Custom motorcycles are works of art that are typically created from the wheels up. Nearly every component of the motorcycle can be modified or fabricated to express its builder's personality, including the seat. Seat pans are normally fabricated from bare metal or fibreglass, requiring the addition of foam padding and upholstery to complete the look. Padding and upholstering the seat can be done yourself with materials available from most craft stores.
Preparing the Seat Pan
Prepare your seat pan by sanding down the edges of the pan with a medium grit sandpaper to remove any burrs or points. Clean the seat with acetone or a degreaser to remove any oils and dirt that will interfere with the adhesive you will be using to pad the seat. Create a protective trim around the edge of the pan. This trim will protect the final seat cover from any sharp or jagged edges along the perimeter of the seat pan and will reduce wear over time. There are many options to creating this protective edge; many builders use vinyl weatherstripping and even long strips of duct tape. Whichever method you choose, work around the edge of the seat pan to build an even, rounded lip.
Selecting Foam Padding Materials
Selecting a padding foam for the seat pan is a key element to your comfort while riding. Ideally, your seat should have two types of foam: a denser, closed-cell foam for support and a spongier, open-cell foam for comfort. Closed-cell foam can be found inexpensively by purchasing a neoprene sleeping bag pad from a sporting goods store. Softer foam for the upper layer, such as polyurethane cushioning foam, can be found at larger craft stores. Cut the foam to shape using your seat pan as a template.
Padding the Seat
Spray the seat pan and the bottom of your dense support layer with a spray adhesive and let it set for a few minutes to provide a stronger bond. Attach the closed-cell foam to the seat pan and let it cure for at least one hour. You may need to weigh or strap down the foam to prevent it from lifting off of the seat pan during this time. Next, spray the top of the closed-cell foam and the bottom of the open-cell foam with spray adhesive, letting it set for a few minutes before positioning the new layer of foam over the seat pan. Let the adhesive cure again for an hour. At this point, the foam can be shaped with a grinder to round off its edges.
Covering the Seat
Creating a seat cover can be as intricate as your skill and confidence allows. However, for most DIYers this is the most difficult point of the job. To simplify the task, select a marine-grade vinyl from your local craft store and warm it up in a clothes dryer for five minutes. The warmth will allow the vinyl to stretch easier. Spray the seat foam with spray adhesive, letting it set for a few minutes before laying the vinyl over the seat. Select a point on the widest end of the seat and pull the vinyl over it. Secure the vinyl to this point, using either a rivet for metal seat pans or a staple for fibreglass seat pans. Work your way around the seat in a zigzag pattern, pulling the vinyl tightly over the seat and securing it before working on the opposite side. Apply heat with a blow dryer to help the vinyl over tighter spots. Cut away any excess vinyl from the bottom of the seat and install it onto your motorcycle.