OSM72106910 OS Engines M2004SC 85mm Manifold, Tessmann B21

This is the O.S. Speed 85mm Exhaust Manifold Assembly. COMMENTS: Longer manifolds such as this one allow the main needle valve in the carburetor to be set lean for lower fuel consumption, but the needle adjustment becomes more sensitive. Care must be taken not to damage the engine by running it too lean. jxs 05/17/17 ir/jxs