Thanks, SOHC4 Cafe Racer Fan, for posting the photos of my '75 CB550K. Here's a bit about me and the saga of this project. Apologies for the long post.
I've been riding motorcycles since I bought a new YZ80 in 1978. I've had dozens of bikes over the years, some of which I bought damaged after accidents ('82 750 Nighthawk) or in boxes ('77 GT750). I like mechanical things (heck, I'm a mechanical engineer) and have rebuilt more old vehicles and machines than I can remember. I did this out of necessity when I was young, and as a hobby now that I'm north of 50. Pictured below are a couple of my past projects and one for the future.
I had never done a frame-off motorcycle restoration and I've always loved the 70's CB/Fours. I have a well-equipped shop and was in need of a project, so I started looking for a worthy CB. It took 6 months to find this one (these photos from the kijiji ad):
I bought it in 2015 from a guy who was planning to fix it up but had too many projects. He had bought it from the original owner, who stopped using it in 1981 and stored it for 34 years in a spare bedroom of his house. It had ~15,700 miles, its MVI sticker expired in June of 1976 and it was last licensed in 1981. The original tool kit and owner's manual were included.
It came to me with a very clean 77/78 550K OEM exhaust system. The PO planned to use it because the original pipes were shot. It bolted on, but interfered with the rear brake lever, kick starter and side stand, so I sold it and bought a Delkevic 4-into-1 system.
The general appearance of the bike was decent for its age, but under the surface were all the signs of a 34-year sleep. The carbs were a mess. The front brake and clutch were stuck, although the engine rolled over on the kickstarter. O-rings and seals were hard, electrical connections were corroded and there was plenty of rust, especially inside the fuel tank.
My first chore was to get it running and rolling to see if it was a worthy backbone for a project. I changed the oil/filter, got the carbs into passable condition, unstuck the clutch/brake, adjusted the points and fixed a variety of electrical issues. I geared up a temporary gas supply and it started quite easily. The video below shows it was smoking, but I figured rings were stuck and there's no smoke now.
I drove it a couple of miles and ran it through the gears - all was good. I did a compression test on the warm engine, then posted the numbers here for opinions and apparently they're acceptable at 128-132 psi. Aside from the valve cover and rockers, I didn't touch the engine internals. It ran well, had fairly low miles, no leaks, good compression, and the camshaft looked fine, so I figured it was better left alone.
Thanks to other priorities, I didn't do much on this project from October 2015 to September 2017. I did most of the work between last September and June. Here's what I repaired/replaced:
Repairs- Overhauled carb and rack assembly
- De-rusted gas tank
- Rebuilt master cylinder
- Unstuck and cleaned clutch
- Disassembled, de-rusted and polished wheels (rear rim is a new one that came with the
bike) - De-rusted and undercoated fenders
- De-rusted taillight, fork ears, turn signals, rear shocks, grab bar and other chrome pieces
- Replaced seals and o-rings
- Replaced valve cover and rockers. As everyone here knows, the older 550 valve covers had a design flaw that caused excessive wear in the rocker shaft bores.
- Cleaned and repaired wiring harnesses
- Sanded, primed, painted and clear coated 100+ parts, brackets, bolts, etc.
- Sanded/polished engine covers, fork cases and ~20 other aluminum parts
- Disassembled, primed and painted seat pan
- Disassembled handlebar controls and painted housings
- Removed, cleaned, sanded and painted the engine
- Cleaned, sanded, primed and painted the frame
- Touched up paint on emblems
New Parts- OEM carb rebuild kits and jets
- Petcock rebuild kit
- Brake caliper kit
- Master cylinder rebuild kit
- Braided steel brake lines
- Brake shoes/pads
- Gaskets, o-rings and seals
- Gauge covers
- Spark plugs/caps
- Stainless steel engine and carb bolts
- LED instrument bulbs
- Ignition points
- Drive chain and sprockets
- Delkevic 4-into-1 exhaust
- Tires/tubes
- Air filter
- Ignition switch
- Battery
- Flasher relay
- Sealed beam headlight
- Fork cap bolts
- Warning decals
- OEM hand grips
Used Parts- Handlebars
- Valve cover
- Starter cover
- Mirrors
- Headlight bucket
- Horn
- Turn signal housings (2)
This project tested my determination more than any other to date. I was getting pretty frustrated towards the end - it seemed like there was another unexpected (often costly) challenge every day for a few weeks. It has reminded me that when a project is fighting me (and this one fought like a champ), it's best to take some time off and the problems will be much easier to solve when I come back with a fresh perspective. That's why it looked like this for about a week:
It's road legal now and I've put in about 100 miles shaking it down. I still have a few minor issues to solve, but this old bike is really working well. As the tach climbs above 6k, it pulls like hell and sounds divine. Below is a video of it running.
I believe the late 60's/70's CB series played no small part in building Honda's brand for innovation, performance and reliability. And to my eyes, they're as pretty as a motorcycle could be. I'm proud to have this sample of Soichiro-san's work.
During this project, I searched SOHC4.net hundreds of times. It is THE source for information on these bikes. You guys have never let me down - thanks! I hope to start another project thread here someday. I crave a 75-77 CB400F.
As for the nomination, it's an honor to be in such good company. Oette's Blue Falcon is a beauty - clearly the product of impressive skills and a great eye for design. Well done, Oette!
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