Topic: CB500 K1 Restoration

[Tumpe]

Greetings from Finland! I got encouragement to start project thread from another user here, so here goes.

I spotted the bike for sale on finnish classic bike forum at spring. At first I thought it's not what I'm looking for but after hearing the price and asking for few questions from PO I decided to buy it.  First picture is on purchase condition.

At first I thought this wouldn't be nut and bolt restoproject, but my OCD kicked in pretty quickly. I wanted to get original green paint scheme, and it would have look out of place with patina at bike elsewhere.

Frame was in good shape and mostly in original paint, it went to powdercoating after documenting the warning label positions etc. In Finland there have been some idiotic law in 70s,  that has forced sellers to weld covers to near steering lock on new bikes. I cleaned those off with grinder before taking  frame to paint shop.

 Bolts and springs etc. were also mostly original. After disassembly I send them to zinc-plating. I ordered the tank and side cover paints from cb-four.de, along with new instrument mounting rubbers and few other little things.

I sandblasted the tank to remove PO's black metallic paint. Noticed the bike had been originally gold doing that. I wanted to get Jet green scheme as mentioned earlier, because I think it's nicest of the original colors and goes better with chrome than gold. I sealed the tank with GPL-S epoxy paint and filled the couple of dings with filler. Right side cover was cracked and I ordered new from cb-four.de, left side was intact so it needed only quick sanding and primer. Then off to the paint shop they went.

I disassembled the gauges and painted the outer ring with satin black, faces were good with cleaning and wax on them. Wheels were also disassembled and aluminium parts cleaned of factory varnish and slightly polished. Rims I ordered from Cmsnl and David silver. ( Hint: DS is much cheaper option for front rim) I laced wheels with original newly plated spokes, have yet to order couple of rear spokes before truing.

Last picture is how the bike looks now,  got the tank and covers back from paint shop and they did a splendid job!
Have to acquire new tank badges somewhere, PO had changed them to wrong ones. Side cover emblems were in good shape, needed just dab of black paint to the edges. Next i need to rebuild front forks, already have them disassembled. New boots, top caps and seals and they're good to go. Original headlight holders are little crusty, but bearable on outside. Have to clean them in citric acid and check if they would be OK to fit back.

[HondaMan]

Wow, nice work!
I gotta follow this...

[newday777]

It is coming along nicely. The color on the tank and side covers looks great.

Is the trailer yours? The lid/cover is interesting that the bike fits under the lid. Do you have more pictures of the trailer?

[Tumpe]

Thank you both! Yes the trailer is mine. They are quite common here in Finland, I think its finnish-made and I don't know if they export these.


This is quite similar than mine: https://trailerman.fi/tuote/respo-750m301l150-42-jarruton-kuomukarry-750kg-150x300x42/

[newday777]

Thank you both! Yes the trailer is mine. They are quite common here in Finland, I think its finnish-made and I don't know if they export these.


This is quite similar than mine: https://trailerman.fi/tuote/respo-750m301l150-42-jarruton-kuomukarry-750kg-150x300x42/

I like it! Very versatile design too.

[Tumpe]

Little progress, made a DIY truing stand and got front wheel ready for tyre. Have been considering Metzeler Block C, any experiences on these?

Also rebuilt the forks with new seals, oil and reproduction caps from DS.

Plan is to build bike to rolling condition first and then start working with engine. It should be in OK shape, was running with no extra noises when I purchased the bike. PO have had this bike for 30 years, and he had rebuild the engine shortly after he bought it. Here is the list what have been done at this rebuild 30y and ~10k miles ago:

-New OS pistons and bore
-Primary chain
-Cam chain+slipper
-Bearing shells
-Bronze sleeves to rocker shafts and new shafts.

So I think engine should be in good shape internally, it's now done 65k miles. But I still want to open it so I can check, clean and paint it properly. Moreover, I ordered newer 550 valvecover from Ebay with locked rocker shafts, so I will swap it  while checking the cylinder head and valves. Also have to check rubber parts and tensioner etc.

But at first I have to order those few spokes to rear wheel, tyres, and also new collar and bushes to swingarm. Any tips to sourcing those swingarm parts? Or maybe good aftermarket options, collar was quite expensive at first look..

[denward17]

Nice progress and great looking bike!  Following for more updates.

Questions:
In post #1 at the top, the 3rd picture shows what appears to be something extra welded onto the neck frame, what was it used for?

Curious about how the bronze sleeves were made into the rocker shaft cover?  Can you take pictures when you get to it please?

[Tumpe]

Nice progress and great looking bike!  Following for more updates.

Questions:
In post #1 at the top, the 3rd picture shows what appears to be something extra welded onto the neck frame, what was it used for?

Curious about how the bronze sleeves were made into the rocker shaft cover?  Can you take pictures when you get to it please?

Thanks! For the first question: In Finland there have been some idiotic law in 70s,  that has forced sellers to weld covers to near steering lock on new bikes prior registration. Cover was supposed to make stealing the bike/cutting the steering lock harder.

I'll post about the sleeves when I get to the engine work, I'm curious about them too.

[HondaMan]

But at first I have to order those few spokes to rear wheel, tyres, and also new collar and bushes to swingarm. Any tips to sourcing those swingarm parts? Or maybe good aftermarket options, collar was quite expensive at first look..

Yes, the collar is expensive but is VITAL to the handling of the bike. The clearance between the inner bushings (after they are installed) and that collar must be less than 0.0010" (I rebuild them with bronze bushings, Oilite, to 0.0006"-0.0008") in order to make the bike handle well. You must remember that the clearance in the collar-bushing interface lets the rear wheel wiggle side-to-side by this distance:
[clearance X 2] * [18" (distance to rear axle)]
so even 0.0010" bearing clearance becomes 0.036" side-to-side movement back there at the axle. The rear wheel causes the bike to feel 'unfriendly' coming out of deep corners when it can move side-to-side by 1/16".

[Tumpe]

But at first I have to order those few spokes to rear wheel, tyres, and also new collar and bushes to swingarm. Any tips to sourcing those swingarm parts? Or maybe good aftermarket options, collar was quite expensive at first look..

Yes, the collar is expensive but is VITAL to the handling of the bike. The clearance between the inner bushings (after they are installed) and that collar must be less than 0.0010" (I rebuild them with bronze bushings, Oilite, to 0.0006"-0.0008") in order to make the bike handle well. You must remember that the clearance in the collar-bushing interface lets the rear wheel wiggle side-to-side by this distance:
[clearance X 2] * [18" (distance to rear axle)]
so even 0.0010" bearing clearance becomes 0.036" side-to-side movement back there at the axle. The rear wheel causes the bike to feel 'unfriendly' coming out of deep corners when it can move side-to-side by 1/16".

Understood, I will definitely replace the collar even though it wasn't terribly worn. What's your opinion on needle bearing conversion sets, Hondaman?

[HondaMan]

But at first I have to order those few spokes to rear wheel, tyres, and also new collar and bushes to swingarm. Any tips to sourcing those swingarm parts? Or maybe good aftermarket options, collar was quite expensive at first look..

Yes, the collar is expensive but is VITAL to the handling of the bike. The clearance between the inner bushings (after they are installed) and that collar must be less than 0.0010" (I rebuild them with bronze bushings, Oilite, to 0.0006"-0.0008") in order to make the bike handle well. You must remember that the clearance in the collar-bushing interface lets the rear wheel wiggle side-to-side by this distance:
[clearance X 2] * [18" (distance to rear axle)]
so even 0.0010" bearing clearance becomes 0.036" side-to-side movement back there at the axle. The rear wheel causes the bike to feel 'unfriendly' coming out of deep corners when it can move side-to-side by 1/16".

Understood, I will definitely replace the collar even though it wasn't terribly worn. What's your opinion on needle bearing conversion sets, Hondaman?

So far, I have not seen a single needle-bearing kit that has less clearance than the bronze-bushing set. I have [been requested to] removed several of those needle-bearing setups in rider's 750 arms that were sent to me after they had been installed and the riders found the swingarm to be loose and impossible to "tighten". I'm supposing that someone thought the later arrangements (they showed up on the CB750 DOHC bikes about their 3rd year, I think?) were somehow superior and adapted the tech, not understanding the need for the very tight clearances (as in, custom-fitted). It is the geometry that makes this issue so important in these early-style frames: with 18" long arms and 2 bushing sites at the front "corners" of the setup (i.e., at the pivot), the looseness multiplies by the time it reaches the rear axle. To solve this with roller-style (aka needle) bearings, at least one side (if not both) needs a tapered bearing(s) installation so as to set up a preload that controls the clearance problem. To date, no one has made one of these for any of the SOHC4 frames. There are some later frames that came with the types/sizes of tubes that let a tapered hole be bored into at least one side so the tapered-needle approach is possible, but in these bikes, unless one starts carving up the frame to install new pivot sites (as in, much thicker tubes were the bearings would reside), there isn't a way to do this without fully-custom-made, very thinly-tapered ( less than 10 degree angle) needle bearings. And then, the bearing races must be hard as nails in order to survive the road shocks: conventional needle bearings (as in, off-the-shelf versions) do not come in such hardened steels, nor shapes. So, it will have to be a full-custom product: it can't be made up [successfully] from out-of-catalog bearing parts as we know them now. I tried to do this with a major USA bearing maker (Bower) around 2005: in the end I would have had to pay more than $5,000 for the R&D and 'setup tooling' charges, and had to buy at least 1,000 copies of the resulting bearing with no guarantees of it working, at [then] around $125 USD per set. Ouch!

So, I went the route of using bronze, and use 841 bronze (aka Oilite) because it contains some oil in case the owner doesn't keep up the greasing schedule (because I guarantee them for Life afterward: they won't wear out for more than 80k miles, as shown on my own much-abused, often neglected 750). While I have done many arms for USA riders and some for Canadian brothers, I've only got one such rebuild running overseas, in Switzerland: he sent me his whole engine top end and the swingarm for rebuild!

[MauiK3]

Very interesting. I wonder why the Swiss fellow sent his parts all the way here, I would think there would be folks much closer to help him. Unless, of course, you are becoming famous! Which is good.

[HondaMan]

Very interesting. I wonder why the Swiss fellow sent his parts all the way here, I would think there would be folks much closer to help him. Unless, of course, you are becoming famous! Which is good.

I don't think I'm THAT famous (although he already had My CB750 Book, and was telling his biker friends to buy one, too)! I asked him [ahead of time] why he would send those parts this far, and found out that in Switzerland, you are not allowed to have someone 'rebuild' a motor vehicle (especially the engine), and getting one serviced there is both very expensive and time-consuming, requiring sometimes a 'permit' be issued to do the work(!). They don't have the usual automotive machine shops I'm used to having around, but have some precision machine places (mills, lathes, CNC machines, that sort of thing, maybe for watches?). You're apparently allowed to license a running old vehicle if it meets emissions, but not allowed to rebuild a non-running one, or something strange like that. I think he said it also had to be 100% "original", meaning: factory parts used for the rebuild, so I used Honda OEM pistons & rings and valves (2 were burned) - fortunately it was an early head with the Stellite valve guides, which were in fine shape, still, at over 80k Km on the dial. It was a bizarre explanation he sent, and I felt sorry for them. I imagine our Euro members have a better understanding of it?

[Sw1ssdude]

I can confirm that Switzerland has some really stern laws when it comes to motor vehicles. On the other hand, our DMV doesnt care about certain things: Indicators? run 'em or don't, see who cares... Jerry Can as a gas tank? meh... But you DARED to weld on the broken off passenger footpeg? WHAT?! Weld? on the frame?! Its load-bearing! Get it certified IMMEDIATELY (cost: around $1'000)

Its changing things that's a huge PITA: Different forks, new suspension, upgrade from drum to disc, different exhaust, or running dual discs in the front... things like that. rebuilding bikes yourself is no problem (albeit expensive: we are not part of the EU, so shipping costs triple-double... we dont have Amazon here... an o-ring for 50 cent sent over from Germany costs easily 17$ shipping...).

Car and bike culture are different here: most people go for 100% originality and showroom condition, as customizing is really difficult here... at least we are free to paint 'em as we like..

So i'd guess this swiss guy sent you these parts because of your reputation: he knew you'd do excellent work. (i might get back to you once i tear into my CB550..

[HondaMan]

I can confirm that Switzerland has some really stern laws when it comes to motor vehicles. On the other hand, our DMV doesnt care about certain things: Indicators? run 'em or don't, see who cares... Jerry Can as a gas tank? meh... But you DARED to weld on the broken off passenger footpeg? WHAT?! Weld? on the frame?! Its load-bearing! Get it certified IMMEDIATELY (cost: around $1'000)

Its changing things that's a huge PITA: Different forks, new suspension, upgrade from drum to disc, different exhaust, or running dual discs in the front... things like that. rebuilding bikes yourself is no problem (albeit expensive: we are not part of the EU, so shipping costs triple-double... we dont have Amazon here... an o-ring for 50 cent sent over from Germany costs easily 17$ shipping...).

Car and bike culture are different here: most people go for 100% originality and showroom condition, as customizing is really difficult here... at least we are free to paint 'em as we like..

So i'd guess this swiss guy sent you these parts because of your reputation: he knew you'd do excellent work. (i might get back to you once i tear into my CB550..

Wow! That would really cramp my style.
It's SO satisfying to rebuild an old Honda (sometimes a Kawi or two) that I'd fall out of my tree if I had to live there.