CB 450 twin. I said I needed a project

[cardinal]

Well, I found some leaks I think I am going to try to close them up using silver. If everything is clean, it should work great.

So in other news I am attempting to rebuild the front caliper, but the piston is not moving AT ALL. The reservoir is full, but I can't see any movement when I pump the lever. Is it possible to disassemble the caliper and pull the piston out? Or is using the pressure from the system the only way to remove a brake piston?

 

[pidjones]

You can remove the caliper, plug the banjo bolt hole with a plain bolt and o-ring, the replace the bleeder with a grease fitting and pump it out with a grease gun. No joke, this is how it's done and cleaning out the grease is no harder than dealing with the brake fluid. I got my metric gease fittings at NAPA.

 

[cardinal]

Went ahead and got a frame loop from Dime City. I opted for the extra Bend to try to keep the rear tire clearance where it should be. Was thinking I was going to braze it, but then decided to ask a buddy if he’d be able to come over and TIG it. Fortunately for me he said sure! Now I can figure out the rear lights and fender situation.

 

[cardinal]

I think the end may be near! I was waiting on the next steps for the bike because I really wanted a motogadget m-unit blue for this thing. I knew that meant that I'd be sinking a lot more cash in and wasn't ready to do it, so the bike sat for a while (also a few other pressing house projects took most of my weekend time). Then I got some good news at work and it came with a cash bonus! I decided that it was time to take on all the electrical. I got the m-unit, a new starter solenoid from Revival, a reg/rec from Rick's, turn signals, a tail light, bar switches, and a bunch of wires and shrink wrap. Now I'm almost ready to jump in. I'm working on a wire diagram that I'll post here. Feel free to chime in if you see anything that looks off. I'm not sure what I'm going to do for gauges yet, I'm really trying to keep the controls as clean as I can, but I'm thinking that I may just run the tach and LEDs for neutral, high beam and turn signal. Not sure.

 

[cardinal]

Ohh dang! This project is still alive! I moved along and got my LED headlight, taillight and turn signals wired up and plugged in the rest of the system to the m-unit. I improved the in-handlebar momentary switches and kind of got hung up on the dyna electronic ignition. I couldn’t find ANY examples of the dyna on a CB 450 and after posting in the electrical forum here, I eventually found a member that had completed this install in the same bike. It is not straight forward at all, but I finally got it in! After adjusting the timing and the cam chain and valve clearance, I decided to try to start it. It is turning and sounds like it wants to start, but I can’t get it to burn gas. I’m planning on digging into it tomorrow. Any tips from the collective wisdom on DTT? I feel so close!

 

[Maritime]

Make sure its getting fuel, spark and air all at the right time

 

[cardinal]

Make sure its getting fuel, spark and air all at the right time

I know the plugs are making spark and I can feel air from the carbs getting pulled in and the plugs are wet after an attempt to start, so there is fuel in there, I am still a bit confused about when the plugs should be firing. I set up my electronic ignition and it's working, but not sure the timing is what it is supposed to be

 

[cardinal]

I worked on the bike for a bit last night and decided to fix the front fender. I wanted something a little sportier and wanted to keep the connection between the forks so I don't lose rigidity. I pulled the fender apart, ground off the riveted on struts and hacked it down. I still need to clean up the edge, but like the result a lot.

 

[cardinal]

The final step was to drop the height a bit. I don't like seeing daylight between the fender and the tire.

 

[cardinal]

I needed to get the electrical system sorted, and decided to move the battery and m-unit up where I could access them easily, but I am keeping the stock air boxes, so there isn’t a lot of room to work with. I cut down the stock battery holder and bolted the reg/rec under it and the starter solenoid in the spot where the stock battery would have gone. I think it’s going to work out great.

 

[cardinal]

First start!

It finally decided to turn over and fire and I am so pumped! I never thought this day would come. It's been years and a lot of hours trying to make things work and now I have an engine that starts!!

On the negative side, I'm getting nothing on the left cylinder and I think my throttle cable is causing some problems, but I am counting today as a win. I'm going to guess that I'm still a month away from riding this thing. I need to get the brakes to work and I can't seem to get the motogadget to turn the bike off using the one button starter. The manual says that you double tap the starter and it will kill the bike, but that isn't happening for me. Anyone else seen this happen and have a solution? I've posted my wire diagram above if that helps.

 

[cardinal]

I am sorting out all the little things, so far the biggest problem I've had has been fuel delivery. I had the carbs cleaned, bought new floats and thought I had a bad float needle in one that kept leaking, so bought the OEM needle and seat. Installed it and it's still leaking! So with the bowl off, I filled it with gas and slowly, gas started coming out the overflow... I guess there could be a leak between the brass overflow tube and the bowl.

Anyone have experience fixing something like that? I guess I could smear POR over the seam, but ideally I'd just replace the bowl. Anyone have a spare?

 

[pidjones]

The brass overflow tubes develop splits. Fill the bowl with 91% isopropyl alcohol over the sink to check. I have successfully soldered up the cracks on a CB750F using a high powered butane iron and plumbing solder and flux. Or seek one on ebay. Epoxy and shrink tubing have been tried and failed.

 

[cardinal]

The brass overflow tubes develop splits. Fill the bowl with 91% isopropyl alcohol over the sink to check. I have successfully soldered up the cracks on a CB750F using a high powered butane iron and plumbing solder and flux. Or seek one on ebay. Epoxy and shrink tubing have been tried and failed.

Thanks for the response.
I was wondering if maybe it was the tube, but just thought there is nothing creating any stress on it, so figured if anything it must be the connection between the brass and aluminum. I'm curious about the epoxy route, do you remember what was tried and failed? I had a tiny hole in my gas tank that has sealed up with POR, maybe it isn't as effective on brass? I have experience silver brazing and may be able to fix it that way...

 

[pidjones]

JBWeld gas-proof, 5 minute, and household epoxys have been tried. My un tested theory is tat moisture somehow gets pulled up the tube and freezes. Or it was poorly made. Look closely and you will see the crack running up the tube. Clean it with a sharp point and try the solder (silver braze too hot for the bowl). I used plumbing solder and Ruby paste flux. By using a powerful iron, I was able to control the heat.

 

[cardinal]

I found a cheap replacement on ebay, but thought while I'm waiting for that to arrive, I'll try to seal the one I have with the POR tank sealant. It takes 4 days to dry, so I might get to try it this weekend to see if I stopped the leak.

 

[cardinal]

Replacement bowl came in and the overflow didn't leak, but I could not get a good seal on the face of the bowl. After playing in gas for a while, I decided to try the one in the pic above and it's working fine (for now) I'll report back if leaks develop.

In other news I somehow lost the clutch adjuster (number 11 and 16 in the image below). Maybe another victim of a bike in too many pieces over too much time. I can't seem to find a source for a replacement. Any ideas?

 

[cardinal]

I bit the bullet and ordered the part from cmsnl. And now I have a clutch! Another step closer. As I'm assembling the rear drum brake I've noticed that the engagement rod seems like it is too long. Does anyone here have a measurement for the stock rod length? Looking at the side of my bike the threaded end starts beyond where the arm would drop down at a 90. I'm not sure I'll be able to set this up properly. If I compare to what I see on other bikes, mine is definitely longer. Again, since this bike was non-running when I got it, I may have acquired the wrong brake rod. Maybe I can shorten it? Attaching a pic that I grabbed from YouTube and mine (the one without the arm attached)

 

[cardinal]

I got the linkage sorted. I did need to shorten the rod a bit. Used a tube as a sleeve to brass braze it back together. Now I'm having an issue with my front brake. I bought a new caliper and have a new caliper piston and seal, the piston does not want to slide very easily in the caliper. I had to use a vise to compress it in there an after bleeding the brakes it sticks and the brake rubs. The piston and the seal came with the bike, but were new (along with new brake pads). I bought the new caliper because the old one was a mess. I'm not sure if buying a new seal will fix this problem. Any thoughts?

 

[pidjones]

Are you certain the MC is releasing pressure? There is a tiny hole in it that releases pressure and often gets plugged. A small electric guitar string will clean it. Had to help a friend clear his last nignt.