My XS400 Seat Build

[paultsmith]

I planned on making a fiberglas seat for my XS400, as I could not find any off the shelf that would fit and I was trying to do this on the cheap. I also didn't want to cut any of my frame and wanted to leave the battery, internal rear fender and everything else pretty much stock. This meant that I needed to make my seat a little longer than I wanted but, It seems to fit in with the size of the stock tank. Here are the pics and info from the build. Thanks to everyone on the board for help and ideas, as this was my first time with fiberglass.


I ended up cutting a piece of poster foam board and used this as my base. I also used green foam floral blocks, about $10 for all. I spray glued these together to get roughly the shape I was looking for.

I hacked out chunks of foam from the bottom to clear the internal fender and brackets.

I sanded the shape freehand using a sanding block. the foam was real easy to work with.

 

[paultsmith]

The next step was the fiberglass.

I covered everthing in Aluminum duct tape and put a sheet of aluminum foil over the poster board so the resin wouldn't eat the foam. I did a test earlier and the resin was going to eat the fiberglass.

I ended up laying 2x4s around the bottom edge of the seat so I would have some sides for my seat, rather than just the flat poster board

I used 3 coats of fiberglass, 1 layer of weaved cloth, a layer of chopped cloth and a layer of weaved cloth.

A rough trim of the fiberglass seat and mocked up on the bike. I used an air die grinder to cut off the excess

 

[paultsmith]

Next step was cutting the final shape and tail light hole and of course sanding/ Bondo/Sanding/Bondo/Sanding/Bondo.... paint/sanding/paint....

 

[paultsmith]

FOr the seat I tried just velcro'ing some exercise mat high density foam to the seat but it looked like trash. I then tried rapping the foam in vinyl, stapling it to the back of some small board and then putting that on the seat. Again a crap look was obtained, so I decided I needed a seat pan that I could wrap with 1 piece of vinyl.
Back to the fiberglass method, I also got the idea from this board to put in some wood strips so I would be able to staple the vinyl to the pan. To hold the pan down, I decided to epoxy (JB weld) some nuts into the pan and then run some bolts through the seat and pan to secure and hold down everything. For the pan foam I used a few layers, of different types of foam with a bit of spray glue in between the layers. It is very comfortable yet firm.

Since I painted the seat already it was necessary to cover it in aluminum foil before fiberglassing.

Trimmed and on the seat, ready for drilling the holes

Nuts in place

Seat padding & upholsetry work, again a first time for this. High density foam glued to have a flat surface

layers of carpet underpad

Covered with stuffing from a pillow

Completed pan

 

[paultsmith]

Finished seat

I covered the seat in some 4 stretch automotive vinyl from an auto shop and bolted the pan to the seat. The bolts really pulled the pan together and my seams and pleats were hidden when everything was tight.

Uderside of the seat. The seat is held by 2 bolts near the back end and snapped onto the frame using 2 cabinet type snaps near the front.

On the bike, again the seat is a little long, but this was needed to as I wasnt planning on cutting the frame or moving the internal fender.

 

[locOleoN]

WOW.. That is a great looking seat!!.

Congrats...

Im just wondering.. Wouldnt it have been faster and cheaper to bolt on a chopped back end of a tank to the stock seat pan?

Im really impressed!!

 

[valvesprung]

Yes but then it would look like you chopped a tank and stuck it on there ;D

Truly nice work mate, flows very well.

 

[forty4ma9]

Your seat looks absolutely great!

Thank you for taking the time to share your project! You did a spectacular job documenting and recapping the project. I love it when people share the details like this as it gives me some hope and inspiration.

 

[rawfish]

Nice build!!

 

[Swagger]

That's a damn fine seat, I don't think it's too long at all.
Anymore pics of the bike?....looks great!

 

[paultsmith]

That's a damn fine seat, I don't think it's too long at all.
Anymore pics of the bike?....looks great!

Thanks,
I plan on posting the build in the build section soon...
along with some more pics.

 

[Chivatty]

Awesome job! Gives me ideas...

 

[Giraffe]

First off I must say great job on the seat, Turned out great. We are currently doing the same sorta thing right now for a 72 CB350 with my cousin. I had a couple questions. If you don't mind me asking, How did you mount the completed seat to the frame, and what did you use to mount the License plate to the seat. Pictures would be great so i can sorta have a visual. This is both out FIRST bike project so this site is been a huge help for the most part so far..

Thanks Justin. Cheers

 

[paultsmith]

First off I must say great job on the seat, Turned out great. We are currently doing the same sorta thing right now for a 72 CB350 with my cousin. I had a couple questions. If you don't mind me asking, How did you mount the completed seat to the frame, and what did you use to mount the License plate to the seat. Pictures would be great so i can sorta have a visual. This is both out FIRST bike project so this site is been a huge help for the most part so far..

Thanks Justin. Cheers

Justin,
These pics should get you started. Let me know if you have any more ?s.
The seat is held in place by 2 bolts near the back and 2 kitchen latches near the front. The bolt holes were there on the existing frame and it is where the old passenger grab bar was bolted onto the bike. I just drilled 2 holes in the fiberglass seat, and used rubber washers on either side. The socket head bolts are big enough that I can screw them on hand tight and also makes removing them a breeze. To hold the front part of the seat down I used 2 kitchen cabinet latches, that snap and hold the seat down. They were real cheap but work surprisingly well. You really need to pull on them to remove the seat. I just bolted these on.
The seat rests on these and some round rubber dampers near the end of the but stop.

To take the seat on and off. I just place it on, pulling the seat through the tail light, then I screw on the 2 bolts and press/snap the front section.

Bolts on either side.

The front latch

For the tail light, I used some 3/4" angle aluminum to make up a bracket, then bolted it to the tail section. I used three pieces, 1 on either side, and then another that bolted across the 2 and held the tail light. I needed to bend this piece up a bit so the light would point straight back.
I was able to bolt the light and plate bracket to an existing bolt hole. The bracket holds the light and extends the plate past the seat so it can be seen.

 

[gribbs]

I love your hinge/latch idea. I might try something like that on my bike, as I have been struggling to find a way to mount the front portion of my glass seat/ Well done!!

 

[jay_kent]

Great work on that seat and pan. Great ideas for stealing

Jay

 

[jayellay]

great work, i’m stealing some ideas too. the kitchen latches are cool.

looks awesome.


Jay

 

[Chivatty]

Nice work! The latches are brilliant!

 

[tms325i]

How is the brightness on the tail/brake light? Looks exactly like the tail light I am interested in.

Looks Great!

 

[paultsmith]

How is the brightness on the tail/brake light? Looks exactly like the tail light I am interested in.

Looks Great!

The tail light isn't too bright. It is not DOT approved, but it is E-marked (european approved).
They are bright enough however and the brake is fairly bright too.