1978 CX500 Scrambler Build

Now comes the hard part, which is deciding which direction I would like to go. Obviously it's already headed in more of a scrambler direction. I tend to like this, and might just keep with it. It will probably have some pretty strong cafe racer aspects to it however. I have looked at a lot of builds in the last few days, and have found some that I really like. Basically I might steal little ideas for each and try to make this build my own. Imitation is the best form of flattery, 'amaright?

I'm sure just about everyone has seen this build before, but I really do like how clean it is. I like the rear disc conversion, and how the front forks really pop. I also like the painted engine with the heat fins grinded down to be shiny. The way the rear fender extends on this one is pretty sweet as well, tho I would make it match the tank. Very curious about what seat they used, or if it was a custom job. And this is probably my favorite exhaust I have seen, although not really a scrambler type. Hence, I might be going a hybrid.

I like how the frame and coolant tube are a bright color on this build. Of course I am already thinking about color palettes at this point (how could I not) but that's getting a bit ahead of myself. It's an idea to be thinking about going forward.

This is another build that has caught my eye. I like the color scheme on it. (Not the palette, but the scheme). I could also see myself doing the rear fender/seat along these lines as well.

More to come.

Lastly (for now) there is this one. I actually personally know the gentleman who did this build. I like how the engine and tank match up, although I probably won't replicate this. But it is a fun build I thought was worth showing. The more I think about it the more I think I need to go with some sort of aftermarket shocks for the front.

I see there are two different frame types here. The first is different than the next three. Any insight on this? Clearly I'm stuck with the first design.

I have been playing around a bit with my superior photoshop (mspaint) skills. Something that will be very important is getting the lines right. I'm sure this could be easy to overlook, but I want to spend a bit making sure this is done correctly.

I see there are two different frame types here. The first is different than the next three. Any insight on this? Clearly I'm stuck with the first design.

Ideally red, green, yellop, and purple would all be parallel. I'm not sure if this will happen or not, but hopefully I can bias it that way.

I don't build anything just to be looked at. In fact, I have a personal distaste for things that are solely decorative. I love where form meets function. I work on motorcycles so I can ride them. Each bike I have has is ridden differently, and I thoroughly enjoy each one in it's own way. Some are comfortable. Some are exciting. Some just sound and feel fun.

At this point I haven't done a single modification to this bike. But boy it looks good.

The grinder is coming out soon. Stay tuned.

I have been thinking about color scheme and collecting parts. Here is one potential palette:

I ordered some used forks from a 2004-2005 CBR 600 RR. Some folks use Yamaha forks, but I just kinda figured that I would like to keep it Honda parts. 😉 They cleaned up very well with only a few minor scuffs remaining.

Next step: Take the old forks off of the front of the CX and see what it takes to mount these. I'm debating if I should make my town triple clamps or use the ones from the CBR600RR.

Okay, time to work on the Triple Tree.

The new one is quite a bit wider than the old, but also doesn't have the same forward offset as the original. I loosely mocked it up on the frame and determined the front forks will hit the tank without much turn angle if I use the CBR600RR tree. Meaning I need a new one. This is mostly due to the distance between the stem and the centerline between the two forks. I don't recall the measurements, but it's a significant difference. This will limit how far I can turn without hitting the tank.

Stock turn:

Max turn with CBR triple tees:

Looks like I will be making my own.

I found the center to center distance for the forks was 204mm on the CBR tree. On the CX stocktree the offset center to center from the stem to the forks was 54mm.

To do what I need to do next, I needed to press out the stem. This is scarier than it looks. I got everything lined up, and let the pressure build but it didn't want to budge. You will notice I ended up using my handle bars for leverage as I stood to the side. Finally CRACK and the stem would move just a little bit. It was super loud when it would pop and move. Scared the tar out of me each time.

I didn't remove the race bearing first. I just pressed both out at the same time. In case you are wondering, the stem needs to press down from the top and goes out the bottom. I didn't know this and had to look it up.

Sweet, sweet victory.

From there I got some measurements.

Then time to find my happy place. Don't be too judgy, this is still a work in progress.

Another note on steering angle: A stock CX500 will turn about 40.5 degrees off center before hitting the stop. If I don't replace my triple tees I will be limited to about 24.5 degrees.

I found an excellent article (post?) talking about front end swap stability. 

https://www.cx500forum.com/threads/front-end-swap-stability.67289/post-601161

With that in mind I'm going to set the distance between the centerline of the forks with the stem at 50mm and see how it goes. I redesigned my triple tee and here is my current working model:

I can 3D print these to test and mock up. Which is precisely what I'm doing.

For anyone reading along, you are now caught up to 3/12/2024. Any new progress you see will be posted as it happens.

I 3D printed part of the lower triple tree. This was on my fastest most blocky setting, so the print doesn't look particularly good but it will serve it's purpose.

Best I can tell I have about 41 degrees of rotation. I'll take it. Of course I will mock it up with the rest of the model.

I will start fabrication of the triple trees and soon as I have some machine time available. Right now I'm running parts for a big customer and can't take stuff apart to do fun stuff. There are some features I need to add to my 3D model such as end stops anyways.

I did order my bearings today. Hopefully they will be here in a few days.

Also, looking at the shocks side by side they are close to the same length. I started wondering today how they would compare sitting next to each other, and here's my answer.

While my CNC is whirring away making parts for another customer I can start on the design on the hub. I'm sure the existing hub could be adapted, but I think I would rather just make a new one from scratch.

The axle size on the CBR is 22mm and the original CX is 15. (IIRC, don't quote me here.) By making the hub myself I can use CBR bearings and size them to use the CBR brake rotors, and get everything to line up perfectly. Remember, I want to use the original Comstar wheels. This is just a first pass as I don't really have any good measurements yet as far as the spacing between the forks. I won't finalize this until I have my triple trees milled and my forks installed, but for now I can get it roughly designed.

I ordered some cheap bearings and seals from eBay.

I will also need to add features for the brake rotors. I will probably go with something like this. Yes, I could easily spend a lot more money on rotors but knowing where skimp and where to save is important.

After a half hour of Solidworks and one Red Bull we have a start.

Well...one thing lead to another and here we are. I have designed a very nice hub. Now I'm wondering if I want to go through all the time to make it. It's clearly the nicest option and I kind of want to see it through, so who knows. Please keep in mind this is just draft #2. I'm still waiting on a few dimensions once I have the forks installed and my rotors in hand. Then I came make things a bit more precise.

I'm debating. Right now the holes for the Comstar spokes are thru holes just like the original design. I'm considering tapping them and just installing them with a nice button head torx bolt from each side.

I tried to make it one piece, but I ended up having to compromise and make adapters for the rotors separately. If I had a lathe I could have made them into one piece, but I don't. I really wanted where the wheel attaches and both bearing surfaces to be one piece, and I accomplished that. It's also a bit heavier than I wanted at 4.76 lbs for the whole assembly. That includes the bearings and end spacers that go over the axle.

One thing I noticed...as far as I can tell the 47mm seal and the bearing are just stacked one on top of the other on a CBR600RR. Can anyone confirm this?

Here is a cutaway view to show how everything goes together.