It has been awhile since I have posted the progress made on the 65 Revive CB160 cafe racer build. Things have not slowed down and lots of fab worked has taken place. It’s a slow, but enjoyable, process and much time has been spent staring at all the angles and mentally engineering the game plan.
Up to this point I had the exhaust under control and it was time to turn my attention to the seat. I was dreading this section simply because there were many factors to consider and everything needed to tie in together. After much work I am happy to say that it appears to all be coming together. I am retrofitting a fibreglass solo seat to the bike. The rear frame hoop was going to need to be build and then all the electrical components would have to get hidden under the seat.
I’ll run you through the details using the following pictures. Much of the fab work never got photographed this time round simply because I was concentrating more on the job at hand then the blog. Anyway…the following gives you the highlights.
This is what I am starting with. Here is what the CB160 looks like, bone stock, under the seat. I planning to cram a lot into this space.
The fuel tank mount is going to interfere with the seat placement. In order to maintain the look of the bike the seat has no choice but to tuck up clean to the tank. This means the factory tank mount will need to be relocated.
As I have collected parts for the CB160 I added an 180 degree seat hoop onto one of my orders. I wasn’t sure if I would use it so I decided to trim off the rear frame tabs and tack it into place to get a visual.
I think it is fairly evident from this shot that the seat hoop will NOT work. I kinda figured so since the seat lines didn’t appear to be even close to the hoop lines.
Looks like I am going to have to try and build a seat hoop to fit. The plan is to bend a section of 7/8 pipe to match the shape of the seat. I needed to build a steel jig to wrap the steel around. I started by building a template of the seat hoop out of 1/8″ MDF
The seat pipe, that would need to be heated and ben,t was going to have to wrap around a fairly tight radius. The idea was to fill the pipe with sand first in order to prevent the pipe walls from collapsing during the bending. Since the pipe would be sealed during the heating process I wanted to ensure I had no moisture in the fill sand. I used some old baking sheets and heated all the moisture out of the sand using my powder coating oven.
I used a 7 foot section of thin wall 7/8 tubing and welded one end shut. I then filled the tube full using the dry sand.
The other end of the tube got a 3/4″ nut welded to it. I then used a 3/4″ bolt and threaded it into the tube to compress the sand solid.
Here is what the bending jig looked like before I put the heat to it. You can see the steel template I built to resemble the shape of the seat. I cut it out of scrap 3/8″ steel plate using the previously built MDF template as a guide. The steel then got tack welded to the bench and angle iron was clamped in place to help hold the steel tube in proper location. The next step was all about the heat. using a oxy-acetylene torch I was able to get the pipe to bend like butter.
And here you have it, the results of my bend attempt.
The hoop worked out fantastic. The wall collapsed ever so slightly however it will absolutely not be a factor. I was more then impressed with how well the whole procedure turned out.
I trimmed the seat hoop up to proper length and then built some solid steel frame plugs to help secure the hoop to the factory frame rails.
Frame plugs in place and ready for the hoop.
The hoop was TIG welded into place and the frame ground down smooth.
I am fairly critical of my work but in this case I would say the fit is near perfect. The lines of the seat fit beautifully along the new frame hoop.
Another picture showing the fitment of the seat to the hoop.
I had bought a rear rock guard to help keep road debris away from the engine. Before I could build the seat pan the fiberglass rock guard required some trimming in order to allow for pan placement.
First step in building the seat pan was to create an initial template using a cereal box.
Once I had my cereal box template I then cut out a plasma guide template from 1/8″ MDF. Here the template is clamped to the seat pan steel and ready to get plasma cut.
Some minor bending on the press gave it the right angle to allow it to snuggle into the frame rails.
The seat pan fitment worked out great. Eventually it will get welded all the way around the frame however more fab work is needed first.
This next picture may not look like much but the work actually took many hours. Much of the bikes life line systems need to be hidden from sight therefore mounting options are limited. Most of the systems will be hidden under the seat. It took hours of staring and planning to come up with a mounting sequence that would work. Even ended up doing multiple “re-do’s”
And here is the gist of it mocked up. The components that are now mounted under the seat include the battery, starter solenoid, fuse panel, power supply relay, license plate lights, charging regulator, ignition module, seat mounting posts, and wire management studs. It fits!
Here is another angle of the set up. You can se the 4 aluminum posts that support my seat. The posts thread onto 8mm studs and therefore I am able to unscrew them and machine them down on the lathe in order to allow for precise seat fitment.
I bought a lithium battery for the bike which allows me to mount it any way I want. Here you can see the power hook ups I built out of aluminum. To the left is the one side of my 2 piece custom license plate light I machined out of aluminum. In a few more pictures you will see what the light looks like from the exposed side.
I wanted to ensure I could remove the seat without any tools so I machined this knob out of some scrap I had. It is weighted very nicely to allow for quick spinning on and off.
Here is the rear underside of the seat pan. The license plate light housing will eventually get powder coated black. The tab to the right of the light is my license plate bracket holder.
This is what the underside of the seat looks like. I built steel plates to fit precisely on top of my aluminum posts. The center section is my seat hold down.
Here’s an overall view of the rear tail section showing the fitment of the seat to the frame rails, the installed brake light and how the license light and license bracket is tucked up underneath. Super clean.
The seat hold down knob sits in the center section and does not protrude below the frame rails therefore is hides out of sight but is still very accessible.
Final shot with the seat mounted, adjusted, and secured with my power distribution hidden away. It was a long process however highly successful.
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