Author Topic: 1972 CB750 K2 Complete Restoration and Rebuild  (Read 4095 times)

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Offline pixlgeek

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1972 CB750 K2 Complete Restoration and Rebuild
« on: June 03, 2013, 12:22:49 PM »
I've finally found the time to begin my complete restoration of my 1972 CB750 K2.

It was purchased new by my father, driven until 1989 and then let sit outside for close to 25 years. My intentions are to restore it to factory condition to use as my daily driver/road tripper.

I also own a 2000 GS500E and 1981 Yamaha Virago 750 however I will be selling both of these to make space (spare change) for this restoration project.

This weekend allowed me to pull the bike out of the garage and begin the strip down. After removing a part I replaced the bolts in their positions to make it easier to bag and tag later. Currently, then engine has a frozen piston, in the upcoming weekend I will be using a mixture of ATF/Acetone as recommended by a few users on the board here to hopefully help free up the cylinders before I remove the engine from the frame.

First steps are going to be pulling the frame apart, blasting it and sending it off for powder coating. I've also been in touch with a vapor blaster here in the states that said he was more than willing to take on my 750 engine and crank case to get that factory fresh look out of the aluminum. I'm really looking forward to that step.

Here are a few pictures of the initial tear down. My goal is to have this bike mostly restored by Late July/Early August, I know that may be ambitious but if I don't set a goal for it, I will never get it completed.

I've pulled out the entire wiring harness except for the wires running through the handle bars to the tree. That will be completed this weekend as well. Any opinions on the quality of the wiring harnesses sold by PartsNMore?

I also want to replace all engine screws with hardened hex heads, any ideas or resources from someone that has done something similar? Any disadvantages to doing something like this?

Also just received my "My CB750 Book" which has already proven to be an invaluable resource combined with the Shop Manual.

Wish me luck folks, I look forward to working with all of you. :)

-George
« Last Edit: August 10, 2014, 04:45:36 PM by pixlgeek »

Offline lwahples

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #1 on: June 03, 2013, 12:39:36 PM »
Will be very interested in how this looks when done. Best part I see is a complete bike to start with.Too bad that it sat outside for so long.My 72 came in boxes and it wasn't till this spring I decided to build it.Most of the parts were traded away. Good Luck!

Offline SOHC4 Cafe Racer Fan

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #2 on: June 03, 2013, 05:48:16 PM »
Ambitious time frame. Go for broke.
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline jerry h

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #3 on: June 03, 2013, 07:03:40 PM »
That's cool that your able to work on your dad's bike -  too bad he didn't store it better.   Keep us informed on your progress! (take alot of pics as your taking it apart, you never know the little detail you will need to look up when putting it back together) ;)
"It is not the critic who counts, the credit belongs to the man who is actually in the arena, whose hands are covered with grease and oil."

K2 http://forums.sohc4.net/index.php/topic,105097.0.html

Offline iron_worker

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #4 on: June 04, 2013, 07:07:45 AM »
Unless you're working on this thing pretty much full time I just can't see july/august being even close to reasonable for a deadline. You've definitely got your work cut out for your. lol

IW

Offline SOHC4 Cafe Racer Fan

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #5 on: June 04, 2013, 04:07:51 PM »
Hey, come on IW!  Don't dash his hopes this soon.  I admire George's enthusiasm.  Maybe he can work on this full time and show everyone a kickass build in the time frame.  He may have MAD SKILLS and time to boot!!  Go for it!!  That said, George has some serious work cut out for him. 
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline kap384@telus.net

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #6 on: June 04, 2013, 07:14:09 PM »
Glad to see someone else restoring their Dad's motorcycle. Mine paled in comparison in terms of the effort required, but thanks for saving this one. You'll have a blast doing it!
1965 Honda CB450K0
1972 Honda CT70K1
1975 Honda MR50
1975 Honda CB400F Supersport
1977 Honda CB750F2 Supersport
1978 Honda XL100
1979 Honda CBX Supersport
1982 Honda VF750S Sabre - Adventure Bike modified
1983 Honda CX650T
1995 Honda VFR750
2016 Honda CRF1000L Africa Twin
2015 KTM 200 XC-W
1963 Suzuki T10
My 1977 CB750F restoration - http://forums.sohc4.net/index.php?topic=66779.0
My 1975 CB400F restoration -
http://forums.sohc4.net/index.php?topic=145196.msg1651779#msg1651779
'More Stock Than Not' thread - http://forums.sohc4.net/index.php?topic=90807.500
My CT70 Resurrection - http://forums.sohc4.net/index.php?topic=145221.0
Best Motorcycle Tool Ever - https://www.engduro.com

Offline pixlgeek

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #7 on: June 05, 2013, 01:54:44 PM »
Thanks for the positive motivation everyone!

Tonight I will be stripping, cleaning, and primer'ing the outside of the gas tank. I have POR 15 on its way and hopefully by this weekend I can get some muriatic acid on the inside of the tank and get this thing sealed up nice.

I'll post video/pictures later this evening of todays progress.

Offline K5owner

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #8 on: June 08, 2013, 02:46:05 AM »
Looks like a great  project. Start making a list of the parts you'll need, as they can take time to find. Good luck, look forward to following your progress.
-Ray
-----------------------------------------------------
Remembering the past...   Livn' the dream

1975 Honda CB750 K5, Restored Aug/2011
1971 Honda CB175 K5, next project
1977 Honda CT70, swap meet scooter
2004 Honda NRX1800 (Rune), Cruiser
1977 Honda GL1000, daily driver

Offline 70CB750

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #9 on: June 08, 2013, 04:22:10 AM »
Welcome!

I like your story - restoring your dad's motorcycle, how cool is that?
Prokop
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Pure Gas - find ethanol free gas station near you

I love it when parts come together.

Dorothy - my CB750
CB750K3F - The Red
Sidecar


CB900C

2006 KLR650

Offline Johnie

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #10 on: June 08, 2013, 04:37:17 AM »
A task like this with any other bike could be daunting...but the fact it was your father's bike will be inspiration enough to get it done. Great time frame, but don't let that get in your way. Don't even worry about a time frame. Most important thing is it looks like another 750 will be saved from the junk pile. Be sure to take a ton of pics during the tear down as you will be surprised how some things just do not seem in the right spot during the rebuild. Good thing is you have plenty of guys here with a bike like yours to help. Good luck and we will be following your progress...
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline edhaeuser

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Re: 1972 CB750 K2 Complete Restoration and Rebuild
« Reply #11 on: June 08, 2013, 06:57:29 AM »
Yours looks in similar condition to my K1 that I started restoring this winter.  I will be watching.  Good Luck!

I ordered the harness from Partsnmore.  I would buy another if I needed one, it seems to be good quality.  Here is a picture of the one I received from them.