With the bike completely disassembled, the frame was ready for modification. I managed to find a scrambler seat on gumtree which I liked that would fit the frame. Using this as a basis for the cafe racer, I got started on cutting up the rear section of the frame.
I cut off the section just past the top shock mounts, and grinded off unnecessary tabs such as the helmet holder.
I was a concerned about the frame’s structural changes with the rear end removed, and wasn’t confidence in my welding enough to know if it would penetrate through the full-gauge of the metal. As such, I went to a local motorcycle shop to weld in the rear hoop. In my opinion, for the price I paid they could have done a more meticulous job. In hindsight, I think I would have gotten a better product for cheaper going to a general welder, or simply doing it myself after some practice.
There were some holes at the top of the frame around the rear hoop junction that I filled in by using the MIG welder and sanding it smooth with a high grit angle grinder sandpaper.
To mount the seat to the frame, I also had to weld some cross bars which also had the benefit of strengthening the frame, which you can see in the left photo below. In another post, I also show the process I went through to fabricate an electronics tray. However, the rear section of the seat would be exposed to the dirt and grim from the tyre. As such, I welded some sheet metal between the two rear most mounting bars to act as a mud-guard.
The left image below shows the final result once I welded in the rear mud-guard section and grinded it to be flush with the cross mounts. Once this was done and some final sanding of the frame was competed, it was ready to be powder-coated
Vapour blasting and Powdercoating
After getting the frame back from the powdercoaters, the result was a nice, clean satin finish as you can see in the photo below.
The below leg image shows various parts before vapourblasting. Looking back at these photos, I actually did a decent job of cleaning these up (in hindsight, the vapour blasting could have done the final touches rather than me being a perfectionist with brushes). On the right are the parts after vapour blasting.
Below are the parts that I got powdercoated. There’s nothing quite like the excitement of getting fresh powder-coated parts back. Makes them look brand new!
Front Wheel assembly
Beginning with the front wheel hub, I had my local mechanic press in the new wheel bearings.
Next was cleaning up and drilling the front brake disc. I managed to find a drill pattern online and printed this off and taped it to the disc. From here, I used a drill press and clamps to initially drill the disc with a 3mm cobalt tipped drill bit (Regular drill bits wear too easily with the stainless steel). I then proceeded to a larger cobalt tipped drill bit and then countersunk each hole.
I then masked the brake disc and used brake caliper spray paint to paint the inner bracket of the disc brake.
From here, the front wheel hub could be reassembled. I put the speedo drive assembly on alongside the brake disc and used the 10mm bolts to bolt them together. Originally the CB550 used nylon nuts to prevent loosening, however I decided to use the CB500 tongued washers instead to prevent damaging the fresh paint on the brake disc.
I could then assemble the hub to the new aluminium rim using stainless steel spokes from Buchanan. I simply follows images of the wheel online and then equally tightened the spoke nipples. I tightened each spoke in small amounts until they all had enough tension. My gauge for this was based off the chime the spokes made when you hit them with a spanner. Seemed to have worked well!
Rear Wheel assembly.
With all the fresh rear wheel hub parts powdercoated, I could make a start on assembly.
Same as the front wheel, I had my local mechanic press in the bearings on both sides. I then placed in the rubber dampers that I cleaned, they were still in decent condition so I reused them.
The side plate could then be installed. I used a rubber mallet to press it in without issue. I used the same bearing retainer and screwed it in using the make-shift tool I mentioned in a previous blog post. I was able to get the bearing retainer to the correct torque and then used a nail punch to stake the thread.
The threads that held the sprocket on were also powdercoated so I had to remove the paint. To do this, I used a cotton bud and placed paint stripper on the threads. I also made sure to cover the rest of the hub with newspaper. From here I could then rub the paint off and use a metal brush to clean the threads.
The sprocket and cover plate could then be installed alongside the spacer. I also used a newer model lock-nut that removed the need to use tongued washers. With installing the sprocket and cover, I referred to the Haynes manual I purchased to tighten the nuts to the correct torque.
Another point, I purchased a new 34 tooth sprocket vs. the original 37 tooth sprocket the bike came with. This is because the output ratio of the CB500 is different to the CB550, which used a 37-tooth sprocket.
With the plate that holds the drum brakes on, I installed the new EBC brake pads and put the washer and cotter pins on the fixed end of the pads. The rear brake cam that I zinc-plated was also installed as seen below. New springs also came with the new brakes, which I installed with pliers.
At this point, the stainless steel spokes were installed in the same pattern as the front wheel. I used pictures on the internet to get the pattern correct and ensure I didn’t make a mistake. The image below shows the start of this process.
There are different angles of spokes provided that you have to correspond to the correct hole on the rim. Luckily it was easy to determine if you used the wrong spoke as it wouldn’t go in correctly.
I started off going around one lap of the rim and installing one kind of spoke in. From here I then followed the same process with the different type of spoke until they were all installed. It took some trial and error to get them in, especially as the rim and hub became less movable with the more spokes that were installed.
After installing the spokes the rear wheel was essentially finished. With both wheels, the spokes I bought were too long for the after-market rims I purchased, so they had to be shortened so I could install the tyre.
With spoked rims, you also have to true the spokes. This means you have to tighten the spokes so the rim is concentric to the hub, otherwise you get vibration as you ride. I bought a truing stand to do this, however I wasn’t quite confident in getting this right. So instead, I took this to a motorcycle mechanic and they were able to true the wheels for a good price.
With both wheels trued, I took both the front and rear wheels to a local tyre shop. They showed me the tyre sizes they had available and I chose the ones I wanted. The stock front tyre was quite small from factory, so I went with a slightly larger size to fit a more modern look.