Topic: '71 CB500 Four Scrambler

[DurangoCB]

If I had the cash, I’d be all over it.

[Scramps]

I love those buttons, looking forward to seeing how they’re implemented


Sent from my iPhone using Tapatalk

[flyinelvis]

Hi Durango, loved your area while on a mountain biking adventure a few years back.  Beautiful, absolutely beautiful.  I’m a l-o-n-g time lurker here at SOHC4, this may very well be my first post (can’t recall).  Anyway, looking to get back into the 550/4 one day soon, although they’re pretty difficult to find here in the southeast.  Went looking for one a few years back and ended up building 3 CX500’s, before moving on the the GT647 Hawks.  Now it’s time to circle back.  OK, enuff about me...

You may scan eBay for a used CBR600RR (or other later vintage bike) throttle as they are very similar to the previously posted throttle and may be less expensive and of a bit better quality.  I’m putting one on a Hawk once I settle on cable length with Motion Pro.

Very much enjoying your build thread.

Carry on...

[DurangoCB]

That's good to know- thanks.  Life is getting in the way of progress on this bike, so it may be a month or two before I settle on a throttle.

We love it in Durango.  The mountain biking is what brought us here.  Previously lived in Prescott, AZ for 12 years and moved here 5-6 years ago.  I managed bike shops for years (don't anymore) and my wife runs a mountain bike coaching business. Bicycles are our religion, so we moved to the most beautiful temple we could find!

[Stev-o]

We love it in Durango.  The mountain biking is what brought us here.  Previously lived in Prescott, AZ for 12 years and moved here 5-6 years ago.  I managed bike shops for years (don't anymore) and my wife runs a mountain bike coaching business. Bicycles are our religion, so we moved to the most beautiful temple we could find!

Have you biked at Durango Mt Resort?  We were there a couple years back, the weather was light rain and they would let us go up with bikes.  So disappointing...

[DurangoCB]

We love it in Durango.  The mountain biking is what brought us here.  Previously lived in Prescott, AZ for 12 years and moved here 5-6 years ago.  I managed bike shops for years (don't anymore) and my wife runs a mountain bike coaching business. Bicycles are our religion, so we moved to the most beautiful temple we could find!

Have you biked at Durango Mt Resort?  We were there a couple years back, the weather was light rain and they would let us go up with bikes.  So disappointing...

Yes!  And you should come back and try again.  Three years ago a local guy bought DMR back off of the parent company (you know, the type of company that also owns Enterprise car rental and Colgate toothpaste LOL), changed the name back to Purgatory and have been really turning it back around.  AND, they've put in a lift-served bike park, gravity roller coaster, zipline, etc.  I'm a cheap bastard but I actually purchased a summer pass last year because the riding is so much fun. 

If you come back, give me a shout. 

[Stev-o]

We love it in Durango.  The mountain biking is what brought us here.  Previously lived in Prescott, AZ for 12 years and moved here 5-6 years ago.  I managed bike shops for years (don't anymore) and my wife runs a mountain bike coaching business. Bicycles are our religion, so we moved to the most beautiful temple we could find!

Have you biked at Durango Mt Resort?  We were there a couple years back, the weather was light rain and they would let us go up with bikes.  So disappointing...

Yes!  And you should come back and try again.  Three years ago a local guy bought DMR back off of the parent company (you know, the type of company that also owns Enterprise car rental and Colgate toothpaste LOL), changed the name back to Purgatory and have been really turning it back around.  AND, they've put in a lift-served bike park, gravity roller coaster, zipline, etc.  I'm a cheap bastard but I actually purchased a summer pass last year because the riding is so much fun. 

If you come back, give me a shout. 

Good info, thx.  I have a trip planned to CO in August but we'll be about 300 miles away in Beaver Creek...

[DurangoCB]

Beaver Creek ain’t bad, either.

ColoRADo

[Pin2Hot]

It wasn't until just now did I make the connection between your username and the actual city in Colorado....

A buddy of mine and I passed through and stayed at a campsite on the north end of town, currently called United Campgrounds of Durango.  He and I rode our bikes from St. Louis to LA via Colorado / Vegas then headed north to Laguna Seca for the MotoGP race in 08.

http://www.pbase.com/pin2hot/gporbustday3
http://www.pbase.com/pin2hot/gporbustday4

Those were the two days we passed through your area.  Absolutely gorgeous out there, would go back in a heartbeat.  We got to see the Silverton / Durango Narrow Gauge train pass by our campsite before we left which was really neat.

[DurangoCB]

That sounds like a great adventure!  I know the campground well.  When we lived in Prescott, AZ we used to come up to Durango a few times a year and always stayed at the United Campground.  Especially to people who had spent a dozen years in Arizona, the grass at United was oh so soft and luxurious.  And the train is cool, too.  One of the great things about living here is hearing that old whistle blow a few times every morning and every night. 

[DurangoCB]

Almost forgot I was in the middle of a CB500 project until yesterday. 

Where I am now, with the bike in pieces in boxes, feels like the crux of the project.  Where lesser men eddy out and two years later the bike is on Craigslist. Not me, no sir. Getting over that hump!  If I can just get the frame and other parts to the powder coater, it will be more or less downhill from there.  So I took yesterday to make some ugly welds and fabricated brackets to allow me to get the Made in China seat on and off easily.  The welds are uglier than sin but everything worked out pretty well.  And I determined that I actually have room for another shallow tray in the rear section of the subframe, where I can park some electrical, including the Rick's R/R. 

And my plan to mount the Revival LED turn signals at the rear of the frame is going to work.  Flat plate across the opening where the subframe was chopped with a nut welded to the backside which the LED housing will screw into.  Wiring will be internal for just a few inches. 

That's the last step before shaping and sanding the rough spots, then to blast and powder. 

[Scramps]

I love it, can’t wait to see how it turns out

[Gurp]

Great work so far cant wait to see more progress!

[DurangoCB]

Thanks, fellas.  Lots of learning along the way, which is kind of the point.  Otherwise, I'd be making an easy monthly payment on a new bike. 

I've had some good luck with things that seem notoriously difficult for SOHC owners but that I found to be fairly straightforward.  One was mounting new tires.  Set the wheels and tires out in the sun if you can.  Work on getting both beads into the deepest part of the rim channel before you grab your tire levers.  Piece of cake getting them off.  New rubber goes back on even easier.  It's just a heavier, more stubborn version of a bicycle tire. 

The other task was replacing the swingarm bushings.  I assumed I was in for a fight and immediately went for the hacksaw blade but at the end of the job I realized that I had managed to cut all the way through only one of the bushings but the other I didn't make it through.  Guess which bushing came out easier?  Yep, the intact one.  The slit allowed it to collapse a little, but it also ovalized just enough that it made it difficult to tap out.   

I used a 24" long piece of 1/4" flat steel.  Tap the bushing out from the opposite side.  I had to resharpen the corners of the flat steel a couple times along the way on the bench grinder to keep them square.  Tap at the 12 o'clock position on the bushing, then the 6 o'clock... back and forth until the bushing pops out.  As long as you're lucky like I was and your swingarm is in decent condition.

I have a homemade bearing press that I used to set the new bushings.  I tried one bushing in the freezer overnight and one at room temp.  Didn't seem to make any difference.  They both took the same amount of pressure to drive them in. 

I've also managed to find time to shave off the front brake switch mount and reshape the lower clamps. 

[DurangoCB]

Oh and keen eyes will notice that I need to find a skilled welder (so, ahem, definitely not me...) for a few small things, including the missing fork stop on that lower clamp.  The PO had someone replace it with a bolt that they made the same shape as the original stop, but I'd prefer someone fab something nicer.

[Scramps]

I love it when a plan comes together.

So the swing arm bushings, everyone seems to want to replace the original style with brass. What are the advantages of brass over the original ones?

I ask because I’ve already reassembled mine and it seems to be fine, but now I’m starting to think I may have made a mistake

[DurangoCB]

I love it when a plan comes together.

So the swing arm bushings, everyone seems to want to replace the original style with brass. What are the advantages of brass over the original ones?

I ask because I’ve already reassembled mine and it seems to be fine, but now I’m starting to think I may have made a mistake

I've heard two rationale:

First, galling is something that happens when certain materials are subjected to friction between them and it can often be worst when two pieces of the same/similar materials are rubbing against one another.  So if you want to make Part A out of X material, then the Y material that you make Part B out of should be selected such that it minimizes galling. 

The other reason is that brass is softer than steel and a bushing is actually designed to/expected to wear, so your permanent surfaces/parts (the ones you don't want to have to replace) are made of a hard material and the bushing, which is easy and inexpensive to replace, is made of the softer material. 

[DurangoCB]

Now that I re-read your question, I think what you're wondering is why does everyone replace the bushing at all. 

It's just another of the three dozen things that you go, "Hey, while I have this thing apart I might as well..." 

Again, bushings are designed to wear, albeit as slowly as possible.  But on an old bike like ours with some mileage on them, it's a safe bet that the bushings are worn to some degree.  For $40 and 60 minutes of work, might as well start your new build fresh in as many respects as possible. 

[Scramps]

This is valuable information, thank you very much

[DurangoCB]

Ahhhh... summertime.  Hope everyone is enjoying it so far. 

I figured that the damaged left-side stop tab on the lower triple clamps (my fix in the first photo) probably meant I would find some body filler in the right-side of the tank.  And sure enough. 

Any advice for removing the old Bondo and repairing the dent from bare metal?  Tools and materials that are ideal? 

[calj737]

Grind out the filler with an air-driven angle grinder and a red scotchbrite pad. Then assess the dent. Probably best to see a PDR (Paintless Dent Removal) specialist to straighten the tank.

[DurangoCB]

Grind out the filler with an air-driven angle grinder and a red scotchbrite pad. Then assess the dent. Probably best to see a PDR (Paintless Dent Removal) specialist to straighten the tank.

Thanks and done.  Your thoughts? 

[calj737]

Worst place possible, but the dent is not bad at all. A good PDR guy can fix that.

 He'll use a rod inserted thru the filler neck and push that dent out from the inside. Then possibly need to un-tweak the filler neck. I've done dozens of these tanks and only a few of them did I need to drill an access hole into the bottom to get at the dent. I then just patched it, welded it, and ground it down. Never could tell a repair was made.

[DurangoCB]

Thanks again, cal.  It's pretty impressive what you guys can do to straighten out tanks.  I reached out to a local PDR guy who said he would "give it a shot" and it would be $150.  I need someone with more confidence than that.  That sounded like a potential rabbit hole of both time and money. 

I was able to make my own tool with a 1/2" mild steel rod and got the dent to pop out about halfway, then used body filler to get where I needed it to be. 

[DurangoCB]

d1rtypelican, regarding our conversation via PMs, here are some photos of the subframe modifications for mounting the seat. 

(disclaimer: Calj called me on the quality of my welds, so be sure your welding skills are better than mine.)

If your bike indeed came with the same seat (eBay is flooded with them, so I believe it), it comes with a host of rubber bumpers, 4 bolts toward the rear, and two bolts at the front that hold a bracket they also include. 

I used the same principle for the bracket at the front but fabricated a new one that fit the bike better (pics when I get home from Moab).  I lost the rubber bumpers completely because they weren't even close to being a good fit for the CB500/550 frame.  And in the rear, I am using two of the four bolts and they fasten to the bracket I added.  Note that the bracket is arched, not flat. 

This seat is short, so be sure that's the look you're going for!