This Instructable is about creating a new seat for my motorcycle, a 1975 Honda CB200T.
I picked up a trashed old seat on eBay because my current seat is in good condition, and there's no sense in tearing apart a perfectly good seat. Plus then I wouldn't be making my bike inoperable while working on this project.
The main reason I wanted to change my seat is to lower standover height, since I'm extra short. I also welcomed the opportunity to customize any aspect of my bike, since I am a motorcycle beginner.
To make this project, I used the following materials:
- Vintage seat - ebay ($89)
- Marine upholstery vinyl ($22/yd) (pencil case practice project)
- UV upholstery thread ($7) - Sailrite
- Fabric backed foam ($11) - Sailrite
- Spray Adhesive ($20) - Amazon/ hardware store
- Replica chrome trim ($23) - David Silver Spares
and the following tools:
- Metal scraper/spatula
- Utility knife
- Foam shaver
- Plastic drop cloth
- Wire brush
- Rust remover (I used apple cider vinegar and a vacuum bag)
- Automotive epoxy primer and its hardener
- Preval sprayer
- Eye protection
- Angle grinder
- Serrated bread knife
- Sewing machine
- Size 16-18 machine needles
- Paper towels
- Pattern paper
- Tailor's chalk
- Binder clips
- Heat gun (optional)
Step 1: Old Seat Teardown
The first thing I did when I received my seat in the mail is take it apart. I had to pry off the edge trim and cut around the rusted strap fasteners to free the cover from the foam. I found some long dead earwigs under where the strap had been I then pried the foam from the pan, and was happily surprised that it did not crumble apart. It is a bit moldy, but I'm choosing to ignore it!
I found quite a bit of rust on the side of the pan that had been touching the foam.
Step 2: Remove Rust
I had a bunch of apple cider vinegar left over from a failed brewing attempt, and so chose to soak off the rust to use it all up. I wrapped the seat in an old t-shirt to protect the vacuum bag from the sharp edges, and sealed it up for two weeks.
The rust dissolves into a sort of sludge you can then wire-brush and wipe away. If I had access to one at the time, I would have used a sandblaster to get into every nook and cranny, but I'm still pretty happy with the improvement.
The strap fasteners were totally seized, so I used an angle grinder to cut off the straps.
Step 3: Paint the Seat Pan
I cleaned and dried the seat pan to prep it for painting, and taped off the rubber parts and other bits I didn't want getting clogged with paint.
To work with the epoxy primer, you should put on the following safety gear:
- long sleeves
- bandana to protect hair
I hung the seat from the ceiling and mixed the epoxy primer with hardener up according to its label's instructions. I put it in the preval sprayer and applied two coats 10-15 minutes apart, then allowed the pan to dry for 24 hours (after which it pretty much stops giving off fumes).
After the pan is primed, you can apply whatever kind of finish you want, including cheap-o spray paint. The primer will keep the pan from rusting any further. I chose not to paint mine, since so little of it is visible, and only under the seat when it's open.
Step 4: Shape Upholstery Foam
The first step in shaping the foam is to mark some guidelines on the foam using a ruler and marker. I marked one line for my first cut, and another for the beginning of the rounded edge. I made straight rough-cuts with a serrated bread knife, though I’ve also seen folks get great results with electric turkey cutters. I’m saving the bigger slices for filling in the gaps on the sides.
I got one of these foam razors online, and used it to even out the rough surfaces and shave down the foam more precisely. Since I’m new at this, I did a lot of the work with this tool because it didn’t take off too much material at once, so I could assess my progress easily and frequently. You can always take off more foam, but it’s harder to put it back if you make a mistake.
I didn’t try too hard to get the rusty bits off the underside, but did a cleanup with a wire brush. The underside of my foam was molded to the shape of the seat pan so I didn’t want to compromise that shape too much, and the epoxy primer on the seat pan should keep all that rust out.
Step 5: Assemble Seat
Before affixing the foam, I reattached all the plastic and metal hardware I removed at the beginning of the project.
To join the foam to the seat pan, I used super 77 adhesive. I filled in the gaps where the strap fasteners were with some small pieces of foam cut from the leftover slices.
Step 6: Sew Waterproof Vinyl Cover
My technique in pattern-making and sewing this cover are based largely on a video I found by Sailrite, which is also the vendor from which I ordered most of the supplies for this part of the project:
Before attempting such a large project with these new materials, I a pencil case as a test, which gave me confidence that my home sewing machine could tackle the seat cover.
I made a sketch and drafted a pattern by tracing the shape of the seat onto some gridded paper. I even used the old cover as a guide for drafting the piece that wraps around the back and sides of the seat.
The basic idea is to spray glue the back of the vinyl to the foam side of the fabric-backed foam, then stitch channels to create that lobed effect before joining all the pattern pieces together.
Since my home machine’s stitches looked better if I sewed it from the right side, I used a washable tailor’s chalk to mark these parallel lines onto the vinyl. If your sewing machine works well sewing with the vinyl on the bottom, you can just use a marker to draw the lines.
I sewed this complete cover and thought it came out just ok. While my sewing machine was technically capable of stitching these materials, I wasn’t getting the most consistent feed rates or thread tension— since I have access to the lab where I teach at SVA, I headed there to whip up version 2 on their industrial Juki.
I used small binder clips instead of pins to hold the pattern pieces together before stitching, and also to the pan while fitting.
I used a heat gun to soften the vinyl ever so slightly when it came time to fold at a seam or wrap tightly around the pan.
Step 7: Attach New Trim
I ordered this reproduction chrome plastic trim online and it works by pinching the upholstery to the metal seat pan while the metal clips on the inside of the pan grip its groove. Not only does this trim look great and just like the stock seat, but it’s also it’s an easy way to semi-permanently attach the cover. Although I wrestled with the process of putting on the trim, I still think it was more pleasant and reversible than using rivets or screws.
Step 8: Install Seat on Motorcycle
Swapping the original seat out for the new one was just a matter of two metal pivot pins each with a washer and cotter pin. Overall I’m pretty pleased with my new motorcycle seat, and had a lot of fun working on it. After riding with it for a bit, both as driver and passenger, I can say it’s just as comfortable as the original, and helps get my short legs a little closer to the ground. It is forming creases where the material scrunches when I sit on it, so next time I might slope the foam a little more gradually there, or change the pattern to have a seam along the compound curve, or maybe use a thicker material.
Thank you for reading my Instructable! I welcome your feedback in the comments section below, and hope you'll post a picture if you use any of these techniques in your own projects!