Author Topic: Time for a teardown! 1971 CB500K0 Restorarion (Read 5297 times)

daniel9441 · « **on:** June 05, 2016, 07:35:16 PM »

In January, I purchased a 1971 cb500 that had been wrecked by the previous owner. For $400 I got a dusty old bike minus a front end. I spent another $400 on a front end and an exhaust, along with a few other bits to get it running. After a nice day of riding, I decided it was time to tear the bike down for a frame off restoration. In a day, I bagged and tagged most of the bike. I hope to document the restoration process which will be completed in early July.

These photos are before I tore the bike apart. Below are some after photos.

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MickB · « **Reply #1 on:** June 05, 2016, 07:36:34 PM »

Great project Daniel, hope it goes well.

b52bombardier1 · « **Reply #2 on:** June 05, 2016, 07:50:16 PM »

I'm just getting started on my 72 CB500 so I will be following your progress very closely.

Rick

honder · « **Reply #3 on:** June 06, 2016, 01:24:00 PM »

I'm just getting into the rebuilding phase of a 72 cb500,.. I'll be keeping an eye out for your progress as well.

Bankerdanny · « **Reply #4 on:** June 06, 2016, 03:04:56 PM »

Cafe Racer Starter Kit, that's very funny.

daniel9441 · « **Reply #5 on:** June 06, 2016, 07:42:25 PM »

I got the engine off the frame today, and removed the front end from the bike.
To get the engine out, I unbolted it, laid the bike down onto a creeper, and pulled the frame back up -1 engine.
The 2 reasons I decided to begin the full restoration are shown below. 1 was a hole in the frame, which happened when a welded-on aftermarket locking mechanism made contact with the pavement during a PO's crash.

The second reason is this. A broken off bolt with the tip of an extractor in it. I broke off the bolt because I expected it to be reverse-threaded, and I broke off the extractor because I bought one made of chinesium. Such rookie mistakes

.

With the engine out of the frame, I could clean off it's many years of grime, oil, and what I think was algae. I think this engine is going to look great with some fresh paint.

I'll be taking the frame to a welder to have the hole patched, and a good used crank is on the way. Next up, I'll be cleaning off and inspecting many of the smaller bits of the bike.

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calj737 · « **Reply #6 on:** June 06, 2016, 08:30:23 PM »

That tubing is pretty dang thin.

When you swap cranks, you must accurately measure bearings to insure they're the correct fit (if yu didn't know this already). Plastigauge is your friend...

daniel9441 · « **Reply #7 on:** June 07, 2016, 05:40:38 AM »

Yeah I'm hoping it'll be a direct swap, but I'm going to plastigage everything to be sure

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daniel9441 · « **Reply #8 on:** June 14, 2016, 03:46:17 AM »

Just a couple updates. The frame has been dropped off at my welder's place. I will have it back by the end of this week. I also began the engine teardown. The pistons don't look too worn, just dirty. I will probably just replace the piston rings and give the cylinders a light hone.

daniel9441 · « **Reply #9 on:** July 03, 2016, 05:59:08 PM »

I've been painting and polishing recently. The frame has returned from the welder with the hole repaired, so it should be getting paint soon.
I rebuilt the forks

I installed the all-balls tapered bearing kit to replace the old loose ball bearing system. It felt good when I test fit it, and everything seemed to line up well.

Here is a look at the frame repair.

I have new gaskets and seals for the engine

Lovely shiny paint. I used rustoleum appliance epoxy and it looks great.

My goal is to have the bike back together and driving mid-July. I will pass on a new exhaust and a paint job for now so I can save up some money, but the engine will be back together this week and the frame paint should be all dry in 2 weeks. I have been painting and polishing smaller pieces as i went through everything, so it should come together hassle-free.

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Tews19 · « **Reply #10 on:** July 03, 2016, 06:21:25 PM »

The frame experts will chime in but merely filling the hOle may not be the correct way to repair. I think the structrual integrity is compromised.

daniel9441 · « **Reply #11 on:** July 04, 2016, 07:49:24 AM »

Quote from: Tews19 on July 03, 2016, 06:21:25 PM

The frame experts will chime in but merely filling the hOle may not be the correct way to repair. I think the structrual integrity is compromised.

My welder determined that since the frame is made of mild steel with no heat treatment, welding on a patch would be okay. I will inspect the patch closely for the first year of riding, but I'm not too concerned about it cracking.
I will remove stress from the frame in that area by heating it up with a torch. That should remove any tension caused by the weld.

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calj737 · « **Reply #12 on:** July 04, 2016, 08:24:07 AM »

Quote from: daniel9441 on July 04, 2016, 07:49:24 AM

I will remove stress from the frame in that area by heating it up with a torch. That should remove any tension caused by the weld.

Unnecessary and ill-advised. If welded, the frame is perfectly fine as is. The only thing to inspect for is rotted tubing in adjacent areas due to moisture infiltrating the tube via the prior hole.

Once something is welded, its fused solid again. If it is properly welded, its stronger than before. Work-hardened metal cracks beyond the repair and re-heating around that area only weakens the frame further. Leave it be.

daniel9441 · « **Reply #13 on:** July 04, 2016, 08:28:24 AM »

Quote from: calj737 on July 04, 2016, 08:24:07 AM

Quote from: daniel9441 on July 04, 2016, 07:49:24 AM
I will remove stress from the frame in that area by heating it up with a torch. That should remove any tension caused by the weld.
Unnecessary and ill-advised. If welded, the frame is perfectly fine as is. The only thing to inspect for is rotted tubing in adjacent areas due to moisture infiltrating the tube via the prior hole.

Once something is welded, its fused solid again. If it is properly welded, its stronger than before. Work-hardened metal cracks beyond the repair and re-heating around that area only weakens the frame further. Leave it be.

Alright I won't mess with it. The frame was solid, rust-free, and dry inside so I'm fairly confident in the strength of the surrounding tubing.
Thanks for your help

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Tews19 · « **Reply #14 on:** July 04, 2016, 08:31:31 AM »

Cal the man so what he said is gold. Looks like your frame is good to go!

Bootsey · « **Reply #15 on:** July 04, 2016, 03:01:40 PM »

Looks like a great project!
I couldn't tell from the pics, but did you pack the tapered steering bearings with grease? If not, maybe have a quick search on how to pack tapered roller bearings, it's a bit of a messy job.

daniel9441 · « **Reply #16 on:** July 04, 2016, 08:04:54 PM »

Quote from: Bootsey on July 04, 2016, 03:01:40 PM

Looks like a great project!
I couldn't tell from the pics, but did you pack the tapered steering bearings with grease? If not, maybe have a quick search on how to pack tapered roller bearings, it's a bit of a messy job.

Yeah I packed it with purple marvel grease, the camera just doesn't pick up in red colors very well.

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daniel9441 · « **Reply #17 on:** July 20, 2016, 05:11:42 AM »

Progress! Engine is apart, but will soon be ready for assembly. I plastiguaged the new crankshaft and all the tolerances were 0.015 to 0.02 inches. The rods have the same side to side play as the old ones, so I assume they are good. Pistons are being re-used with new rings and a cylinder hone.

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daniel9441 · « **Reply #18 on:** August 01, 2016, 11:01:31 PM »

More progress. Engine is in the frame, wiring harness is cleaned and mounted.

I also picked up a green and relatively dent-free tank to have repainted in candy starlight gold.

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calj737 · « **Reply #19 on:** August 02, 2016, 01:40:32 AM »

You might consider saving that stock green tank. If you are having paint done, have your dented gold tank repaired and painted. Stock survivor painted tanks are worth their weight to hard core restoration builds.

Just saying...

daniel9441 · « **Reply #20 on:** August 02, 2016, 10:32:43 AM »

Alright, I'm thinking of using the candy starlight gold paint from ct70paint.com (VMR paints?). Is their stuff any good.

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b52bombardier1 · « **Reply #21 on:** August 02, 2016, 11:20:11 AM »

People in the minibike crowd over on LILHONDA.Com have used their paint. I think it's expensive but overall not bad paint.

Rick

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calj737 · « **Reply #22 on:** August 02, 2016, 11:30:05 AM »

Quote from: daniel9441 on August 02, 2016, 10:32:43 AM

Alright, I'm thinking of using the candy starlight gold paint from ct70paint.com (VMR paints?). Is there stuff any good.

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many good reviews here too.

daniel9441 · « **Reply #23 on:** August 30, 2016, 05:36:16 PM »

As of last month, the bike is back together. I was having a horrible time bleeding my front brakes with the rebuilt caliper and master cylinder, but a new master from 4 into seems to have fixed the issue. Now I just need to adjust everything and take it out on the road for some tests. College is taking up lots of time right now, so hopefully the next time I'm home I will be able to take her for a spin.

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calj737 · « **Reply #24 on:** August 30, 2016, 05:43:58 PM »

Put some fresh tires on it first!

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Author Topic: Time for a teardown! 1971 CB500K0 Restorarion (Read 5297 times)