaust gas flow for utilizing velocity of said negative pressure generator means relative to the ambient air to enhance the negative pressure generated;
• and
• discharge conduit means having an inlet end connected to said cooling jacket outlet and a discharge end connected to said negative pressure generator means downstream of said ambient air inlet means, so that negative pressure produced by said negative pressure generator means draws air through said at least one cooling jacket inlet, said at least one cooling jacket and said discharge conduit for cooling said at least one heated part of the engine.