[PDF] Owner’s Manual - American Honda Motor Company This owner’s manual is considered a permanent part of the engine and should remain with the engine if resold. The information and specifications included in this publication were in effect at the time of approval for printing. Illustrations are based on the GX270 LPG. Honda Honda GX390 Manuals View online or download Honda GX390 Owner's Manual. Sign In. Upload. Manuals; Brands; Honda Manuals; Engine; GX390; Honda GX390 Manuals Manuals and User Guides for Honda GX390. We have 16 Honda GX390 manuals available for free PDF download: STORING YOUR ENGINE 13. TRANSPORTING 14. TAKING CARE OF UNEXPECTED PROBLEMS 15. FUSE REPLACEMENT 15.