CB 125J cafe racer restoration

Big day today. Worked on the bike from 10 to 16 'o clock sand blasting and putting the first primer on all head parts, swingarm and tank:

I decided to do the first layer on the tank to make sure it doesn't rust ... unfortunately my nozzle broke and the paint job got fucked up.

Satin black finish will go on this head once it's finished. Then i'll sand down the fins. Don't know what colour i'll do the fuel tank in.

Swingarm got its first layer of primer too, going to sand it and then respray it. However, I forgot to take the bushings out FML.

head by Mathias , on Flickr
tank by Mathias, on Flickr

The progress i've made on this absolutely terrible shredder-ready bike is amazing. This is so rewarding knowing that within an acceptable amount of time, this will be back on the road.
 
grcamna5 said:
That tank looks ready 8) Will you be using the stock 78' CB125J carb.?
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Yea. I have the original Keihin one here, cleaned it up (didn't sandblast it though and not going to paint.

The engine will get:
- A complete carb revision
- Complete engine cleanup and overhaul
- Complete head overhaul
- New air intake (K&N)
- 12V conversion
 
The crankcase is ok by the way. It's only on the left side and it's not even a mm. The cilinder wall is covering it anyway. I expect it not to affect the engine performance.

But then again I just might use the donor motor based on what the engine expert says.
 
mathiask said:
The crankcase is ok by the way. It's only on the left side and it's not even a mm. The cilinder wall is covering it anyway. I expect it not to affect the engine performance.

But then again I just might use the donor motor based on what the engine expert says.
Click to expand...

show us a pic of that area
 
IMG_20160102_112352 by Mathias , on Flickr

As you can see, It's not really indentation. It's more of an offset from the piston. So it's no harm :)

I have sanded and used putty today. Cleaned the tank interior one last time ( a lot of goo came out) and now filled the tank's sides with oil so rust won't settle until I finish painting the epoxy exterior.
 
IMG_20160103_130937 by Mathias , on Flickr

Done sanding everything on the tank (was nearly finished on the picture, not the finished product yet). I literally cannot understand the amount of dents. You see the long line of putty used? That's because some kind of chain-type thing hit the tank and just left really utterly small but annoying dents on the tank. The other dents were farely large. I tinned them and covered the rest up with putty.

The tank was yet again cleaned today with cleaning acid. A lot of shit came out after also mixing it with sand and thus internally sanding the thing. Last but not least, I put the water hose in there, pressurizing all the rost that was starting to peel off. After an hour or so, the fluids that came out of the tank started turning white. It's still not 100% clean on the inside, but getting it any cleaner would require me to just tear it apart.

And then I cleaned these bad boys:

IMG_20160102_130546 by Mathias , on Flickr


Does anyone know how to remove the shocks from the housing?
 
That fork tube you have there with the rust on it is already removed from the lower aluminum "housing" which I usually call the 'sliders' or lower 'case'.
The way to remove it from the fork tube is described in your Honda Factory Service Manual and that procedure needs to be carefully followed.I hope you have a Honda FSM because they give you the best information;another way to remove the lower sliders is to put the 'lowers' in a bench vise and have a friend pull outward on the upper chrome 'tube' which exerts pressure on the small rebound spring inside while you carefully use a power air or electric impact wrench with an allen head socket bit of the appropriate size that exactly fits your lower allen bolt on it and reverse the rotation to remove the bolt.They can be stubborn to remove by hand and a power impact wrench is usually required to remove it after sitting for so long;use care because it's easy to strip the head of the allen bolt in your fork 'lowers',the allen socket needs to be a tight fit.

I had my fuel tank(which is the same as yours)fully opened up at the bottom and then this great company here in Greensburg,PA. sandblasted the inside everywhere and checked for thin spots which usually happens with rust and especially if you do lots of rust removing treatments with acid and then they weld and strengthen those areas.Then they weld the two halves of the tank back together and apply a special,patented coating to the entire inside of the tank and bake it in an oven to fully cure it.The finished product is guaranteed for life.The website is: www.gas-tank.com
I will still have to re-paint my tank because they don't do that but I found a friend to do the job for me for $30 and I'll do the bodywork/dent repair myself because the outside was in good condition.
 
I see this time and again on the forums.
People need to start learning to crack those Allens loose and even remove them while they are still under the load of the bike. It greatly reduces the possibility of the damper rod spinning to almost none, and also empties nearly all the fork oil into whatever container you had ready to slide under the fork to catch it.
 
DohcBikes said:
I see this time and again on the forums.
People need to start learning to crack those Allens loose and even remove them while they are still under the load of the bike. It greatly reduces the possibility of the damper rod spinning to almost none, and also empties nearly all the fork oil into whatever container you had ready to slide under the fork to catch it.
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Right ;) that makes it a Lot easier later.
 
SOOOOOOOOOOOOOOO

the engine.

I received some criticism here for cracking open the crankcases. I thought, for such an old bike and for my own understanding of how the bike works, that it would be a good idea.

This is what I found

- Knock pins were gone
- Cam shaft was gone
- Valves were gone
- Second gear and the kickstarter gear was gone
- All seals were gone
- Chain tensioner was gone
- Cam sprocket had teeth missing
- Crankshaft bearing was gone
- Replaced some clutch plates
- Rebuilt clutch mechanism
- Tons of dirt on the inside

Finding these parts has been a real pain (without paying 100's). The entire engine has been rebuilt now. It's bored up two sizes, new piston and new piston bearings. Everything has been cleaned. Every rubber has been replaced and the gearbox is pretty much new. Total cost: 350 euros (I had a guy do the boring for me). The engine is brand new now though, so it's worth the money. I'll take a p icture when I polished the entire thing because it's still dirty and I need to repaint.

I also replaced pretty much all screws with stainless steel bolts to prevent the damage that was done to the engine block by people who don't know how to use a screwdriver properly.

I'm still thinking of repainting the block, because the entire rebuild process has left its marks on the block. I dropped some tools on the fresh paint job, which wasn't smart at all. I know. Working alone on this hasn't been easy, because my co-mechanics had their own projects to work on. It definitely caused me some sweat and worries, but I'm happy with the result. I thought about just buying a new engine, it made me doubt for a full month, but I decided this was best because then I could see that everything worked well and I wouldn't be surprised after 50 miles of riding that one of the gears is shit.

Next goals
- Revise fork tubes (or buy new ones) because the upper fork tubes are gone as another member indicated
- Finish paint job on the tank
- Paint the frame and swingarm (both are already in primer)
- Buy new rear forks
- Bolt everything back together
- Clean up the rims

28342245360_bf2d1df008.jpg


Elbow grease, yuck. Gonna take the tyres off, but leaving them on for now.
 
Mathiask,
Good to hear that you're bringing this little bike 'back from the dead' in a manner of speaking.. :D
There are some folks who literally take the life out of a bike but you're giving it new life. ;)
 
grcamna5 said:
Mathiask,
Good to hear that you're bringing this little bike 'back from the dead' in a manner of speaking.. :D
There are some folks who literally take the life out of a bike but you're giving it new life. ;)
Click to expand...
Yea, I just expected it to go a lot faster. But then again, the bike was too far gone for a quick rebuild... Any tips on getting the spokes clean? ;)
 
mathiask said:
Yea, I just expected it to go a lot faster. But then again, the bike was too far gone for a quick rebuild... Any tips on getting the spokes clean? ;)
Click to expand...

I take the wheels apart and re-assemble/true them later on.I take the spokes and use #0000 steel wool if they're not too rusty.. but if they are I sand the spokes down and paint them hi-heat silver and then bake them in an oven to hard-cure the paint.The better option is to replace them w/ new oem spokes.
 
The wheels won't be factory standard quality. I thought about plasti dipping them over the chrome, just out of laziness. But then again, I want to ride it first and then replace the spokes afterwards when the budget allows for it. The chrome is almost completely new on the rim itself, the spokes are pretty much grey now.

WhatsApp Image 2016-07-29 at 14.23.59
Elbow grease for three hours
 
Does anyone know what they did to put the paint on the frame? It's barely coming off with my air-compressed sand blaster and paint removal spray is only doing as much as is chemically possible.

It feels as if it's 8 coats of spray paint and 6 coats of clear coat.

Anyway, suspension is ready to go back into the frame ^_^ Ordering / buying a new steering wheel asap.

If anyone knows a slightly higher supension that will fit into my cb125j instantly, hit me up.
 
SL 125 shocks will fit and tighten up the front end geometry.
Get a good set that damp as well as boing and it's a nice ride.
TL 125 shocks are too long and too soft.
 
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