Neils 1978 CB550 F2 Project - Newbie Let Loose

[Neilw]

Hi All,

I've just retired and purchased a project CB550 F2, 32000 miles with a view to restoring it so it's not rusty, all works, and safe to ride in the summer.

Some history on the Bike: it was originally sold on eBay in December 2025 by someone selling project bikes for his brother-in-law, who had passed away. It was listed as a non-runner, but had run 4 years ago and had been stored since.

The new owner wanted a small project, didn't work on getting it roadworthy, doing some cosmetic work before quickly flipping it to me, making a few hundred quid in the process.

So my plan is to get it running first, make sure the engine is good and go from there. I'll probably strip it down, repair and clean it, replace/renew the serviceable parts, and repaint the frame.

Then enjoy some rides in the summer.

I've never done anything like this before, but I am happy to dive in and learn as I go.

I've stuck a new battery in it and run into my first problem: the start button is dead.

The solenoid is good, and the starter motor is too. I shorted the solenoid to see if it would turn the bike over, and it did.

I opened the switch on the handlebars because it was filthy, so I've cleaned it as best I can. However, the push switch for the start button spring is not good, so I don't think good contact was being made. I tried to disassemble it and have managed to break a contact already, and it's mighty fiddly that I doubt I can get the switch together without removing the loom bit. going to figure out how to do that now. What is my likely success rate of repairing this and getting it working again?

Are there serviceable parts available? I can't find a parts list, just for the whole unit.

Also, there is something up with my fuse box. It appears one of the fuses has a loop with another fuse on it. If I take it out and just use the fuse, there is no power. Could it be a fault in that particular fuse? When I reinstate it, power is restored.

Thanks for reading, I'll post as I go with pics, and I'm sure I'll have management questions.

[Bryanj]

Depends on which RH switch you have as to the chances of repair, the us type that the headlamp goes through is slim

[Neilw]

Depends on which RH switch you have as to the chances of repair, the us type that the headlamp goes through is slim

The cables pass through the handlebars and terminate at a junction box below the coils (not into the headlamp). As you can see from the photo, these are the two electrodes, one of which I broke. Am wondering whether i can repair if there are parts available.

[Johnny4428]

Your fuse box has had a by-pass op! 🤭 Probably because these old fuse box’s become fair. If you’re not bothered too much about what’s behind the side panel you could fit a spade type fuse box. Thinking about doing it on my 550.

[Bryanj]

If that white? Plastic piece is cracked/broken you need a new switch

[Oddjob]

I seem to recall there is a small pin on the back of the button, a small spring goes over this, which makes the button return. Can you feel this in operation, the spring normally rusts through after some years and the button tends to just flop around. The pin on the button goes through a small hole on an internal plate with the spring pushing against this plate for its resistance. As you press the button the pin goes further through and connects with the contact on the other wire, this activates the starter solenoid. However your switch is so dirty and full of crap I doubt this was happening. Unless the internal plates are broken or missing it should be a simple fix.

[Neilw]

I seem to recall there is a small pin on the back of the button, a small spring goes over this, which makes the button return. Can you feel this in operation, the spring normally rusts through after some years and the button tends to just flop around. The pin on the button goes through a small hole on an internal plate with the spring pushing against this plate for its resistance. As you press the button the pin goes further through and connects with the contact on the other wire, this activates the starter solenoid. However your switch is so dirty and full of crap I doubt this was happening. Unless the internal plates are broken or missing it should be a simple fix.

It's exactly as you've described. The spring appears to be broken, and I managed to break the connection to the white piece of plastic. Assuming I can solder the broken wire and replace the spring, I have no idea how to reassemble, as the spring needs to be fully compressed so  the other two parts can be slotted in for it all to work, and you can't get tools or fingers in there to do it.

[Bryanj]

You need the optionaly japanes spider with mechanical degree OR a lot of luck!

I have spent literaly hours trying to repair one and very, very ocasionaly only 10 mins.

The least frustrating way, but not the cheapest is a new switch

Just for a sxreenshot from CMSNL

[Bryanj]

Also this ebay one BUT the wire colours are different

Sorry forgot to attach, done now

[Oddjob]

I’m saying this without trying to promise anything. I’ve been extremely unwell recently and am still unable to do a lot of things I used to be able to do. I do tend to collect broken switchgear and have built up a supply of some of the internal parts, I may have just what you want or I may not. The problem is looking for them, that may be beyond me at present depending on where I decided to store them. Post some pics up of what you think is broken and I’ll see if I can help out.

I personally find fixing these switches easy, not sure why, perhaps I can good fingers (although not at present). If you’re unable to fix it I may be able to have a crack at it, I think I can manage little jobs like that.

Give the switch housing a good wash out with petrol or similar, see what we are facing, really grotty in there.

I’d say someone had bodged the harness up somewhat badly.

[Ken4004]

Hi Neil

Just seen this on eBay if you’re interested.

Regards Ken

[Ken4004]

You might find if the switch is not exactly the same the internal parts maybe

[Oddjob]

Avoid avoid avoid. No light switches in that switch.

[Bryanj]

Correct Ken, i didnt look close just googled the part number from cms, it was stupid o'clock in my defense, appologies to op

[Ken4004]

No Problem Bryanj

I just thought that even if the assembly was not exactly the same the internal  might be , big companies like Honda will also try and use existing designs instead of re inventing new parts every time to keep design and production costs down.

I did have slot of issues with my switches when I rebuilt my bike but managed to re fettle everything and now it’s working well.
These switches when exposed to the elements over long periods of time just disintegrate into a pile of rust, I actually totally retired my bike because every time I fixed one thing something else went wrong so I decided to rebuild the whole wiring loom.
During this adventure I found lots of corrosion throughout the loom with lots of wire nearly corroded through so well work doing, sorry waffling on too much.