Cobra CX65 Mini Moto

[toratora]

To properly adjust the spring tension I need to gain better access to the shock. To enable this I had to remove the subframe. Once there of course it became clear I didn’t have the proper tools. Still there was plenty to clean as that Arizona dirt is absolutely tenacious!


First the seat and side panels had to be removed.


The air box is connected to the subframe so in order to remove the subframe the coupler to the air box must first be loosened up. The there are four bolts securing the subframe. With those removed the entire subframe will come off.


The upper shock mount is freed up with a 14mm socket. The bottom end pivots freely making it easy to gain access to the spring adjustment ring. Sadly the ring is rather damaged, and needs replacement, plus I don’t have the proper tools to adjust it.


Even though I’ve spent a good amount of time cleaning there’s plenty more to work achieve. I imagine some of that dirt might not be discovered for years to come!


I also discovered that a number of rubber parts will require replacement.


With some effort things are cleaning up. Eventually all these little issues will be resolved. The bike is incrementally getting closer and closer.

[toratora]

Some Cobra parts showed up today. The clutch bits are still on the way. Fixing up this bike is a process. A very long and slow process!!

[toratora]

Today was another attempt to make progress with the Cobra!!


Ed came by on his way to work to drop off some spring tools. This was extremely kind of him.


Unfortunately the Cobra wasn’t in the mood for progress today. The spring adjustment ring is in very bad shape.

The plan was to remove the ring, and try replacing it with the rings from an Öhlins shock. There is a nylon set screw that keeps the ring from turning. Due to the damage on the ring this set screw is rather difficult to manipulate. I did try to remove it, but with very little success.

I continued by loosening the ring. This was going okay until I heard some grinding. Now I hard cleaned off the threads, but obviously I had missed something, The plan was to turn the ring back on a little bit, clean out the threads, and then continue on with the loosening. However, that’s when the tool gave out.

After that is was a case of putting the Cobra away, and getting out a Derbi on which to wrench!

I did talk with Catherine at Daly City Tool Mart. She said that she could re-pin the wrench. I sent Ed a message about it letting him know that I could take it over there, and get it repaired.

[toratora]

Once again it is time for some Cobra love. I visited Catherine at Daly City Tool Mart to pick up a wrench for the spring. But the problem remained being able to compress the spring enough to be able to tighten the ring. I was chatting with Kent over at the Moto Garage about it and he hooked me up with a spring compressor tool.

I also put some effort into cleaning some carburetors. I’m likely to be running a TM24 on the Cobra. Mostly because that is what I have laying around. Eventually I’ll probably fit a PWK on the bike, but for now I have some TMs, and should be able to get something working that way. Since the spigot, and air box connections are the same dimensions as the VM26 that came on the bike a switch to the TM should be fairly straight forward.

[toratora]

I am really getting beat down by this bike. I found out why the ring is stuck on the shock. It turns out the threads on the shock body are totally hosed. This was not visible with the spring on the shock, but once I was able to remove the spring it became obvious. I did try cleaning up the threads, and made some good effort in that direction, but I just can’t get enough leverage to spin the ring back and forth in order to be able to do much.

Kent’s spring compressor tool worked great. I did some reading on how best to use it. Everyone said to grease up the threads, and to use a wrench on the tool to hold it in place while tightening the screws, as this will help keep it from climbing up the spring.

[Rj_666]

So... new shock ?

I've never had much luck cleaning up threads on shock adjustments like this, they're so fine, they just cross thread hoplessly.

What shock you thinking of ?

[toratora]

Since there was no way to move the ring, and I’d very much like to start riding this bike I improvised. I took an oversized ring from an Öhlins enduro shock that I have, and employed it as a spacer. This still doesn’t provide enough preload, but it is better than what it was with out it. The spring has a number of 280 on it. I’ll have to look into what that actually means. It is quite possible that this spring isn’t up to the task at hand.

I put the subframe, and plastics back on the bike. Then did some more carb cleaning. Tomorrow I’ll install the carb, and see how the bike feels. Just sitting on it though it drops a lot, and that’s eventually going to need to be dealt with to get the bike to handle properly.

[toratora]

With the shock somewhat sorted for now it was time to turn to the carburetor.


Yesterday I did a bunch of cleaning, and things looked pretty good today. I did a little more cleaning, and then started on the assembly. Looks like the main jet is a 65.


The first problem I ran into was the cable not fitting into the top of the carb. A little time with Dr. Drill, and that was solved.


After that I could finish assembling the carb.


Next up was prepping the reeds and intake with some copper coat. Then fitting the carb. It sits in there okay. I’ll probably come up with some techniques to get it to fit better over time. For now it works. The choke is a bit difficult to reach, and of course there would be issues.

The bike started right up, and has nice power. It didn’t want to idle, but that had more to do with not being warmed up, and no choke (it is a little difficult to reach). The next issue is the float valve isn’t functioning. This could be a simple adjustment, but that will have to wait until I have more time.

[toratora]

Today was more carburation action, plus a little bit of introduction of the front brake lever to Dr. Force. First I looked at the jet that was in the VM26, and found that it was a 280. Based on that the jet in the TM24 must be a 165. Which is much smaller. Still the bike has a lot of pep. It’s going to be interesting to see what happens when I get it out to the parking lot for some testing.


I tried a number of things with the carburetor today. The main objective being getting it to stop leaking. I took the float valve from the VM, and tried it in the TM. It fit, and since they use the exact same float there was no problem getting the parts to match up. This stopped the leak, but caused a lean condition in the bike. Which is to say it wasn’t opening up enough to fill up the float bowl, thus not enough fuel. So I went back to the stock float needle, and made an adjustment on the float. This seems to be working, and will find out how much during the testing. At least the leaking stopped.


Another thing I noticed while working on the carb is that the shift shaft seal is leaking. That’s going to have to replace it fairly soon. And every time I work on this bike I find more Arizona dirt that needs to be cleaned off. By this time I would have thought I had gotten it all!


Next up was dealing with the brake lever. It was bent quite a lot. A little introduction to Dr. Force, and it became better. It could probably still use a bit more encouragement, but this did help a lot. Still the front brake is horrible. It is currently working better than it ever has since I got the bike, but it really isn't enough to stop the bike. It will be find for doing some testing, and drill this weekend, but I am going to have to figure out a way to get much better brakes before taking this bike to the track.

As noted previously the clutch master is seeping. I ordered a revision kit through Ed, even paid up front, but it has yet to materialize. So while progress is being made it is exceedingly slow. The good news is that I am becoming more and more familiar with the Cobra.

[toratora]

I guess I could be more happier, but really I am very pleased about how things went today—this is a very fun bike.


First up was loading up the bike, gear, getting some gas, etc. I got a bit of a late start due to wanting to watch the MotoGP qualifiers (spoiler proofing as it were) before engaging in other activities. Still even with the late start I ended up with plenty of time to enjoy riding around.


When I got out to the parking lot I was in for a bit of a shock. Where we use to ride was now full of short containers! This meant I would have to look around. Thankfully there are a good number of lots in the area.


First I checked the Marina lot, but it was full of homeless folks living out of their cars, and motorhomes. This is very much a part of California these days as people are getting priced right out of their homes. It is a totally horrible situation.

So I continued to drive around, and found a nice little area near some air conditioning equipment. Which is great because it makes enough noise to help mask the sound of the bike’s two stroke engine.


With the area selected I unloaded the bike, and then rode it around a little bit in order to find a place where the cones would be best placed. I found a decent enough location, and then suited up. I started out doing the cone riding with figure 8s. The eights are a lot harder than they look when a skilled rider is executing them. I was floundering. I will probably need to regress to circles. After a bit of the cones I decided to ride around the lot to see what the bike could do. In these photos you can see some of the tire tracks from the slicks.

The pavement was totally awesome. Very fresh, but with some debris. I brought my house broom, but it was no match for this surface. I am going to have to invest in a proper push broom.


I did bring some video gear, but had issues. Some video was recorded, but I’ll have to go back for more action to edit anything together. Thus I had to settle for some still shots—which are below. The bike ran fairly well. There are some hesitation spots in the early throttle that I’ll have to attend. The brakes are really horrible. I will have to figure out something before I can take the bike on an actual track.

There is a fair amount of spooge coming out of the tail pipe. The gas was mixed at 32:1, and this carb is much smaller than what was on the bike. It is likely that the silencer will need a repack.

Handling wise the bike was pretty nice to ride. I did nearly lose it once in the back corner. This was probably due to some rocks and sand. Again, illustrating the need for a proper broom. The engine produced very nice power. This is going to be an extremely fun bike once sorted, and even still today it was a blast to ride.