Topic: CB750K2 '72 Resto

[Vidgameking]

Alright, I've got it figured out! I've cleared a work area for the bike in my shed and I'll work on it there. Also I've carved out the 5am to 7am slot every day to work on the bike (only time I have really).

With that said; this morning I got the seat, side covers, and tank off the bike! I also pulled the air filter. I never replaced the air filter, but the one in there seems pretty nice. I'm not sure if the PO put this one in because it's not stock. Do you all think it's worth keeping or should I grab a K&N to put into the stock air box? Also on the bottom of the seat I found a user manual for the bike and I have a complete tool kit that's also in really good shape!

I want to get to the point where I can tear out the carbs and start cleaning them. I tried moving the throttle actuator at the carbs themselves with the linkage still connected, and it still feels like it's binding up somewhere. I'll have to pull the carbs to get a better understanding of what is going on there. Good news is the carb dust covers in the middle of the bike are actually in really good shape so I will re-use those and only replace the outer two.

Inside of the tank is mostly clean, the gas is old and stinky so that will get flushed. I'll be clearing the rust as well. I had to cut the fuel lines to get the tank out, I'm not sure if I should get a new petcock valve or just clean out the old one.

[Vidgameking]

tested Electrolysis last night as well. I wanted to figure it out because I will be using it all over the place with this bike.

I have a 55-gallon plastic drum I'll be using to submerge large items into.

What items can I use this with? I was thinking about both aluminum (carefully) as well as chrome parts.

Rims, mufflers, bolts and stuff, fenders, what else?

here is my test set up:

5-Volt 10-Amp bench power supply (power filtered for constant consistent flow no need for battery in-line)
rebar Cathode
12-guage copper wire to inter-connect items
Soda Ash Pool additive (Pure Sodium Carbonate)
for testing I did a rust hatchet.

[SOHC4 Cafe Racer Fan]

I don't think you want to use electrolysis for aluminum parts.  You can polish the oxidation from aluminum. 

[Tews19]

I don't think you want to use electrolysis for aluminum parts.  You can polish the oxidation from aluminum.

What Don said! Aluminum is easy to make pretty .

[Vidgameking]

I have the stock exhausts on the bike, and they have small bits of rust on them, just little bits here and there. I was thinking about electrolysis to remove the rust or should I buff it out gently? Also the over-all condition of the pipes is pretty good, no week spots, just minor rust spots from storage. Can I get them re-chromed?

Lastly what about selling the pipes to fund the project? I'm okay with a 4-into-1. Would the pipes fund a new exhaust plus $600+/- on parts to get her running again?

[SOHC4 Cafe Racer Fan]

I am not sure how electrolysis affects chrome plating.  You may just send them out for re-chroming, but plating shops are scarce these days. 

[Johnie]

And a lot of the chrome shops will not do used exhaust as the carbon damages the plating chemicals. Without really seeing what you have there for rust, I would try some 0000 steel wool and WD40 on the rust. I have good results with that on the chrome parts. Besides, chrome is very expensive and you probably want to hold back on the $$$ until you see how she runs.

[Vidgameking]

Alright, Got the airbox off the carbs and was able to for the first time look in and see what I'm working with.

I've found it looks like Carb #2's slider is stuck and this is causing the stiffness in the throttle. I decided I will order new cables anyways so I cut the cables at the carbs and confirmed the throttle grip works fine. I'll still need to clean up the control pod up there due to the leaked brake fluid but at least I know the throttle grip works!

There is a dried pool of varnish on Carb #1 I believe this was the carb that was leaking fuel before I stored the bike but Carb #2 has a lot of varnish in it as well. Tomorrow I'll pull the carbs completely off the engine (using a hair drier to heat the rubber first). I'll pull all the rubber and soak the whole assembly in PineSol and then start tearing into things and trying to figure out what needs fixing and what needs replacing.

Concerning Carb #2, if for some reason some part of the carb has died a miserable death and thusly caused the carb itself to die, can I replace just the carb itself or will I need a whole new set?

I'm considering buying a used set on eBay anyways just to use for spares. I know I'll have to find one specific for the K2 I have.

[Vidgameking]

Pulled the rubbers off the engine and got my first look into how the inside of the engine might look! It looks dang near squeaky clean to me, I was worried about buildup and debris on the intake on the head as well as what I saw on the carbs. There is some minor white corrosion marks from the aluminum but other than that things look good! I'm going to do a compression test at a later time on the cylinders to validate that.

[Vidgameking]

Pulled the bowel off carb #4. Look at the needles in the bowel! The gasoline has formed orbs of varnish!! Weird!

[Tews19]

That's normal.  It's old gas. Nothing a good cleaning can't fix.

[Vidgameking]

Polished up one of the carb bowels tonight. I just wanted to see how much I could do by hand here. I soaked the bowel in 91% alcohol and then used a tooth brush to clean the rest of the varnish out. I then washed carefully under hot water. Then I dried it completely out. Then I wet sanded 400-600-1500-3000, then polished with buffing compound. I then buffed with a fuzzy and soft towel. I know a polishing wheel can buff to a crazy shine but I think this is good enough for me. Now I have to do it three more times!

[Vidgameking]

Carb bodies cleaned up nicely!

Used alcohol to soak the carbs, then scrubbed with tooth brush and simple green.

[Tews19]

The second to last pic, it looks as if the emulsion tube is still in the body. If it is remove it, clean out that orifice and of course the tube.

[Vidgameking]

Finished cleaning the Carbs! OH MEH GOSH!!! It was a bit harder than I thought it would be. Mostly on account of the harsh chemicals and the stink of old gas. Looking forward to the rest of the bike being a significantly less smelly task.

[SOHC4 Cafe Racer Fan]

Finished cleaning the Carbs! OH MEH GOSH!!! It was a bit harder than I thought it would be. Mostly on account of the harsh chemicals and the stink of old gas. Looking forward to the rest of the bike being a significantly less smelly task.

Just wait until you smell old fork oil!!