Author Topic: Getting back to work on my K1  (Read 4064 times)

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Offline Tinman

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Getting back to work on my K1
« on: September 16, 2025, 03:21:09 PM »
   I've been doing rust removal on my gas tank, this like many sat for thirty plus years,it looked like napalm inside. I've used vinegar from the grocery store, I'm pretty happy with the results, it's now getting a final treatment of evaporust. I'm sure I'll have to coat it when I'm done. I've been a member for 15 years but haven't posted much but will be now that I'm set up to work on this bike. Tinman
Tinman

Offline HondaMan

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Re: Getting back to work on my K1
« Reply #1 on: September 16, 2025, 03:22:22 PM »
Go, Tinman!
Great start: my first 1971 750 had that same tank.
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book
Link to My CB500/CB550 Book: https://www.lulu.com/search?sortBy=RELEVANCE&page=1&q=my+cb550+book&pageSize=10&adult_audience_rating=00
Link to website: https://sohc4shop.com/  (Note: no longer at www.SOHC4shop.com, moved off WWW. in 2024).

Offline BenelliSEI

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Re: Getting back to work on my K1
« Reply #2 on: September 16, 2025, 03:43:44 PM »
Welcome back! If it doesn’t leak, don’t coat it.

Offline newday777

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Re: Getting back to work on my K1
« Reply #3 on: September 16, 2025, 04:22:44 PM »
   "final treatment of evaporust. I'm sure I'll have to coat it when I'm done.  Tinman

Like the Tinman.....use oil to treat the tank, 2 stroke oil works well.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 1 K2, 4 K6, 1 K8, 1 F1, 1 F3
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline pickleknuckles

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Re: Getting back to work on my K1
« Reply #4 on: September 16, 2025, 10:37:18 PM »
Makes me want another even more

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Offline Stev-o

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Re: Getting back to work on my K1
« Reply #5 on: September 17, 2025, 07:19:03 AM »
   ....looked like napalm inside.

"I love the smell of Napalm in the morning!"

                              - Lieutenant Colonel Bill Kilgore
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Online MauiK3

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Re: Getting back to work on my K1
« Reply #6 on: September 17, 2025, 07:49:13 AM »
"Smells like victory"

Agreed, if it does not leak, don't line it with anything.
More photos?
1973 CB 750 K3
10/72 build Z1 Kawasaki

Offline Dr. Frankenstein

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Re: Getting back to work on my K1
« Reply #7 on: September 17, 2025, 10:17:34 AM »
"...that smell...that gasoline smell..."

"Don't get off the boat."

Great movie!
« Last Edit: September 17, 2025, 10:19:42 AM by Dr. Frankenstein »

Offline Tinman

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Re: Getting back to work on my K1
« Reply #8 on: September 18, 2025, 07:32:07 PM »
Thanks gentlemen, the motor spins, about 120 lbs psi per cylinder. I'm cleaning the carbs, thank god for ultrasonic cleaners but they still need lots of manual labor. I do have spare coils from my two '76,'78 super sport bikes which I'm going to part out.
Tinman

Offline Kevin D

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Re: Getting back to work on my K1
« Reply #9 on: September 19, 2025, 06:40:55 AM »
Tinman, my own CB was stored for 15 years 1987-2002 with 2 inches of gasoline in the tank, my biggest mistake. I put hardware in the tank and shook it, rinsed it, repeated until clean. I got a new screen in the petcock. No sealer.
 Fresh gas and new battery and the bike started right up. Tank didnt leak. That screen is so fine it caught some debris in the bowl but it never got plugged. After a season of riding, there was just a tiny bit of debris in the bottom of the bowl. No leaks.
 Since then, the tank has been good for 20+ years 60,000 miles. It got a repaint in 2007 and came back better than new.
71 CB750 K1
108,000 miles
Original Owner
———past———
70 SL100/125/150
70 Candy BlueGreen CB 750 K0
————————————————-
Former Honda parts kid/counter kid/do all
—————————————————————-
Whether you think you can or think you can’t, you’re right
Genius is 99% perspiration, 1% inspiration

Offline Tinman

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Re: Getting back to work on my K1
« Reply #10 on: September 19, 2025, 07:27:42 AM »
Kevin, I think that's the next thing I'm going to do, I've seen someone on YT that's done just that. Thanks
Tinman

Online MauiK3

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Re: Getting back to work on my K1
« Reply #11 on: September 19, 2025, 08:03:11 AM »
Pictures!!
1973 CB 750 K3
10/72 build Z1 Kawasaki

Offline Kevin D

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Re: Getting back to work on my K1
« Reply #12 on: September 20, 2025, 12:06:56 PM »
The very early work that I did has no photos, sorry, just faded memories: there were a couple brass floats that were bad, replaced with plastic. A float valve or two, 5.5 mm fuel lines. I didn’t want to spring for a repaint for a bike that was no good but the bike was good and the repaint was terrific.
 A barbecue rotisserie was the preferred means to agitate the tank with hardware inside, I didn’t have one.
Lining the clothes drier with foam and giving your tank a spin was another means, I didn’t do that.
And I haven’t told you that I used a media blaster inside the tank, don’t do it.
I got a bunch of counter sunk wood screws with lots of sharp edges and put them in the tank and shook it until I couldn’t. I emptied the screws and the crud, rinsed till clean, repeated with screws and flush until no more crud.
 The paint was badly faded, there were knee rubs on the tank, the side covers were cracked.
Lots here that didnt “survive” , but the tank did.
« Last Edit: September 20, 2025, 12:38:45 PM by Kevin D »
71 CB750 K1
108,000 miles
Original Owner
———past———
70 SL100/125/150
70 Candy BlueGreen CB 750 K0
————————————————-
Former Honda parts kid/counter kid/do all
—————————————————————-
Whether you think you can or think you can’t, you’re right
Genius is 99% perspiration, 1% inspiration

Offline PeWe

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Re: Getting back to work on my K1
« Reply #13 on: September 21, 2025, 10:15:49 PM »
That color is really nice, Kevin.
So you still use stock side covers?

I thought they all become brittle and crack at removal due to age.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Kevin D

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Re: Getting back to work on my K1
« Reply #14 on: September 22, 2025, 04:49:13 AM »
The original side covers both cracked and were badly faded.
The reproduction replacements came from David Silver, LPM brand? Unpainted.
New grommets to hold them and much gentler handling these days.
The paint was mixed by a local guy as his side job.
DonDirtBiker Vintage Honda Paint, no longer in business.
It was applied by a friend/coworker Jim Nicholson, who did a masterful job.
Sadly, Jim has passed on.
« Last Edit: September 28, 2025, 05:21:33 AM by Kevin D »
71 CB750 K1
108,000 miles
Original Owner
———past———
70 SL100/125/150
70 Candy BlueGreen CB 750 K0
————————————————-
Former Honda parts kid/counter kid/do all
—————————————————————-
Whether you think you can or think you can’t, you’re right
Genius is 99% perspiration, 1% inspiration

Offline Tinman

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Re: Getting back to work on my K1
« Reply #15 on: September 22, 2025, 04:39:21 PM »
Kevin, thanks for the pics and tips for fixing the tank, here is a couple more pics of mine.
Tinman

Offline newday777

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Re: Getting back to work on my K1
« Reply #16 on: September 22, 2025, 05:00:13 PM »
Kevin, thanks for the pics and tips for fixing the tank, here is a couple more pics of mine.

😵‍💫🥺
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 1 K2, 4 K6, 1 K8, 1 F1, 1 F3
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline Mark1976

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Re: Getting back to work on my K1
« Reply #17 on: September 22, 2025, 05:13:36 PM »
   That tanks going to need some serious attention...
Start with the end in mind...

Offline HondaMan

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Re: Getting back to work on my K1
« Reply #18 on: September 27, 2025, 07:07:39 PM »
That color is really nice, Kevin.
So you still use stock side covers?

I thought they all become brittle and crack at removal due to age.

I've got several sets from FrankenFrankenStuff (in these forums). They are better than Honda's, with stronger and more resilient mounting tabs. First-rate parts!
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book
Link to My CB500/CB550 Book: https://www.lulu.com/search?sortBy=RELEVANCE&page=1&q=my+cb550+book&pageSize=10&adult_audience_rating=00
Link to website: https://sohc4shop.com/  (Note: no longer at www.SOHC4shop.com, moved off WWW. in 2024).

Offline PeWe

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Re: Getting back to work on my K1
« Reply #19 on: September 28, 2025, 12:20:44 AM »
That color is really nice, Kevin.
So you still use stock side covers?

I thought they all become brittle and crack at removal due to age.

I've got several sets from FrankenFrankenStuff (in these forums). They are better than Honda's, with stronger and more resilient mounting tabs. First-rate parts!
I ordered my side covers from Yamiya because they look like stock Honda ;D Maybe better plastic.
Painted and not painted.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline PeWe

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Re: Getting back to work on my K1
« Reply #20 on: September 28, 2025, 12:36:58 AM »
Kevin, thanks for the pics and tips for fixing the tank, here is a couple more pics of mine.
That tank looks very rusty.
Finding a better tank can be a better and in the end cheaper choice.

Painting the tank cost some, then find leaks means a waste of money, time and effort.

I do not trust liners either. Worth a try if tank looks really good on outside in stock or other good paint but has deep rust inside.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967