Big Tuna is finally complete. I’ve been riding it around for several days now and I LOVE it! So much torque for a 200cc engine! And it is tiny, like a mini-bike, yet very comfortable for my 5’10” 135lb frame. Quiet, easy as hell to ride, and very inspiring. This should make a great toy for someone. Here is a little before/ after action for you.
So I wired the bike today, and put some perforated metal around for trim.
Wiring is SO simple on this bike…no battery necessary! This is under the seat, completely wired. There are just two loose wires that will run out back for the tail/ brake light.
I replaced the old bulky stock coil pack that went under the original gas tank with two very compact new coils and mounted them on a bracket I welded up under the seat. Very pleased with the turn out.
Then I cut out some perf. metal to match the gussets I had welded in, and tidied up the seat loop.
Its the little things like this that take so much time. But it is also what I love the most! Lastly is a side shot, unpainted still because I’m waiting on the tail light to come so I can weld a mount for it. Then she’ll get a bath, and paint.
I know that when I was trying to do my first few upholstery jobs a few years ago I would have loved to find a blog where someone was doing exactly what I was trying to do. So, here is my best photo how too and advice for a custom seat. I’m no pro however…so take this with a grain of salt.
Once the seat has been cut, shaped, foamed, and mounting tabs finished, it is time to upholster!
First step is to cut the top piece out by tracing it around the seat, I usually give myself about an inch of lay room, ends up being even more since there is almost always a taper from the bottom of the pan (what I’m tracing) up to the top of the seat (what the top piece of material actually has to cover). But since I’m a noob, better to cut loose than tight.
Then I map the vinyl onto some pleating foam and cut that out too.
Pleating foam is very important for a good looking seat. it pretty thin… 1/4 inch I think, and not very dense, but the important quality is that the foam has a fabric mesh backing so you can sew it to the material and it will hold. Regular foam will tear and you could pull it right off after sewing it. This is what gives the seat a puffy and “full” looking pleat, diamond, or whatever your stitch design may be.
Next I take a dry erase marker and ruler and mark whatever design I’m stitching into the top. This one will be a loose diamond stitch. Loose meaning I’m using about a 1.25″ wide ruler to trace with. If I used a 3/4″ ruler my diamonds would be very small, both look good in my opinion. Now I need to set up my machine!
I’ve got a walking foot JUKI DU-1181N. The walking foot is the most important feature for a good upholstery machine. A regular machine will not pull the fabric through evenly at different speeds. But a walking foot presses the fabric from underneath and on top and feeds it through no matter if you’re hand walking it or blasting along at full speed (which is VERY fast!).
First I need to wind the bobbin. I’m using all black thread for this project. I recommend the upholstery thread that should be stocked at local shops in your area. Hancock fabrics always has it in black and white which is fine for me.
Sorry for a sideways pic, but you get the idea. That’s me getting ready to wind the bobbin. Then below is the bobbing and its holder, the bobbin must go in the right direction.
I know it is in right when I pull the string out and the bobbin spins the opposite direction.
Then I install the bobbin into the sewing machine bottom half.
Now I have to feed the thread through the machine, every model is different but similar. It is messy and goes all over the place,
Now I will oil the machine, which is done before every use. This machine is actually oil bathed. And sits in a steel tub filled with oil, and as I run the machine an oil pump circulates lubricating oil to the friction parts to keep it running quiet happily for generations.
All the little orange spots get oiled. Since they’re external, the pump doesn’t lubricate them.
Before digging into the actual seat, I always take some scrap and do a test run to make sure my adjustments are just right, it can’t pull too hard through either side, and I can meter the stitch width to my liking. Then it buzz through the pattern. A trick to make this go quick is to keep it connected. I did one direction of the diamonds all on one run, and then the other direction on another. This saves time and thread, as opposed to stopping after each run and resetting it over and over.
Now that the diamonds are done. I need to measure some side walls. I just measure half of the seat boarder, and add about an inch. The width depends on how thick the seat is. That’s just the width, plus an inch for the bottom to staple to the seat, and a half inch for the top to stitch to the diamond top. I cut two of these strips and sew them together. If you have a long enough piece of fabric, one strip can be cut. But I don’t…
This is the stitch I use to connect the two side pieces. Don’t remember the name, but it looks slick and is very strong.
You’ll have to search around for how that stitch is done like I did, forgot to take detailed pics of it in progress. Now below you can see the 3 main components that will become the seat!
At this point it is pretty straight forward. I set the diamond in place and trace with the dry erase the edge of the seat by bending the material over the edge and marking along it. Then I just start sewing the side to it following that marked edge. There is more flexibility in the fabric when stretching it to fit than you’d think, so I stitch it pretty tight. But if it is loose it is okay, you can run a tighter stitch over the old one, just wastes thread.
Above is a trick I learned for stitching around tight corners. To help avoid bunching I make little snips along the edge, not too deep! It really helps the material flex around the corner smoothly. Below is an example of my noob-ness…a good upholsterer won’t waste so much material… I don’t have an eye for my cuts yet.
I got curious about making a patch for the seat, I ended up not doing the idea, but may in the future. Here is a mock up.
I think it could look cool.
Anyway, after sewing the two pieces together. I test fit it, make any alterations to the seat or upholstery, and then I steam some water on the stove, set the upholstery over it for a bit to get it nice and hot. This makes the material very flexible and stretchy for the final fit. Then I wrap it snug, pulling evenly and stapling along the underside till it is done!
Almost forgot this step. See that stitch I’m pointing to? That is important to make the seat wrap smoothly, not show the stitches when pulling it tight, and it makes for a nice finished look. I wouldn’t make a seat without it. It is quite a trick to make a consistent line! But every one I do is better than the last…so that’s a good sign!
Well there ya go, that’s how metricmoto1 upholsters a seat!
Thanks for reading this far 🙂