Converting from single to a dual seat

 Time has come to sell my CB750F. After crafting the bike's single seat design a year ago, I had to change a thing or two. Well, the buyer really wanted to have the option to ride the bike 2up, while still retaining the possibility to keep it as a single seat machine for his leisure rides alone.  He was looking for an easy way to change from one seat to the other, and that meant that the stock solution was out of the question.

To do this, I had to relocate the taillight and the rear turn signals, as they were attached to the rear cowl. This way, lights and license plate would stay attached at the same place regardless of the seat choice.
 
First, since there was no rear fender (the cowl acted as a fender), I had to make one. Fiberglass being the material of choice (no matter how much I hate working with it, it is pretty damn versatile as far as materials go), I laid down two layers of cloth with two layers of mat sandwiched between them.

 

 

 And after trimming all the excess off:

 

 Here is the fender mounted on the bike:

 Next it was time to come up with a seat design. I did not want the seat to look out of place on the bike, so I decided to copy the frame contours with fender and all. This is the first protective layer of duct tape (to make sure no resin would get where it does not belong), which was followed by a cardboard cutout of the desired seat shape, taped over and held in place by wire. 

 Here are the first few layers of mat.

 After trimming excess and shaping the sides of the seat pan to follow the frame:

 Followed by a quick sanding with 60 grit to provide for some "bite" and two more layers of mat. This one has five layers of mat and two layers of cloth. Plenty strong for two people.

 Final seat shaping (the front drops down more to accommodate for the gap between frame and side covers).

 I got the foam from two old seats I had in the garage (one was not long enough). Front section is nice plush, with rear being made of a firmer base (there is not as much material due to the rear frame crossbracket). The two pieces of foam were glued together, then belt-sanded smooth and contoured. The final shape was then covered in a 1/2" foam tro provide uniform appearance and hide any foam repairs I had to do here and there)

 And, a quick mockup with some white vinyl I had around. The buyer will be taking the seat to a pro upholstery shop for a white seat with green stitching.

The small rear fender now holds the taillight, while turn signals drop down from the frame on small brackets. To change from a dual to single seat, all that has to be done is to pop the side covers, remove two bolts (holding seat to the frame), replace seat, and attach rear cowl with two bolts. Total of 6 bolts and maybe fifteen minutes. Voila.