Restoration Honda CB500K1 1972: Rebuilding the front fork Honda CB500K1

As I wanted to respray the frame of the bike, every part had to come off, including the front suspension. After removing the front wheel, front fender and brake caliper it's just a matter of loosening the triple tree bolts and pull the legs out...Easier said then done... The inner front legs didn't look too bad, minimal pitting, all straight, but when I tried to remove them from the triple tree the fun started.
Btw before you try to remove the forklegs, loosen all the bolts in the legs, like the top fork bolts, bottom allen bolt, drain plug bolt, etc.. It's way easier to do this when the legs are still hold by the triple tree.

Honda CB500K1 1972 frame

Honda CB500K1 front fork retainer

Honda CB500K1 front fork bottom allen bolt

Honda CB500K1 front fork rebuild

Honda CB500K1 removing front brake caliper

After loosening the triple tree clamp bolts that hold the inner legs in place I tried to pull them out but they wouldn't move an inch. I guess one of the previous owners tried the same before as both the fork top bolts showed evidence of hammering and other forms of abuse.
I drowned the ears/legs in WD40 and let it sit for a day or two... still no movement...

Then I carefully used a chissel as a wedge on the triple tree clamps and hammered on a piece of wood on top of the already damaged fork top bolts. Finally it came loose and I could pull them out of the triple tree and fork ears.
Damn.. the inner legs were totally pitted and rusted at the area that used to sit inside the fork ears.
Luckily you can buy perfect reproduction ones and that's exactly what I did.

Honda CB500K1 removing front forks from triple tree

Honda CB500K1 removing rusty front forks

Honda CB500K1 fork ears

Honda CB500K1 1972 fork ears

Next thing to do was removing the old silver paint (what was left of it..) and corrosion that was on the lower outer legs. I used the grinder with a brush wire wheel. I used a vice to hold the inner front fork as I was gonna replace that anyway, and that way it was easy to turn the lower leg while brushing of the old paint and corrossion. Be very careful and don't push too hard as the lower legs are made of aluminium and are very soft. I held the wire wheel in a 45 degree position and the corrosion and paint came of nicely without damaging the aluminium legs.

After draining the old oil trough the oil drain hole by pumping the legs a couple of times you can take the legs apart. This is pretty straight forward, especially if you've already loosened the bolts and nuts before the removal of the fork legs.

Honda CB500K1 separating inner and outer fork legs

Honda CB500K1 inner and outer fork legs

Honda CB500K1 fork legs top nuts

Another thing that had to come out of the outher leg was the fork oil seal. After removing the circlip you can just pry it out with a screwdriver. (Be careful not to scratch the aluminium inside of the leg).However it didn't wanna move. The old Honda seals are known for their resistance when you wanna pry them out but these were extremely stubborn and after a couple of hours I gave up trying to remove it with a srewdriver.

Honda CB500K1 fork leg seal and snap ring

Honda CB500K1 fork leg seal circlip removal

Honda CB500K1 fork leg seal snap ring removal

Honda CB500K1 fork leg snap ring groove

I grabbed some old parts in the shed and made a fork oil seal remover.
Start with a washer that's just a bit smaller then the oil seal and grind/cut of two sides. This way you can slide it underneath the metal lip of the seal. Mount the modified washer on a treaded rod with two nuts and slide it under the seal lip. The idea is to lift the oil seal out by srewing a nut on the other side of the rod.

First of all you need to create some travel for the washer/seal/nut combination so the top of the seal can at least get flush with the top of the outer leg. I used an old Volvo 122S wheel bearing part but other bits will work just as well.
On top of that I put another piece of metal that's bigger than the hole. When bolting the nut on the treaded rod the modified washer will evenly pull out the stubborn front fork oil seal.

Honda CB500K1 fork leg old seal removal tool

Honda CB500K1 fork leg old seal coming loose

Honda CB500K1 fork leg old seal finally out

Honda CB500K1 fork leg old seal coming loose

Honda CB500K1 home made fork leg seal removal tool

Finally got them out. Time for some sanding and light silver two pack.
I know a lot of people say the front legs of a Honda CB500K four were originally polished and then clear coated but there's also people saying they were painted a very light silver and then clear coated or the silvery colour came from the zinc that was used when moulding the aluminium forks back in the seventies.... Hmm... I'll go for the light silver paint which looks cool and is easier to maintain then polished forks.

Honda CB500K1 reassembling the front forks

Putting back together the front fork legs isn't too difficult. Make sure you've got a socket or similar to tap in the new oil seals. The oil seals have a top and bottom. The side with the two inner lips goes in first. The text on the outside is the top. Before you start pushing them in make sure you put some ATF on the mating surfaces. Also be careful to put the oil seals in perfectly flat (not on an angle). The seal should go below the groove for the snap ring. Again make sure it's not in an angle..

Honda CB500K1 new oil seals front fork

New oil seals front fork inside lips

Oil seals front fork text on top

Honda CB500K1 fitting new oil seals front fork

Fitting new oil seals front fork

After fitting the snap ring I put the spring in the new inner leg and slide it carefully through the fork seal into the outer leg. Then torque the 8mm allen bolt with ca. 14lbs-ft. Don't forget the copper washer.

Fitting new oil seals front fork

Next step is making sure the lock nut at the top of the spring is all the way in till the bottom of the thread. Then fill the fork leg from the top with 160ml ATF and close the fork with the shiny chromed fork nut. Actually I didn't do that and wait with the last step until the forks are bolted back on the bike. That way it's easier to torque the big fork bolts to spec (ca 45 lbs-ft)