Author Topic: '73 500 - Subframe Fabrication  (Read 37632 times)

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Offline calj737

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'73 500 - Subframe Fabrication
« on: December 27, 2013, 03:33:27 pm »
So, like many others, addicted to turning one man's trash into a treasure. Case in point, a "free" (we all know how expensive these bikes become) and clear titled '73 500. Engine seized from sitting in the woods since '87 with velocity stacks and no cover. Mr Rusty came to visit about a decade ago, and apparently built himself a home.

Plan for the bike is:

- GSXR front end
- Spoked front and rear
- a set of CR26's
- MRieck head work
- New cam
- Overbore
- Monoshock rear
- MotoGadget M-Unit and M-Button (I hate wiring) and M-Key (keyless ignition)

Haven't decided yet on the tank and seat combo, but should be something sporty and slight. More of a Street Fighter posture. Bike is for my 20 year old, so ergonomics are more forgiving when you are that flexible.

Disassembly began this AM.
http://s1290.photobucket.com/user/calj737/library/
« Last Edit: August 19, 2015, 06:58:32 pm by calj737 »
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Offline calj737

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Re: '73 CB500 From Worthless to...
« Reply #1 on: December 27, 2013, 03:40:18 pm »
If you walk through the Photobucket library, you can see the task ahead. There's not a great deal remaining from the original bike thats usable, hence the major modifications planned.

Odd thing is, despite the pistons being seized, the lower end (removed the oil pan) is clean as a whistle. Upon close inspection around the base of the head, jugs and fins, theres no evidence of it ever leaking oil. Hoping that I can get the covers off, the head off, and then the jugs. May get lucky with usable sleeves to re-hone or re-bore for a 536 or 572. Else, its new jugs or a new 550 motor as a platform for upgraded performance.

The picture with all the electronics and wiring is the "salvaged" parts that are heading off to forum members. some bits are still available, if you see something you need or want, let me know.

The other pile has some members "to be shipped" stuff, plus the remnants of usable items.

Funny, these bikes brake down into very small piles after a day with PB Blaster, an impact driver, and some propane.
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Offline riverfever

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Re: '73 CB500 From Worthless to...
« Reply #2 on: December 27, 2013, 03:54:34 pm »
I'll be watching this. I'm intrigued by the GSXR front end and mono shock.
http://forums.sohc4.net/index.php?topic=127186.0

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Offline rb550four

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Re: '73 CB500 From Worthless to...
« Reply #3 on: December 27, 2013, 09:16:47 pm »
I've been known to take a bike out of a scrap pile every now and again, thought I had rust, holy cow  that rear fender looks like it's own weight could fold it! Ha , and that spacer or what's left of it. Mr Rusty for sure, maybe Mr Rusty +.
At least the frame looks like it could be sturdy and every thing else is replaceable.
Looks like fun.
A few Honda 500's, a few Honda 550's, a few Honda 650's, '72 cb 450, a couple 500/550/650 hybrids, and 2001 750. 
  550 Snowbike -Somebody had to do it.
  And other upcoming cb projects.cb750a gl1100.....
Bikes past: 66 s-90, Yamaha enduro, '72 cl-350 Scrambler, Cooper  enduro, Kawasaki  enduro, 550 snowbike.

Offline calj737

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Re: '73 CB500 From Worthless to...
« Reply #4 on: December 28, 2013, 04:36:13 am »
What is not in the pictures is the original exhaust pipes and spark plugs. I took those out about 6 months ago when we took delivery of the bike. The pipes were so badly rusted on the inside, then when we grabbed them to wrestle them off the studs, they cracked and folded into our hands. I then poured about 2 cups of rust from the inside of each pipe...

The plugs, well, THAT was something. The metal screw ring had dissolved at the bottom of the plug hole, above the threads. What a chore they were to remove. Ultimately, they came out without marring the threads.

I then drained the oil, filled the ports with PB Blaster, Marvel, ATF/Acetone combos on and off for about 4 months (refilling the crankcase with inexpensive oil) to try to unseize the motor. No dice... Won't kick, won't crank free, can't roll it in a higher gear as clutch cable doesn't exist. I'll just pull it down to get the piston loose.

But again, oddly enough the case and internals from the lower side look immaculate. I do know the PO is a motorcycle guy and does take good mechanical care of his bikes. This one just got pushed into the bush when he switched to Harleys.

Oh well, PB Blaster is cheap and sweat equity is abundant.
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Offline KB02

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Re: '73 CB500 From Worthless to...
« Reply #5 on: December 28, 2013, 05:07:59 am »
I had the same starting point on the engine with my CB. No matter what I poured into the jugs they would not move. I ended up having to punch the pistons out with a hammer and a drift punch.  Water had gotten into the jugs and rusted the hell out of the rings. The good part is that it sealed off the jugs me from the lower end, so the bottom end stayed in good shape.  The rust did not worm too far pinto the jugs, either, so I was able to bore them out and use them.

Feels good bringing "scrap" back to life, huh? ;)
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Offline calj737

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Re: '73 CB500 From Worthless to...
« Reply #6 on: December 28, 2013, 05:16:52 am »
I'll let you know after I can feel my hands again. Whacked the ever-loving dog piss outta my thumb while driving out the steering races. Fortunately, it was cold enough outside that I couldn't feel the pain initially, but now my thumb is as swollen as my big toe. Or, I've lost all sense of my body's orientation and I'm putting gloves on my feet.

Who knows?
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Offline calj737

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Re: '73 CB500 From Worthless to...
« Reply #7 on: January 02, 2014, 04:45:35 pm »
Some pics of the torn down engine and the frame after an initial blasting. Wanted to get a clear picture of the frame's status and any repairs necessary.

Head came off quite easily, and now have the cylinders soaking directly with PB. Will rotate the soak with Marvel and ATF/Acetone to see if they'll free up. Still have some covers to remove. The kick starter joint is frozen on the shaft, and still need to remove the sprocket cover.

Found some more cancer on the underside of passenger foot peg brackets, but that's no concern as they will be removed anyway.
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Offline calj737

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Re: '73 CB500 From Worthless to...
« Reply #8 on: January 02, 2014, 04:46:42 pm »
The cancer patient...
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Offline calj737

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Re: '73 CB500 From Worthless Rust-ridden beast to Sport bike
« Reply #9 on: January 10, 2014, 06:02:48 am »
So when pulling down the engine, discovered some unusual "grind" marks on the back of the clutch basket. Cant find any evidence of interference on the cover, no metal in oil pan... Odd. Wonder if any of you 500 experts have an idea or can determine if this is the correct basket for the engine (perhaps a PO had to clearance the basket to fit?) Or was this a field modification normal in the day on this bike?
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Offline calj737

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Re: '73 CB500 From Worthless Rust-ridden beast to Sport bike
« Reply #10 on: January 10, 2014, 06:03:36 am »
Cover and face view of basket
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Offline cheftuskey121

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Re: '73 CB500 ** Need an Expert's opinion
« Reply #11 on: January 10, 2014, 06:17:52 am »
along for the ride cal  8)

Offline calj737

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Re: '73 CB500 ** Need an Expert's opinion
« Reply #12 on: January 10, 2014, 06:34:53 am »
I'm very flattered. In fact, this engine is seized up worse than your 450. I'll be resorting to kerosene shortly.
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Offline cheftuskey121

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Re: '73 CB500 ** Need an Expert's opinion
« Reply #13 on: January 10, 2014, 06:59:25 am »
precisely why I am along for the ride ;)

Offline wowbagger

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Re: '73 CB500 ** Need an Expert's opinion
« Reply #14 on: January 10, 2014, 05:33:09 pm »
Subscribed.

Offline rb550four

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Re: '73 CB500 ** Need an Expert's opinion
« Reply #15 on: January 11, 2014, 07:30:34 am »
I've had a few engines that were really stuck  like yours. I used to hang them from the rafters out of the bike, didn't always work so now I hang the jug off the rafters in the bike allowing the weight of the bike to do the work.

 This one hung for a week then

  I have had some that wouldn't let go no matter what so I did find a way to get them loose without destroying anything, while it's all hanging, I used a piece of leather as a buffer on the piston  after removing the concoction , a large socket upside down on top of the leather over the piston, a wide chisel on an air chisel. A few blats on 1 and 4 moving the leather to each piston, then the same on 2 and 3,just to shock the rust and break the bond, and the lower end dropped off leaving the jugs suspended and  everything in good shape... well , that's how I do it if you needed some more ideas.
A few Honda 500's, a few Honda 550's, a few Honda 650's, '72 cb 450, a couple 500/550/650 hybrids, and 2001 750. 
  550 Snowbike -Somebody had to do it.
  And other upcoming cb projects.cb750a gl1100.....
Bikes past: 66 s-90, Yamaha enduro, '72 cl-350 Scrambler, Cooper  enduro, Kawasaki  enduro, 550 snowbike.

Offline calj737

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Re: '73 CB500 ** Need an Expert's opinion
« Reply #16 on: January 11, 2014, 12:39:42 pm »
Stress and impact are the next step. I've been cooking the cylinders much of the morning. The challenge has been that 1/4 are so near TDC, that the Clint won't hold much fluid, so it's dowse, light, dowse, dowse, dowse, etc... You get the idea. Like tending a wet fire.

BTW, I chatted this am with a friend who is a Japanese bike mechanic, a quality old timer, and he looked at the clutch and explained the filing marks are factory made. Apparently they are from cleaning up casting burrs. Good to know someone had not been tampering with this piece. I never noticed them on my recent 550 build, duh...

Anyway, a couple of pics from the rust BBQ. Fortunately, was also raining cats and zebras today (again). May trade these bikes for a center console if this weather persists.
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Offline calj737

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Re: '73 CB500 *** Engine freed***
« Reply #17 on: January 11, 2014, 04:23:16 pm »
So, after hours of adding fuel and braving the wind and rain, finally got the jugs free from the block.

http://s1290.photobucket.com/user/calj737/library/?sort=2&page=2
http://s1290.photobucket.com/user/calj737/library/?sort=2&page=3

Mid-way down page 2, you can see where the cylinders were still afire. Used some serious leverage on the rotor bolt while the fire burned to get the crank to budge. Rotation moved the cylinders up, and 1-4 pistons down. This identified 2-3 as the "stuck" pistons since they would not move any further up within the cylinders, yet 1-4 had already retracted below the sleeves.

More fire, some propane directly on the bottom of the sleeve, and more leverage on the crank. Once i could see the skirts from 2-3, I blew out the fire and carefully rotated the crank until the head was freed on the studs. Who says donuts aren't a good diet?

Examination reveals rust rings on 2-3 cylinders, but overall the engine still looks pretty good. Irrelevant since a full case teardown is coming to hot tank the case, powder coat and bearings/seals as necessary.

Chef - If you're following, I used Seafoam as the "accelerant" since I could not find any kerosene in my town (don't know why its not sold locally anymore). Also used a propane torch directly on the piston tops and then again at bottom of sleeves as I made progress. If I can get this engine apart, your 450 will come apart too. Rooting for you on your Dad's surprise!
« Last Edit: January 12, 2014, 04:35:14 am by calj737 »
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Offline riverfever

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Re: '73 CB500 *** Engine freed***
« Reply #18 on: January 11, 2014, 07:06:28 pm »
Wow. Nice job Cal.
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Offline bwaller

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Re: '73 CB500 *** Engine freed***
« Reply #19 on: January 11, 2014, 08:03:39 pm »
Those grinding marks on the basket is normal.

Offline calj737

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Re: '73 CB500 *** First bits back from Powder Coat***
« Reply #20 on: January 23, 2014, 01:07:16 pm »
So got some the hubs back from powder coat. Actually, its a ceramic coat for no other reason than it has the luster I am looking for (as close to clean aluminum).

That's Devin's (Cognito Moto) hub for the GSXR front end.
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Offline calj737

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Re: '73 CB500 *** First bits back from Powder Coat***
« Reply #21 on: January 23, 2014, 01:10:10 pm »
Some other pieces arrived today too: My MotoGadget M-Unit and M-Button. These will be wired in to alleviate the wire harness (simplified, left handed only control) and a single wire back to the M-Unit. Makes all the guess work of "what wire does what" for electrical retards like me. I like to think of it as "Garanimals wiring" for a nostalgic reference.

Pics show scale of size (wicked small) and ease of plugging into the M-Unit.
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Offline calj737

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Re: '73 CB500 *** First bits back from Powder Coat***
« Reply #22 on: January 23, 2014, 01:12:38 pm »
Also, sample pieces of the new bolts and nuts I'll be using on this project. I think they are very nice, and the threads are unbelievably smooth when spinning the nut on. Frankly, I got a bit of wood when assembling them.... Shhh! Don't tell the Mrs.
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Offline calj737

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Re: '73 CB500 *** First bits back from Powder Coat***
« Reply #23 on: January 23, 2014, 01:16:11 pm »
And lastly, sample color of powder coat for frame. Its a bronze. Had my guy do a test before the whole frame and swing arm to be sure I'd like it. Going to do the cases in satin black, and jugs in thermal dissipative (half way flat/satin black). So I think this bronze with the SS ARPs will look very clean and sexy.
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Offline SOHC4 Cafe Racer Fan

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Re: '73 CB500 *** First bits back from Powder Coat***
« Reply #24 on: January 23, 2014, 05:01:48 pm »
The ceramic PC for the hubs looks almost like plating -- very cool.  I like the bronze tone for the frame PC, too.
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