Author Topic: 1975 CB550 K Rebuild & Minor Mods  (Read 17745 times)

Offline Bootsey

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1975 CB550 K Rebuild & Minor Mods
« on: Feb 11, 2014, 03:45:15 »

I've just gotten a hold of a project bike. 1975 CB550 K, 16000 miles on the clock, motor is locked/seized, the bike as a whole is in pretty rough shape, but I think it has plenty of potential. It's a project to keep me occupied whilst I go through recovering from some health issues, something I can work on when I'm well enough to do so. I'm not yet sure given my health, and experience, whether I've bitten off my than I can chew, but I figure whilst I can still bite, I'm gonna get to chomping. That said, I think it'll be a slow moving thread, so bear with me. It's my second bike, and before I got ill, I worked with CNC machinery, so I have OK mechanical skills.

I've spent some time reading up on the manuals, and other posts on here, so I have a bit of a game plan together for now.My plan is to restore it as much to stock as I can, given availability and price of parts. Hoping to focus most of my efforts on getting everything mechanical correct, rather than major atheistic changes. Plus I think these bikes look rad stock.

Today I started stripping a bit of it apart. Took out the spark plugs. The plug on cylinder 4 wouldn't budge, even after a soak with WD40 and oil. Hoping its just rust, and not cross threaded. I figure since I'm planning to pull the head off, I'll play it safe, and not force it for now. I sprayed a some WD40 down the other holes.
Cleaned some of the chrome parts with foil and water, most of the rust seems to be on the surface.

From what I can see under the gaiters, there isn't any rust on the stanchions, which is a win.

So here's some pictures. Any thoughts, info, advice etc would be greatly welcomed.

Before stripping it.

It has taken a fair slide down the road at some point, from the looks, it was never ridden after that. From what I can see the frame and forks look straight, the handle bars, brake pedal, head light, stator cover and exhaust took some damage.

Some wasps must have called the bike home for a while, this was under the tank. One of the wasps (deceased) went down with the ship, and is still in the side of the carb.

The tank is a fair mess, and needs taking back to bare metal and repainting. I'd really love to keep the original colour/paint scheme, but I'm not sure whether or not its going to be achievable. I've seen some threads about how to redo the metal flake plaint, but I think it's beyond my setup.
There's a decent ding in one side, that I can't pop out. So not sure if I'll just have to fill it yet or not. The inside is pretty rusty. I am planning to clean it out with vinegar, then flush with bicarb and water. It's rusty along the exterior bottom, under where the chrome trim was, there is some bubbling in the paint, but can't really tell if its caused by interior or exterior rust. Not sure if it might have any pinhole leaks. If I clean it back to bare metal for repainting, and fill it will fuel, will any pinhole leaks be noticeable? Then if there is any leaks, I'll reseal it.

Under side of the tank looks OK, just some light surface rust.

Side cover needs replacing

Personally I love the look of the 4 into 4 exhausts. Unfortunately the right upper pipe has a gaping crack in it, probably from the crash. So I'll have to try find a replacement, which in Australia might be quite expensive. Otherwise I'll have to rethink it.

I opened up the master cylinder, and its filled with what looks like sawdust...I'm not sure if brake fluid over time can deteriorate like this, or if its got water in it, or if its eaten away some seals or something. Anyone ever seen this?

That's it so far. If you have any thoughts or advice, please let me know. Cheers!
« Last Edit: Mar 08, 2014, 05:44:26 by Bootsey »

Offline interceptor

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Re: 1975 CB550 K Rebuild & Restoration
« Reply #1 on: Feb 11, 2014, 11:35:54 »
Wow.  Are there any usable parts on that thing?  I'll watch, but I'm thinking you may be better parting it out and buying something that runs and can actually be used.  Did you get a title?  Not trying to be a dick, but your going to have to replace so many things on that bike just to make it safe to ride and thats not even getting into the engine.
Opinions are like farts... they stink and no one wants to hear it except yourself.

Offline Bootsey

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Re: 1975 CB550 K Rebuild and Minor Mods
« Reply #2 on: Mar 08, 2014, 05:27:58 »
Bit of an update. Changed the title slightly for anyone who may concerned with such things, as I wont be doing a full restoration. I have decided on a few small mods, but nothing major.

Firstly RE:Inceptor. Thanks for stopping by. I can see your point, but I suppose to be clear, I bought the bike with every intention of a full rebuild, replacing wheel bearings, brakes, steering bearings, motor internals etc, and what ever else showed up on the way, within reason. Yes, its a fair mess, but the majority of the parts are fixable, given time, which I have no limit on.

So I started tearing the bike apart. Took of the fuel tank, and removed the petcock. I then filled it with vinegar, and let it sit for a couple of days. Then flushed it with with water and bicarb, then flushed it with methylated spirits. All the rust was gone, but there was still some varnished fuel. So I filled it with nuts and ball bearings, and some acetone, gave it a good shake, and am letting it soak for a few hours. Ill post some pics when its done.

Pulled apart the master cylinder. Took a fair bit of work and patience. Firstly the circlip ends snapped out, which was great....   >:( Got that sorted and started getting the piston moving, or so I thought. Instead it sheared in two. :o Eventually go the other half out, along with the springs and seals. The bore looks good, no scoring.
Also tidied up the master cylinder cap, and gave it a paint.

Stripped all the wiring, fenders, lights, gauges, etc. Cleaned some of the chrome as I went.Some of the chrome still has pitting, not sure if ill be able to get it all out. So might possibly work the chrome back until it looks like brushed.

Drained the oil. Ran a magnet through the pan, and then poured the oil through a cloth to see if the was any metal shavings, it was all clear. Removed the sump, and there was only a few small specks on the pickup.

Removed the airbox and battery box. Then I pulled the carbs.

Removed the front end. Forks look OK. There is the usual rust on the tubes under where the headlight ears were, but nothing in the area of travel. Rolled the stems across my workbench to check they didn't have any major bends, they look good, now need a good clean.

Removed the triple clamp and the stem head bearings races, the plan is to replace with tapered bearings.

Took off the rear wheel and brake linkages, then rolled the bike over onto its side, and unbolted the motor mounts, and lifted the frame off. I then knocked out the swingarm pin, it looks to be in great condition, there was no play in the swing arm. From what Iíve read, there is short bushes either end of the swing arm, I canít really tell by looking at the inside. I assume a blind bearing puller would be needed? They usually get changed over to bronze bushes?

Made up a basic engine stand and started tearing down the motor. Had to wait for a impact screwdriver to come in the post, because those screws weren't going anywhere without a some persuasion.

Removed the head covers. Then went about removing the head. Due to the engine being seized, getting the cam sprocket bolts undone was a bit of a pain, but after grinding down a spanner, it was all out.
The cam followers, and cam journals all look to be in great condition.

The cam has some pitting on the leading edges on most of the lobes, but from what I've read this isn't too big an issue? Anyone got any advice or experience? I think they look worse in the photos, they're quite shallow, I'd say the pits would be 0.2mm or so max.

Cam chain guide and tension. Do these look ok? Doesnít seem to be much wear from what I can see.

The spark plug on cylinder 4 was extremely tight. It did screw out, and surprisingly wasn't cross threaded, but it looks as though a couple of the threads are damaged. I'll trying running a tap down the thread, when I get one the right pitch. I donít think it will need a heli coil.

All the gasket surfaces look good, no noticeable dings. The pistons seemed to be stuck to the walls, so I poured a mixture of diesel, oil, and a dash of acetone on top, and let them sit for a couple of hours.

Got the jugs up off two of the pistons, but was still stuck on the other two, so left it to soak overnight. From what I can see of the cylinders, there are no marks, or scoring.  :D

Thats all for now, hopefully get the jugs off tomorrow, and see what the pistons and bottom end is like.
« Last Edit: Mar 08, 2014, 05:44:47 by Bootsey »

Offline interceptor

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Re: 1975 CB550 K Rebuild & Minor Mods
« Reply #3 on: Mar 08, 2014, 12:19:42 »
Looking good.  I`m excited how everything is turning out so far.  Good job!
Opinions are like farts... they stink and no one wants to hear it except yourself.

Offline Bootsey

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Re: 1975 CB550 K Rebuild & Minor Mods
« Reply #4 on: Mar 11, 2014, 23:18:17 »
So the pistons proved to be a little more stubborn than I initially anticipated, but I guess that was my first mistake, as expectation is the mother of all heartache.

So I'd left the pistons to soak with diesel and oil. Next morning tried to move the jugs, no dice. Grabbed a rubber mallet to give it a light tap to see if it would move. Tried this gently for a while, no luck, and instead I ended up chipping one of the fins. Grrrr >:(  I'll should be able to cold weld it later though.

Put the hammer down, and thought I'd try to work a little smarter. I had the jugs raised off the base a little, so I put a ratchet strap through under and around the jugs, then hooked it up to the rafters, to see if I could could get gravity and the weight of the motor to do the work. Still no luck. Decided that heat was going to be needed. Unfortunately no longer have the oxy-acetylene setup, so I had to improvise with a method I had seen on SOHC4.

Again I left the pistons to soak in some diesel and acetone. Did some reading and found acetone and ATF was a proved penetrant. Didn't have any ATF, and it was a public holiday. Did have acetone, 2 stroke oil and hydraulic oil. So I made a 50/50 mix of acetone and 2 stroke oil, as I read the rust inhibitors in 2 stroke oil can be helpful at breaking stuff free. Poured  some in each cylinder. Then I made a wick from some rag dipped in acetone, and lit it up.

I did this about four or five times, getting it to move a little each time after it cooled. I was able to get the outer two pistons free of the sleeves, and ascertain that the bottom end was OK, and the crank could turn. So I greased the cylinders, fitted the pistons back in, fitted the head, and then gently rocked the crank back and forth with a socket on the stator bolt, and eventually got it to come free.

I had started to wonder what condition the cylinders might be in, that given how frozen it was, there might be some serious rust pitting, but thankfully I was pleasantly surprised. :) There's one tiny bit of very light surface rust on the #3 cylinder, which was the problematic cylinder, but the rest looks like a hone should do.

The pistons need a good clean, the wristpin on #3 is a bit stiff, so next I'll take them off and clean them up, and see what shape they are in.

« Last Edit: Mar 11, 2014, 23:32:35 by Bootsey »

Offline Brodie

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  • Gold Coast, Queensland
Re: 1975 CB550 K Rebuild & Minor Mods
« Reply #5 on: Mar 11, 2014, 23:39:54 »
I am going to watch this, good to see someone else bringing back a "junk" bike.
I'm not sure, but don't ask Brodie.

Way to many build and half done projects to list here.
Sr250, Gs750, Z50A, XV1100, A10, Z160A.

Offline canyoncarver

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  • 'hacking is learning'
Re: 1975 CB550 K Rebuild & Minor Mods
« Reply #6 on: Mar 12, 2014, 15:25:07 »
This should be interesting.  I'm in.

Offline Bootsey

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Re: 1975 CB550 K Rebuild & Minor Mods
« Reply #7 on: Mar 20, 2014, 03:23:22 »
Nothing too exciting to report, started back on treatment, and am feeling pretty average, so I have just been working through some small bits and pieces. Also I discovered the Ichiban Moto thread, so that has chewed up a few hours.....

Ordered some parts, so waiting on them to arrive.

Another ghetto hub retainer tool and valve spring compressor were born. Got the retainer out fairly easily, thankfully. Threads seem all good.

Weather has been good, so I thought I'd get some painting done before winter sets in.

Soaked the foot pegs mounts in vinegar overnight, was surprised how clean they came out. Then just hit them with a wire brush. I've cleaned up and primed the centre stand, side stand and footpegs mounts so far.

Cleaned 90% of the frame with a wire knot wheel on the angle grinder, then tried out the  DIY sand blaster for the unreachable parts. It's slow going with the compressor I've got, but it works OK.

Offline madmatt1

  • Posts: 350
Re: 1975 CB550 K Rebuild & Minor Mods
« Reply #8 on: Mar 20, 2014, 03:33:20 »
On your swingarm-
When you pop those dust caps off the ends of it, you should be able to knock them out by hand with a drift and a hammer. But it will be easier to see in there when you take those caps off. They are probably cemented on there with old petrified grease, but they just sit on the swingarm. And yes, upgrading the bushings to bronze bushings or needle bearings is a great idea!
CL350 build thread:

1977 Kawasaki KZ1000
2003 Suzuki SV1000N
1975 Kawasaki KZ400
1977 Honda CB750K basket case

Offline Aircoolin

  • Posts: 259
  • 21 years young, 1972 Honda CB350.
Re: 1975 CB550 K Rebuild & Minor Mods
« Reply #9 on: Mar 24, 2014, 20:08:17 »
Awesome! I love to see people restore things that most would say isn't worth it. Keep up the good work!

22 years young.
1972 Honda CB350 - In progress.
1969 VW Bug - Slammed daily.
1971 VW Bus - Sold
2004 Yamaha R6