My Honda CB100N project - “Rusty”

[GojuRyu5]

Hi all, I’m a newbie to the forum and to bike renovations, but thought I’d share my project and updates as I go. Any tips along the way would be useful.

 

So, this model was my first bike back in the mid 80s and when I saw a restoration project on eBay for next to nothing, I thought it was time I tried to get involved. Admittedly, I’d had a couple of beers and the fact that the project bike had no engine didn’t seem to matter at the time… I bought ‘Rusty’ for £127 and started a complete strip down; by individual nut, bolt, clip, bracket and wire.  The most I had ever done back in the day was change the fork seals (no mean feat in itself) so this was a voyage of discovery. Careful bagging and labelling of each part has helped keep things ordered, but the next phase is the cleaning, de-rusting and replacement of missing parts before the rebuild can begin.

 

Just a selection of pictures from the strip down, but you get the idea.

 

Edited July 15, 2023 by GojuRyu5

[GojuRyu5]

Strip down complete, and at least a thousand YouTube videos later, I experimented with different ways to manage rust removal. Small parts seemed OK with a wire brush, elbow grease - a soaking in white vinegar seemed to help in advance.  But that wasn’t feasible for other, bigger parts. I read about the electrolysis method and set about putting something together. After a little trial an error to find the right materials for the sacrificial anode(s) and crocodile clips to manage connections, I have to say I have been impressed with the results.

 

After treatment for 24hr or so, most rust is removed from most pieces. Line of sight between the rusty parts and the anode helps, so I had to add further anodes, but with a production line set up, I have quickly managed to get through all the small and medium sized parts.  Each needs a wash, wire brush, a wet & dry paper rub down and thorough drying time afterwards, but I definitely feel like early progress has been made.  Many of the parts need to be painted afterwards so I have wrapped them all in paper and put them in bags to protect them from developing surface rust, before moving onto the painting phase a little later.

 

I ended up with a big 50L tub (old beer brewing kit) and two smaller 10L boxes for smaller parts.  I had to buy an older car battery charger (newer ones don’t like the process because they normally have ‘smart’ sensors to monitor charging. I also set up a very Heath Robinson spike board to accommodate the multiple crocodile clips in my circuits.  Seemed to work well.

[GojuRyu5]

This morning I have been working on the swing arm bushes which after 43 years were completely rusted solid.  I invested in a Sealey bearing puller, but no joy at all other than a newbie error of pinching my hand between the slide and the stopper - ouch!!

 

The bushes have a metal inner and outer lining, sandwiching a rubber core.  I tried heat, big hammers and in desperation I resorted to burning the rubber element out to release the inner part.  This worked (fortunately I have a blow torch and heatproof material to put around everything so I didn’t set the workshop on fire).  This just left the outer collar (whatever it’s called), and this was stuck solid.  The collet for the bearing puller just wouldn’t budge it, so the only way this was ever going to move was with a drift.

 

Working at an angle so I didn’t damage the inner surface of the frame, after about 20 - 30 minutes work on each side, they finally gave in and (thankfully) there was only very minor damage to the internal surface which will definitely come out with a gentle file (outside areas only) and light wet & dry rub down on the inside.  Job done!

 

Edited July 26, 2023 by GojuRyu5

[Mickly]

You sure you didn’t drag that out of the local cut?

[GojuRyu5]

I also had to remake a bracket from under the tank which the wiring loom hangs on. I needed some 1mm sheet steel, which was ‘reasonably’ easy to work but the company I ordered it from did at least cut a sliver off the side of the sheet for me so I didn’t have to worry about the width when I started. But the biggest issue was going to be the 1mm step in the bracket - difficult without a mechanical brake to bend it with.

Working with hand tools, including a sheet metal hand seamer, tin snips, hammers and files and taking one step at a time, the part slowly began to take shape.  I’m pretty pleased with the outcome.

I still find it amazing that with little prior knowledge, but some hand tools and patience, you can replicate a (relatively) simple part as part of a renovation.

 

Edited July 15, 2023 by GojuRyu5

[GojuRyu5]

On 15/07/2023 at 12:50, Mickly said:

You sure you didn’t drag that out of the local cut?

Well, to be fair, it looked mildly better on eBay, but if I can’t manage the restoration it doesn’t owe me much and I would have learned loads (especially not to buy bikes off eBay when you’ve had a couple of Guninnesses…).

Edited July 20, 2023 by GojuRyu5
Spellos

[Old-codger]

Hi there if you are interested I have some new old stock rear brake shoes for your little Honda that have been lurking in my shed for years. They are EBC304 shoes still in the box. I dont want anything just cant bare to chuck them away, if you are interested just drop me a pm.

[Fozzie]

I'm jealous of your bracket fabrication, how did you get that subtle L bend near the mount holes and the smooth curvature on those tangs? I've not been able to do stuff like that since I had all the tooling at college!

[GojuRyu5]

8 hours ago, Fozzie said:

I'm jealous of your bracket fabrication, how did you get that subtle L bend near the mount holes and the smooth curvature on those tangs? I've not been able to do stuff like that since I had all the tooling at college!

Hi Fozzie, and thanks.

 

All I had was a sheet metal hand seamer tool with which I made the first bend whilst the piece was clamped in a vice - and then tapped the bend to 90 degrees in the vice with small hammer to get a decent (but not too tight) corner.  Then I raised the piece in the vice by only about 2mm and bent the edge back on itself with the hand seamer again and I think I got lucky as it created an opposite bend and gave that step. I’d already shaped, drilled and filed the holes / slots but left removal of the main central material until afterwards so I didn’t weaken the overall structure of the tangs.

 

For the curvature, I had drawn the curve from the original piece so I knew what to go for, and had a piece of steel round bar handy (never throw anything away) which I clamped in a vice and just bent the tangs around it carefully, at first by hand and then with a small hammer to perfect the shape. 
 

Honestly, I surprised myself…. Photo of tools attached.

 

 

[GojuRyu5]

Today, I tackled the frame and started removing paint in prep for the electrolysis process on the whole thing to try to get as much rust off as possible before I resort to wet & dry paper and elbow grease.  I always say that it’s better to ask for forgiveness than permission, but have so far been lucky that the missus hasn’t noticed that I’ve ‘borrowed’ the wheelie bin for the job - it’s the biggest waterproof container I could find…

 

 

Edited July 20, 2023 by GojuRyu5

[GojuRyu5]

I wonder if I could ask for some  help / advice on a small welding issue, if anyone knows someone in the Dorset / Hampshire area?

 

On the frame I’m working on, there is a small flaw which I think is a small crack and would probably benefit from a simple tack weld.  I don’t know anyone who welds and don’t yet have the skills myself - future development opportunity.  Does anyone have any recommendations?  
 

Not the best picture, but you can just see the problem area.

[Stu]

That really is a minor issue

 

I would clean it all up straighten it out then find a local fabrication shop and pop in and speak to one of the welders to run a bead on it

 

They will probably charge you pennies for their tea fund then you can clean it all up yourself at home 

[Old-codger]

As stu has said find a local fabricators or smithy or old fashioned bike shop/car restorers in your area and for the price of a drink it will be done in the teabreak. Try and wire brush grinder clean up the area of all paint and rust so it is one less thing for them to do.

[GojuRyu5]

Thanks @Stu and @Old-codger. I’ll do a bit of research and see what I can come up with. You’re right, it’s definitely a small point.  The frame has been in the electrolysis wheelie bin since Thursday and is looking a lot better already. Once that’s done, I’ll get the wet and dry out, and then straighten the little kink before getting that beading done. Thanks for the thoughts boys.

[GojuRyu5]

Update on my frame.  My missus asked on FB for any recommendations for a local welder and a guy nearby who restores bikes (and, crucially, can weld) came round tonight and sorted the weld for me. When I asked how I could repay him, he said he was happy to help a biker. Top guy. Good progress.

 

 

Edited July 28, 2023 by GojuRyu5

[GojuRyu5]

So today I’ve been learning about plastic welding as one of the side panels had several cracks and a whole chunk of it was missing. YouTube is amazing for this stuff and I found an interesting video which gave me some ideas.

 

Using a soldering iron and some HDPE plastic (PP2) from a dustpan which I still have to explain to my missus, I managed to make the missing part and fill the cracks well. I also used some wire screen mesh to support the welds from inside which went very well. Followed this with some 2 part car body filler, and a good sand down and it came out OK.

Just applied the first coat of primer and the finish isn’t too bad. A few more coats and it’ll be ready for a silver top coat and new decals.

 

Restoration is a learning experience!!

Edited July 29, 2023 by GojuRyu5
Spello

[Ben_Jammin420]

Nice work so far.. doing an amazing job here Goju!  Certainly taking some of your techniques/methods for myself hope ya dont mind!

 

also noticed the dart board in the latest pic...do you play?  basically if not restoring parts I'm throwing darts while thinking of what to do next lol

[GojuRyu5]

On 05/08/2023 at 17:20, Ben_Jammin420 said:

Nice work so far.. doing an amazing job here Goju!  Certainly taking some of your techniques/methods for myself hope ya dont mind!

 

also noticed the dart board in the latest pic...do you play?  basically if not restoring parts I'm throwing darts while thinking of what to do next lol

Thanks bud. I’m a bit too much out of practice to be consistent but the board and the set up was an essential part of the workshop redesign over the winter. It was a good way to stave off the boredom before the CB project came along in May. 
At the moment it’s a drying rack for the Hammerite parts that are taking forever to cure… 

[GojuRyu5]

By way of an update, I’ve done some more work on the plastic side panel today to recreate the missing lug. Quite chuffed with the result.

 

 

[GojuRyu5]

Final colour of the side panel - just needs the final decals and clear coats then it’s all done.

 

 

[Fozzie]

There's something really satisfying, but also painful about bodywork. It takes an age to get it right, but it looks so good when it is done with patience

[GojuRyu5]

I have managed to get the primer, gloss and clear on 20 pieces of my CB, all now safely tucked away and am working through the second batch; another 16 parts on the go.

Spent most of yesterday rubbing down and preparing parts for painting and they’re looking OK for now, but because of the complex shapes I thought I’d hand paint (brush) Hammerite onto a couple - they really didn’t come out well, so had to start again and turn back to the Smooth Black spray version.  Much more pleased with that.

 

The side panels have had a clear coat and are ready for decals, although I’m not happy with one side and may start that again. You can only really tell after you’ve sprayed but I’ll be happier with a do-over on that one.

 

[GojuRyu5]

Also found a local welder who, in his words, likes a challenge and has agreed to have a go and repairing the rusty edge of my seat pan. Lovely guy, but the proof of the pudding is in the eating as they say. I’ll report back when he’s had a play.

 

The mudguards and rear wheel rims are at the re-chromers - but I’ll have to source a new front rim as that was beyond repair . He reckons they’ll be able to fit it in after 6-8 weeks… Then I’ll have to get my head around re-spoking them.

 

Slow progress, but progress nonetheless. I’m beginning to run out of parts to work on for now, but still have some challenges ahead. Sourcing a key - a local locksmith has agreed to have a look at the ignition and see if he can recreate the key for me - I can’t spray the tank until I can access the petrol cap so this is a big one.  However, in the meantime, the big job will be the frame - finish the rub down, prime and respray.  That’ll keep me out of mischief for a while… 

Edited August 25, 2023 by GojuRyu5

[GojuRyu5]

I have done the rework on the side panel; undercoat done, but final finish still needed.  Looks a lot better - needed to do that to give a decent base for the decals which arrive soon.

Before (in front of dartboard) and after.  The edge is now much more defined.  Still not perfect, but the top edge is under the seat edge, so is less visible,

 

[GojuRyu5]

So, some advice please if anyone has any thoughts?

 

I’ve decided to refresh the seals and oil in the front forks as part of the restoration. The manual says I need around 80cc of ATF, but I’m not sure of the suggested rating.  I am assuming that fork oil would be the best and assume that terminology has changed over time, but is there a specific oil rating anyone would recommend. Bear in mind it’s a CB100N so it’s a light bike and won’t be getting too much punishment.

 

Any thoughts?