RECO or Race Engineering was the manufacturing division of B.M.X. Products Inc.  Their model, the Racer~X was sold through motorcycle dealers as a private label brand.  This frame was a mild steel version of the mongoose with a small plate head tube gusset.

There are two versions of gussets, a single plate gusset with hole and a later "U gusset" at the head tube juncture.  These frames are highly sought after by collectors for their scarcity.