Topic: '71 CB500 Four Scrambler

[DurangoCB]

I accidentally deleted a draft of this introduction that had gotten way too long and detailed with my background in motorcycles and the like, which I am taking as a sign to keep it brief. 

I recently caught motofever, scoured Craigslist for weeks, then bought a 1978 CX500 off of a guy a few hours north of me.  Moto Nut at these forums, it turns out.  While there, I spied a 1971 CB500K in his shed, which he offered to deliver to Durango two days later for a good price. 



So two project bikes instead of just one.  Why the hell not? 



The CX500 is in great condition, so the plan has become to ride the CX while I restore- and tastefully modify- the CB500. 

[Stev-o]

Nice score.  What is the plan for the CB?   Something looks odd about the seat, is it a 750 seat?

[DurangoCB]

First order of business:  clear out the garage (small garage that already has 16 bicycles in it, which is our family obsession) and then build a work table on casters so I can scoot the project bike off to the side when I'm not working on it.  I mostly used scraps I had on hand.  Total cost:  $55.



Second order of business:  pull all the touring bits off.  Not my style.  (They're for sale, if you're interested.)



And then I started going over the bike to assess what all it needs mechanically.  Moto Nut was able to make it run when he first bought it and he felt confident that the bottom end is sound.  My plan is to get it running strong, then strip it down to the frame and go to paint. 



Things it needs:
Carburetors- rebuild
Tank- rust removal, cap gasket
Petcock- rebuild
Fuel Lines- replaced
Battery- replaced, + battery belt
Air Cleaner- replaced
Front Brake- piston locked, rebuild
Rear Brake- rebuild

[DurangoCB]

Nice score.  What is the plan for the CB?   Something looks odd about the seat, is it a 750 seat?

It could be- I'm new to SOHCs.  What I can tell you is that the metal wedge in the seat latch that locks into the notch in the post on the actual seat... that wedge is worn so the seat doesn't lock down.  So the seat tilts to the left side of the bike by 1" or more. 

But now that you mention it, where that seat meets the tank seems a touch ill-fitting.  I did notice that .

It's going to get a new seat anyway, though I don't want to give away too much and have people mad at me right out of the gates! 

[EDIT:  You're right- that's not the stock CB500 seat.  No wonder it seems awkward.  I'm surprised it fits as well as it does, though.  Thanks for pointing that out.]

[DurangoCB]

Tank (surface) Rust Removal

To cut to the chase, I now have a beautiful rust-free tank.  But first I spent 2 days doing it the Apple Cider Vinegar and BBs way and the results were unsatisfactory.  I ended up using Prep & Etch and I feel that's the way to go.  Easy, cheap, excellent results in 90 minutes total. 

I regret wasting two days waiting around for the vinegar to work.  But I love learning, so it was worth it. 



And I have a tip to share.  My gas cap gasket is brittle so the cap leaks pretty badly.  I've heard of others placing plastic bags under the cap, then shaking during the rust removal process.  I used a rectangular section of a bicycle innertube.  Perfect material for this use, plus it's significantly thicker than a plastic bag, so the seal is really secure and you don't have to worry about acid marring your paint. 

[Stev-o]

16 bicycles?! I'd clear some of those out so there not in the way!    Then more room for real bikes!

[Moto nut]

Wow you really getting with it, be sure to take lots of photos and bag and label everything no matter what, and keep everything in 1 or 2 designated boxes, have fun

[calj737]

Save yourself some headaches and simply buy a new, repro front Master Cylinder instead of rebuilding that piece. Seized brakes are often the result of a clogged return hole in the MC, plus corrosion of that piston. The caliper piston too corrodes, and it can be rebuilt. Pump out the caliper piston before disconnecting the caliper from the brake line. Then replace the brake piston with a phenolic unit, no rust anymore, lighter, and better resilience to heat while braking.

[DurangoCB]

Wow you really getting with it, be sure to take lots of photos and bag and label everything no matter what, and keep everything in 1 or 2 designated boxes, have fun

I'm on it!  Labeling, taking pre-disassembly photos, and most of all, having fun. 

[DurangoCB]

Save yourself some headaches and simply buy a new, repro front Master Cylinder instead of rebuilding that piece. Seized brakes are often the result of a clogged return hole in the MC, plus corrosion of that piston. The caliper piston too corrodes, and it can be rebuilt. Pump out the caliper piston before disconnecting the caliper from the brake line. Then replace the brake piston with a phenolic unit, no rust anymore, lighter, and better resilience to heat while braking.

I'll keep that in mind if the brake turns out to indeed be in bad shape.  As of now, I've barely glanced at it.  I just know that the piston will push out but won't retract.  Pushing the bike up onto the table took some effort. 

[DurangoCB]

So, what’s this?  It came off a couple weeks ago when I removed the passenger foot pegs and I was not paying attention to its orientation before loosening the bolt, which I’m sure violates Disassembly Rule No. 001.

[calj737]

Exhaust hangar bracket.

[DurangoCB]

That’s what I figured. This bike has an aftermarket exhaust that has its own hanger. PO must’ve just not wanted to remove the stock hanger. Thx

[calj737]

Bookmark this site and use for exploded diagrams and factory part numbers
https://www.cmsnl.com/honda-cb500k0-four-1971-usa_model459/partslist/

[Stev-o]

Black Sabbath Rules, Man!  Saw them recently on Classic Albums, good show.

[Scramps]

I used the same technique to seal up my gas tank while I let the evaporust do its thing.

Great minds and all that!

[DurangoCB]

Black Sabbath Rules, Man!  Saw them recently on Classic Albums, good show.

You know, I'm sort of a metalhead (but also into lots of other stuff) and I've always liked Sabbath, but in sort of a "greatest hits" kind of way.  Never really listened to a record start to finish.  Until a couple months ago... and holy sh*t, they really did cast the mold for hard rock/metal.  Those guys were 15-20 years ahead of their time and all heavy metal since then is based on what they did. 

ANYway... the weekends are for wrenching and I'm really, really enjoying this project.  And I appreciate this forum and the help you all provide.  I have several questions today- things I've tried to google and/or search here at SOHC but can't find the answers. 

Tomorrow I'm going to rebuild these 627B carbs.  At that point, I'll have everything I need to try starting this bike for the first time:
 
Tank de-rusted
New gel battery
Fresh throttle tube and cables
Fresh plugs

First question:
The oil is dirty dirty... should I change the oil before firing her up or is it okay to start the bike?  I'm going to tear it down to the frame and rebuild it, so I won't be riding it anytime soon. 

Second:
I had to buy new carb overflow line.  It's the standard clear pink stuff I've had on other bikes, but this bike had black overflow lines on it when I got it.  Is the pink stuff what I want? 

Third: 
These little fuel line clips that came stock sort of suck.  Surely they aren't doing much at this point, the weak little things.
 Are clips/clamps necessary on these bikes?  If so, what else is available besides these stock ones? 

And finally (for now):
The PO replaced the stock exhaust with these Harley style slash-cut pipes.  I don't mind the look so much, but they required the kickstand to be cut off (see pic).  I was given the original kickstand when I bought it, which the PO had bolted to the bike at the foot pegs. 

What would you do at this point if it were your bike?  Weld the kickstand back on the proper place and buy a new exhaust?  I'm not sure what I want to do.  Spending $400 on new exhaust sounds like a kick in the crotch- I'd prefer to avoid kicks to that region. 

[DurangoCB]

I just saw the pinned post in this forum.  I didn't realize tech questions shouldn't be posted here.  Sorry about that! 

[Stev-o]

I just saw the pinned post in this forum.  I didn't realize tech questions shouldn't be posted here.  Sorry about that! 

Not sure why you think that, your in the tech section where questions are to be asked. 

Answers:

1. I would change the oil.  I use Rotella (for diesel motors)
2. Pink fuel lines?   No!
3.  I use 3/16" fuel line, no clips needed. 
4.  I would look for a different exhaust unless I was building a drag bike!   Plus, I like having a side stand. 

PS.  I just picked up a '72 CB500.   I'll prolly restore it after I finish my current K5 project. 

[DurangoCB]

Not sure why you think that, your in the tech section where questions are to be asked.

http://forums.sohc4.net/index.php/topic,58514.0.html

Answers:

2. Pink fuel lines?   No!

Ha!  Got it.  What's the ID of the overflow lines?  Is that 3.5mm/ 1/8" ?

4.  I would look for a different exhaust unless I was building a drag bike!   Plus, I like having a side stand.

I definitely want a side stand.  Curious- what makes those pipes racing/drag pipes?  I have a lot to learn about exhaust and jetting still.

PS.  I just picked up a '72 CB500.   I'll prolly restore it after I finish my current K5 project.

Well, I'm going to need to see photos now. 

Thanks for your help, Stev-o!

[Stev-o]

Hey!

1.  This is your project thread, you can ask questions within it.
Project Shop area not meant to start a thread just to ask a question.

2. Yes.  https://www.ebay.com/itm/Grey-Fuel-Vent-Line-3-5mm-1-8-1-Meter-3-Feet-Honda-Kawasaki-Suzuki/172820955575?fits=Make%3AHonda%7CModel%3ACB500&hash=item283cee81b7:g:WQsAAOSwjg1ZkizJ

Save this seller for future needs, good prices and fast shipping out of CA.

4.  Really dont know, those style of pipes have just been called "drag pipes" for quite some time. Media hype?!

5.  Here's the CB500 I picked up last week for $50.  Came with a motor too, PO started engine rebuild but gave up. She is very ruff!!

[DurangoCB]

Just imagine the Before and After photos a couple years from now.

[DurangoCB]

Still haven't found time to rebuild these carbs and figure out how this old girls runs, but I've been doing lots of late-night reading and planning.  And today I dropped by the auto paint supply to ask about matching colors, buying a couple guns.  This is the bike that has me most inspired right now:  http://www.bikeexif.com/honda-cb550-street-scrambler  Both in style and that sweet blue/turquoise color. 

Then I drove across the street to ask the local welding supply joint about MIG welders, local classes, etc.  The feedback I've gotten universally from people, including my dad who races stock mods, is, "I could show you how to weld in 30 minutes... the trick isn't in the learning, it's in the practicing." 

Then I drove up a block to the powder coating shop, who happen to be the only powder joint in town, and they kinda had the attitude to match.  So that made my mind up about painting my frame DIY or paying someone to powder coat it. 

And last night I threw together a DIY home sandblaster and promptly shot sand into my eye testing it out. 

This CB project is getting a little more ambitious than I had intended- I don't know if I'll get started on the CX project until next winter.  But what's the hurry, anyway. 

[DurangoCB]

Sent from my iPhone using Tapatalk

[MauiK3]

As for painting a frame, I think you could start an opinion war over paint vs powder coat.
Powder coating is great on almost anything. The downside is that it's difficult to repair if its nicked.
As for paint, a lot of it is not very tough, but it is repairable.
I painted my frame with POR15 black with the POR chassis black top coat. Look on YouTube for Jay Lenos Garage and find the POR 15 episode.
It's really tough and it's repairable. I found it easy to work with. Use a respirator.  I had the frame media blasted in town here on Maui.