Author Topic: CB750 K2 Barn Find Restoration: Presents!  (Read 6195 times)

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Offline Lucien Harpress

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CB750 K2 Barn Find Restoration: Presents!
« on: May 22, 2016, 06:43:18 PM »
So.... bit of backstory.  I've rebuilt a couple of old motorcycles before, generally ones I through were pretty unique- 1984 GL1200 Standard (the last factory-naked Goldwing Honda made), a yellow '76 GL1000 (nobody bought them, so kind of rare), and a 1980 KZ1300 (Kawasaki's Big Six answer to the CBX).  Never a CB750 through- even though it's a classic, I never got around to it.

Until, obviously, now.

A buddy of mine had me check out a '72 CB750 he dug out of a barn.  It was.... rough.  It had set for nearly 30 years, about 20 of which it was exposed to the elements.  Lots of rust, lots of dirt, lots of issues.  But still- looks like it was all there.

He played around with it for about a month, then gave up and sold it to me.





So, as you can see, cosmetically it's not in the best of shape.  Also, there were some mods done by the PO to make it a bit of "Easy-Rider Lite".  Mini apes, and a sissy bar I already trashed.  Carbs were also replaced by the earlier K0 models (the ones driven by the "split-into-4" throttle cable).  I do have those, but would love a set of K2 period correct ones.



Moss on the crankcase.  Very nice.





But hey- how about some good news?  The motor turns over, and (far as I can tell) all 4 cylinders have compression.  Carbs can either be rebuilt or traded, and pretty much everything is there.  I've started digging into the electrical, and probably most of the switches will have to be replaced, but everything I need seems to be available. 

The goal is not a full restore (yet).  I just want to get it running, get it roadworthy, and put some miles on it before I get it pretty.  It's going to be a challenge, but I think I can do it.





Be prepared for a LOT of questions, though.  Never owed a CB at all, and even though I've got a manual coming, this should still be fun.
« Last Edit: June 04, 2016, 03:33:39 PM by Lucien Harpress »
-1970 CB750 K0
-1980 KZ1300
-1976 Yellow GL1000
-1965 CA77 "Dream"
-1997 Valkyrie
-1975 Velosolex

Offline Johnie

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #1 on: May 23, 2016, 09:44:23 AM »
Welcome to the forum. Looks like a nice find especially since it is not locked up which is a miracle if it was outside for a while. If you are taking it back to OEM get rid of those high rise bars too. Which would mean getting the OEM cables. What is the mileage and does it come with a title? How bad is the inside of the tank? Might want to start looking for the rear grab rail as those have been hard to find. I do have some of the parts you will need and will PM you. Good luck and keep us informed as to 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 Lucien Harpress

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #2 on: May 23, 2016, 11:39:40 AM »
Thanks for the replies.

Inside of the tank is exactly as crusty as you think it is.  What worries me most is the rust in the corners underneith it- I can just see those opening up like Swiss cheese the second I start cleaning the rust inside up.

Bars are already taken care of- I've got what I'm hoping is a set of OEM replicas correct for the year.  Apparently the K2 went with lower bars than either the K1 or K3?  In any case, it's what's going on.

It does have a title, and mileage seems pretty low- 10,217.  I'm not ruling out the odometer rolling over, but it DID sit since 1986, at least.

I got you e-mail Johnie.  Let me do some figuring on what I have, what's the priority of what I need, and maybe get you a pic or two.
-1970 CB750 K0
-1980 KZ1300
-1976 Yellow GL1000
-1965 CA77 "Dream"
-1997 Valkyrie
-1975 Velosolex

Offline CycleRanger

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #3 on: May 23, 2016, 12:13:32 PM »
There was a set of lower bars used on the K2 export models.
Do you have a copy of the Honda Shop Manual or Parts List for your bike? Get one here:
https://www.honda4fun.com/materiale/documentazione-tecnica
CB750K5        '79 XL250s     CL350K3
CB750K3        '76 XS650      '76 CJ360T

Offline rocket johnny

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #4 on: May 23, 2016, 07:21:42 PM »
nice find , a cool project .  welcome to the world of cb 750's .   its addictive  :)

Offline jerry h

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #5 on: May 23, 2016, 10:37:24 PM »
Welcome!

Looks like a good start to a project.  Curious... what's the month on the tag riveted on the steering head?

Kind of different, the PO replaced the handlebars, seat and added the harley rear wheel, but left the original exhaust!

Take care,
jerry
"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 CycleRanger

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #6 on: May 24, 2016, 06:52:30 AM »
Looks like it may have lowering blocks as well.
Do you have a copy of the Honda Shop Manual or Parts List for your bike? Get one here:
https://www.honda4fun.com/materiale/documentazione-tecnica
CB750K5        '79 XL250s     CL350K3
CB750K3        '76 XS650      '76 CJ360T

Offline Bankerdanny

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #7 on: May 24, 2016, 07:21:58 AM »
Based on the angle of that shock I think you are right.
"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline Lucien Harpress

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #8 on: May 24, 2016, 08:08:36 AM »
You would be correct.  You had me wondering, so I got to checking the back end, and sure enough- a set of blocks that offset the lower shock mounts about 4 inches to the rear.  Those are going on the pile next.  (Anybody want 'em?)

As far as the date stamp, I've got a manufacture date of 6/72, with a frame serial of 2049144 and an engine serial of 205688.  Definitely a K2 (if my internet skills were correct).

Still waiting on my ignition switch, but I'm wondering if it'd be worth pulling everything out of the frame and getting a coat of paint on it.  Nothing fancy, but enough to stop most of the rust....

Eh.  Looking's easy, work is hard.  It can wait.
-1970 CB750 K0
-1980 KZ1300
-1976 Yellow GL1000
-1965 CA77 "Dream"
-1997 Valkyrie
-1975 Velosolex

Offline Lucien Harpress

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #9 on: May 25, 2016, 02:58:36 PM »
Got my new ignition switch plugged in today, and lo and behold, more works than I would have thought!  In no particular order:

-Headlght (Hi beam only, but that's the fault of the light)
-Idiot Lights (Hi, Oil, Neutral)
-Start button (but not solenoid- just clicks.  Will spin the starter if you jump the posts.)
and most importantly...
-THE HORN!!!

What sucks is that the control switches that work (the right ones) are the ones that I have to replace, because they won't work with my new carbs.

Oh yeah, new carbs!  I managed to get a hold of a clean set of correct K2 carbs plus an airbox, simply for the cost of shipping my carbs to Wisconsin.  Not only that, all I need is a set of floats, which are comparable to a rebuild kit anyway. 

Forward progress is good progress.
-1970 CB750 K0
-1980 KZ1300
-1976 Yellow GL1000
-1965 CA77 "Dream"
-1997 Valkyrie
-1975 Velosolex

Offline edwardmorris

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #10 on: May 25, 2016, 03:03:38 PM »
........
I managed to get a hold of a clean set of correct K2 carbs plus an airbox, simply for the cost of shipping my carbs to Wisconsin....

Welcome. IINM, you had early K0 carbs on the bike, correct? If so, then that trade wasn't the best IMHO.

Offline Lucien Harpress

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #11 on: May 25, 2016, 03:16:58 PM »
Eh, for the condition they were in I think I did okay.  I'm not here to make money on this thing, I just want to get it running.
-1970 CB750 K0
-1980 KZ1300
-1976 Yellow GL1000
-1965 CA77 "Dream"
-1997 Valkyrie
-1975 Velosolex

Offline danyo

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #12 on: May 25, 2016, 03:25:56 PM »
I'm interested in those right side controls plus throttle tube. If you want sell those parts please PM me. Thx

Sent from my SM-N900T using Tapatalk


Offline Lucien Harpress

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #13 on: May 26, 2016, 12:49:42 PM »
Keep an eye out, dayno.  I might be getting back with you.   ;)

On a more somber note, it looks like I'm pulling the motor out sooner than I anticipated.  When I bought it we had been able to get out all of the spark plugs except the No. 2 one.  Well, after hitting it a bit more with everything I had lying around, it looks like the only way it's coming out is (hopefully) if I can get a straight-on angle on the thing.  I have yet to have a socket even grab the edges of the thing, and the frame in they way isn't helping.

It shouldn't be too bad.  Carbs and airbox is already out of the way- it really just looks like I have to drop the exhaust, can the drive chain (which is toast anyway) and hoist it out.

I've pulled a six-cylinder KZ1300 before.  A four-cylinder 750 should be a walk in the park.

Right?
-1970 CB750 K0
-1980 KZ1300
-1976 Yellow GL1000
-1965 CA77 "Dream"
-1997 Valkyrie
-1975 Velosolex

Offline CycleRanger

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #14 on: May 26, 2016, 01:01:38 PM »
There's several threads here about pulling the engine with examples of home-built solutions if you do some searching.
Don't feel bad about pulling the engine, you may be able to get away without doing an engine rebuild but to be safe to ride that bike needs to come down to the frame with forks and brakes rebuilt, triple tree bearings cleaned or replaced, wheel bearings replaced, swing arm serviced, etc.

« Last Edit: May 26, 2016, 01:03:43 PM by CycleRanger »
Do you have a copy of the Honda Shop Manual or Parts List for your bike? Get one here:
https://www.honda4fun.com/materiale/documentazione-tecnica
CB750K5        '79 XL250s     CL350K3
CB750K3        '76 XS650      '76 CJ360T

Offline Lucien Harpress

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #15 on: May 26, 2016, 05:52:09 PM »
Thankfully, I've already got an engine hoist (Harbor Freight special!), so the hardest part will be unbolting it.   8)

In prep for the engine pull, I decided to get the exhaust off. 



The good news?  I got the exhaust off, no problem.



The bad news?  I got the exhaust off....   :-\



I knew these pipes were going to be rough, but confirming it is always hard.  This is probably going to get replaced, but there's no way I'm spending the $1300 for a brand new set.  I'm probably just going to keep an eye out for individual pipes (either on Ebay or swap meets) and buy them as I'm able.  Until then I figure I'll re-use this, if only to get the bike running.

I also took the opportunity to get rid of the lowering blocks on the rear shocks.  The front end still looks wonky to me- does anyone have a measurement of the front fork length? 

I also noticed a (30 year old) oil leak from under where the head gasket is.  I'm contemplating replacing the head gasket while the motor is out, just because.  We will see.

In any case, forward progress. 
-1970 CB750 K0
-1980 KZ1300
-1976 Yellow GL1000
-1965 CA77 "Dream"
-1997 Valkyrie
-1975 Velosolex

Offline kslrr

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #16 on: May 27, 2016, 10:10:25 AM »
Following this build.
Now  1972 CB350FX (experimental v2.0)
        1981 CB650c Custom with '79 engine (wifes)
        1981 CB650 engine
        2004 HD XL883C Custom
        1977 Yamaha XS750D (in progress)
Then 1972 CL175
        1964 Yamaha YGS-1T
No ride is a Bad ride

Offline Lucien Harpress

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #17 on: May 27, 2016, 03:04:07 PM »
You know what looks really weird?  Brand new handlebars on a POS barn find hunk of rust.   ;D





I got these from vintagecb750.com, and while they say they are year-specific to the K2, they still seem quite a bit lower than I was expecting.  Still, they probably won't be bad at speed (assuming that ever happens), and this isn't going to be a long-distance bike anyway.

Obviously this means all new cables and lines, but that was something that needed to happen anyway.
-1970 CB750 K0
-1980 KZ1300
-1976 Yellow GL1000
-1965 CA77 "Dream"
-1997 Valkyrie
-1975 Velosolex

Offline Davez134

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #18 on: May 27, 2016, 05:57:39 PM »
I can measure the forks on my k2 when I get home. What do you need? Just a simple measurement from the caps to axle as bike sits?

Offline Lucien Harpress

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #19 on: May 27, 2016, 06:13:17 PM »
Yup, that will be more than fine.  I'm thinking that if the front forks are off, they'll be off by quite a bit, so an exact measurement isn't really necessary.  Just let me know your endpoints (I figure middle of the axle to the top edge of the caps, not including the raised hex portion) and that should be good enough.

Maybe it's the front tire being completely flat that still throwing me off a bit, but ever since I raised the back end back to stock, the front looks wonky.

Thanks!
-1970 CB750 K0
-1980 KZ1300
-1976 Yellow GL1000
-1965 CA77 "Dream"
-1997 Valkyrie
-1975 Velosolex

Offline 754

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #20 on: May 27, 2016, 06:44:39 PM »
 Try the stock sparkplug wrench, others may not fit.
 If you cut the frame and add a frame kit, you can pull the topend out , leaving the lower end in the frame.
Does the right side switch have a red, or black kill switch ?
 You may get away with only changing lower half of switch and throttle tube.
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Kelowna B.C.       Canada

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It's All part of the ADVENTURE...

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Lost quite a few CB 750's along the way

Offline Davez134

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #21 on: May 27, 2016, 07:38:50 PM »
Just using a tape measure, it's right about 30 inches from axle center to top of fork, not including raised portion as you asked. Bike on center stand.

Offline SOHC4 Cafe Racer Fan

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #22 on: May 27, 2016, 07:59:29 PM »
I like the lower bars.
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 Lucien Harpress

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #23 on: May 28, 2016, 05:46:25 PM »
Davez134- Hm.  30 inches is about what I got on mine.  Guess they just dropped the back end, and my flat tires are throwing me off.  Thanks for that!

754- Thanks for the advice.  I don't have the stock spark plug wrench, but this isn't the first time I've heard this advice.  I may have to track one down.  It's still worth pulling the motor though, because I'm noticing a big oil stain on the front of the block, originating at the head gasket.  I hear this is somewhat common, but it's probably a good time to change that head gasket anyway.  (Normally I'd wait, but I didn't expect to pull the motor this quick.)

I also didn't think about just replacing the bottom of the switch.  Far as I can tell, all the rest of it works, so this would save me quite a bit of cash.

At some point soon, my exhaust is going to be for sale.  I picked up a decent set on ebay not too long ago, so I don't need the pipes I have now.  Problem is, whoever designed the header-to-block connection on the 750 really.... dropped the ball (to keep it family-friendly).  Way over-complicated, Phillips screws for the connection (or JIS, whatever), and perfectly designed to rust and weld themselves together after sitting for longer than about 5 minutes.

Once I get the header connection pieces off, I'll post something up in the Classifieds forum.

Until next time!
-1970 CB750 K0
-1980 KZ1300
-1976 Yellow GL1000
-1965 CA77 "Dream"
-1997 Valkyrie
-1975 Velosolex

Offline pipeguy

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Re: CB750 K2 Barn Find Restoration (hopefully)
« Reply #24 on: May 29, 2016, 03:35:02 AM »
Watching this one!
1970 CB750 K0 
1980 CBX
2001 Electra Glide
2013 CRF450R
2013 KX450F
 
1977 KH 400 triple (gone)
1973 CB750 K3 (waiting it's turn)
2000 KLR 650(gone)
2001 BMW 1200RS(gone)
2004 Busa limited(sadly gone)
2003 ZZR250 ninja(gone)
1996 VFR750(gone)
1974 RD350(really sadly gone)