Author Topic: 1972 CB 750 restoration after a 40 year nap (Read 16940 times)

oldhatt45 · « **Reply #25 on:** October 18, 2015, 06:12:16 PM »

autotec,

It is looking pretty good. May not take too long.

When you're done with the vinegar, don't forget to rinse it with Baking Soda (like the Arm & Hammer stuff).
Don't seal the tank or it will expand from the reaction of gases.
Then rinse with water and give it a coating to prevent flash rusting. Possibly Marvel Mystery Oil, or fill it up with gas.
One of the experts will chime in i'm sure.

Charlie

autotec · « **Reply #26 on:** October 18, 2015, 07:11:04 PM »

I figured while I was waiting, I would check the electrical system. F&R brake switches work, L&R turn signal work. The only issue I see is the starter button is missing. So I will need a new switch set. No big deal.

Stev-o · « **Reply #27 on:** October 18, 2015, 07:21:42 PM »

Clean is good.

BTW - the back rack/sissy bar and the front crash bars are not stock items, the bike will look much better w/o them.

autotec · « **Reply #28 on:** October 18, 2015, 07:33:00 PM »

Quote from: Stev-o on October 18, 2015, 07:21:42 PM

Clean is good.

BTW - the back rack/sissy bar and the front crash bars are not stock items, the bike will look much better w/o them.

I totally agree. There is a time and place for certain things, and these just don't fit. Here are my current bikes.

edwardmorris · « **Reply #29 on:** October 18, 2015, 09:07:10 PM »

Quote from: autotec on October 18, 2015, 07:11:04 PM

I figured while I was waiting, I would check the electrical system. F&R brake switches work, L&R turn signal work. The only issue I see is the starter button is missing. So I will need a new switch set. No big deal.

No need to buy the whole control unit, the button is still available from Honda. As you may have seen, K2 has simplified electrics. You'll need these two parts to get the start button back

SPRING, BUTTON
35318-259-000

BUTTON
35317-001-310

754 · « **Reply #30 on:** October 18, 2015, 09:34:17 PM »

Your switch wires appear to be inside the handlebars. That is stock.
Bad part, they are likely extended, you may have to replace bullet connectors and maybe add wire.

Restoration Fan · « **Reply #31 on:** October 19, 2015, 10:11:19 AM »

Nice bike! It's going to be really special for you too because of the family connection!

Looking forward to seeing this one back on the road. By the way, the gold ones are the fastest!

autotec · « **Reply #32 on:** October 19, 2015, 12:11:24 PM »

Quote from: Restoration Fan on October 19, 2015, 10:11:19 AM

Nice bike! It's going to be really special for you too because of the family connection!

Looking forward to seeing this one back on the road. By the way, the gold ones are the fastest!

Thank you. I heard that about the gold ones, LOL.

autotec · « **Reply #33 on:** October 19, 2015, 06:08:00 PM »

Well I got home from work and drained the vinegar solution out of the tank, then immediately flushed it with some fresh gas. I'm mostly happy with the outcome, but there is some sludge trapped at the bottom in the corners. I flushed it 3-4 times and it's slowly coming out, it's just going to take some more time and gas. (I'm out of gas) Below are the before and after pictures. Time to remove the carbs.

754 · « **Reply #34 on:** October 19, 2015, 06:50:10 PM »

Did you rattle it with a few nuts and screws... May harm petcock. Gets most of the corner stuff out.
I drained mine by holding upside down, then positioned so the lttle bit left was furthest away from petcock, then used a suction pump to suck out the rest..

autotec · « **Reply #35 on:** October 19, 2015, 07:59:28 PM »

Quote from: 754 on October 19, 2015, 06:50:10 PM

Did you rattle it with a few nuts and screws... May harm petcock. Gets most of the corner stuff out.
I drained mine by holding upside down, then positioned so the lttle bit left was furthest away from petcock, then used a suction pump to suck out the rest..

Doing that now, after a quick clean-up with a wire brush attached to a brake line for extra length. So far it looks like the stuff wipes right off, if I can get to it. I'll let you know how it goes.

Thanks, Justin

autotec · « **Reply #36 on:** October 19, 2015, 08:08:19 PM »

Finally got the carbs off and the bowls removed. As expected after 40 yrs of storage, I'll clean them tomorrow. I want to try something new at work with them. A vapor ultrasonic cleaner.

guitarkev66 · « **Reply #37 on:** October 20, 2015, 07:26:51 AM »

does your engine start with a 200 or 201 number? just curious.. I too have a 11/71 k2 mine is 2004090 and has a 201 engine number

autotec · « **Reply #38 on:** October 20, 2015, 08:54:15 AM »

Quote from: guitarkev66 on October 20, 2015, 07:26:51 AM

does your engine start with a 200 or 201 number? just curious.. I too have a 11/71 k2 mine is 2004090 and has a 201 engine number

It starts with 201, not sure if you can see it in the picture though.

Sgt.Pinback · « **Reply #39 on:** October 20, 2015, 10:59:17 AM »

Great bike!

guitarkev66 · « **Reply #40 on:** October 20, 2015, 05:45:55 PM »

yea, mine is 2011818. I'm trying to figure out when they jumped engine numbers from 200's to 201's. my guess is 10/71

autotec · « **Reply #41 on:** October 20, 2015, 06:22:51 PM »

And I thought the tank was almost clean, boy was I wrong. Some of those deposits left in the corners were more than a half inch thick. I don't think it is rust, I think it's just old gelled gas. The more I flush with new gas, the more comes out. I'm just going to keep flushing until the gas comes out of the tank clean. The picture below just shows how much umm crap I got out today.

autotec · « **Reply #42 on:** October 20, 2015, 07:25:51 PM »

Getting my daughter involved, removing the engine guard, back rest and luggage rack. It's amazing how much smaller the bike looks now. On a side note, she actually likes all of those pieces on the bike. She says it makes it look vintage, so I think I'll clean them up and hang onto them.

autotec · « **Reply #43 on:** October 20, 2015, 07:41:09 PM »

Good news, my uncle found the original title for the bike. That will make registration so much easier here. He also brought me a few parts he found in his garage. Small service manual is a plus, points won't be used since I plan on going with electronic ignition. But when was the last time you seen an oil filter for $2.20?

autotec · « **Reply #44 on:** October 20, 2015, 08:02:12 PM »

I searched, read, searched some more but I couldn't come up with a answer. On the left controls, there is a second push button under the horn push button. What is that for? With the battery hooked up, I can't seem to find a function for it.

Thanks, Justin

Stev-o · « **Reply #45 on:** October 20, 2015, 08:35:09 PM »

It is a turn signal cancel switch. K2 is the only model to have it.

autotec · « **Reply #46 on:** October 20, 2015, 08:44:47 PM »

Quote from: Stev-o on October 20, 2015, 08:35:09 PM

It is a turn signal cancel switch. K2 is the only model to have it.

Ah, thank you. Mystery solved, at least for me.

Thanks again, Justin

mrbreeze · « **Reply #47 on:** October 20, 2015, 08:49:21 PM »

Quote from: autotec on October 18, 2015, 06:05:10 PM

While I'm waiting on the tank to un-rust, I figured I would clean the bare bike so the dissassembly would be cleaner. (if that's a word) The only issue I ran into was the removal of the plastic side covers. After 40 years. they did not want to come out. But with a coating of silicon lube, they finally came out without breaking. After a degreasing, I was impressed with the finish on everything. It almost looks new. Almost.

Good to hear they didn't break but don't press your luck. I'll bet the grommets are hard as a rock but new ones are still available. Not sure about the 72 but mine (75) has 2 out of the 6 grommets a different size (upper left cover). Make sure you get 4 of one size and 2 of the other. Also, I would still use lube to install the covers because if the covers break you won't be a happy camper!

calj737 · « **Reply #48 on:** October 21, 2015, 04:16:36 AM »

make sure you de-rust the filler cap too. And insure the vent is open and clear. You may find it useful to carefully your Acetone into the tank to release the sludge build-up in the corners. You need to keep the tank somewhat sealed as the Acetone will evaporate pretty quickly, but it does eat the sludge. A few 12mm stainless nuts dropped in and shaken around help too. They're easy enough to get back out by inverting the tank afterwards and rattling them out.

gwallis · « **Reply #49 on:** October 21, 2015, 05:08:51 AM »

AutoTec,

Here are the best two pieces of advice I can give on dealing with rust.

Use a Toilet Bowl Cleaner called 'The Works - Basic' in order to get all of the rust out of the gas tank. Search YouTube for related video.

I also use 'Marvel's Miracle Oil' and steel wool to clean rust pitted chrome parts. In fact, whenever I buy a used bike I wipe the entire bike down with Marvel's as I disassemble it.

I hope this helps.

Gary

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Author Topic: 1972 CB 750 restoration after a 40 year nap (Read 16940 times)