How (not) to make a DIY seat for a motorcycle/ATV

For my This Old Three-Wheeler project, a 1973 Honda ATC90, I needed to make a seat. I didn't care much about looks, I just needed something function and inexpensive. That's why I decided to try and make it myself. For my 1974 Honda CL200, I had a hot-rod upholstery shop make the seat and they did a terrific job and the seat is gorgous. This seat, however, is not.

I found some used foam at work, they where used in the packaging for shipping a rack server. The white foam blocks are extremely stiff. This is good because the seat needs to be good and firm, regular seat-cushion foam would be too soft, but the foam I found was maybe too hard. The black pieces of foam are nice and soft though so I could put those on top to make it a little more comfy.

And I ordered a vinyl seat cover from Ebay, make specifially for a Honda atc90.

homemade motorcycle atv dirtbike seat

I first cut the big white foam blocks to shape and secured them together with duck tape.

They weren't quite wide enough though, and there needed to be a bit of foam that wraps lower around the fiberglass fender/seat pan. So I found some more foam, cut them to the right shape, and taped it all together. 

homemade motorcycle atv dirtbike seat diy honda atc90

Then the soft foam went on top. Why did I put the egg-crate shaped side up? Why?? I don't know why, maybe it was the beer, but I wish I did not do that...

Now I began stretching the seat cover over the foam.

And then used lots of duck tape, lots and lots of glorious, redneck duck tape. 

Doesn't look half bad! Kinda lumpy, but I've seen worse.

I wasn't done yet though. I needed a way to secure it to the seat pan. My first grand idea was to put long bolts going down through the bottom layer of foam only, with washers to keep them right in the middle between the two big foam blocks. Then I could just bolt it to the seat pan and be done. If only I had thought of that before taping everything together. With the duck tape being as strong and sticky as it was (Gorilla Tape brand) and with some of the foam being old and crummy, I thought that if I tore all the tape off and started over then it would rip the foam all up and I'd really have to start all over again. Not a good idea.

So, instead, I cut out a piece of perf board and glued it to the bottom of the seat. I used Goop brand glue and I also had a tube of "marine adhesive", but I didn't know which one would work better so I used both! haha

I splooged it all over the bottom, layed the perf board over it and then put big weights on it to hold it down over night. In the morning, the Goop was good and dry but the "marine adhesive" was not. Goop was the winner.

Then I just drilled holes in the fiberglass seat pan and screwed the seat down to it with sheet metal screws, making sure the screws had good hold of the perf board on the bottom of the seat.

Finally, last step. I used "seat mounting hardware" (for lack of better words) to tighten up the front side areas. I got the hardware from the old CL200 seat that I didn't reuse, they're chrome buttons with two pins sticking out the backside so that you can pin them down inside the seat pan.

homemade motorcycle atv dirtbike seat diy honda atc90

Not bad!

Not great, but, not bad either...

homemade motorcycle atv dirtbike seat diy honda atc90

And so there you have it, that's how (not) to make your own DIY motorcycle/ATV seat.