250cc Modified Hydro (250ccMH), Also known a "A Mod" & AMH Displacment: 12.5 cubic inches up to 15 cubic inches. For Mark20H, (20 cubic inches Mercury engine with 1987 Stock Outboard specs) RequirementsMinimum Age: 14 years oldEngine: Swanson/Champion or American Hot Rod,"A" Mercury KG4H and Mark 15, or "converted" Mark20H Speed: 60 - 65 MPHMinimum Weight: 365 lbs.
