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Author Topic: 1978 CB750 K8 project  (Read 8736 times)

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Offline martin_uk

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1978 CB750 K8 project
« on: February 25, 2015, 08:20:12 AM »
I bid on this on Ebay, despite having a complete F1 and 2 F1 projects  ::)

Got it for a reasonable price, but quite a few bits missing.

Picked up at beginning on December last year.

CB750K8 purchased eb by nitram2010, on Flickr

CB750K8 purchased eb$_57 by nitram2010, on Flickr
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #1 on: February 25, 2015, 08:23:58 AM »
The good thing is not knowing what you are going to find and the bad thing is not knowing what you are going to find :P

CB750K8 purchased eb 1$_57 by nitram2010, on Flickr

003 by nitram2010, on Flickr

004 by nitram2010, on Flickr
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #2 on: February 25, 2015, 08:29:00 AM »
I do quite like the strip down

2014_1206Kparts0043 by nitram2010, on Flickr

2014_1206Kparts0034 by nitram2010, on Flickr

2014_1206Kparts0020 by nitram2010, on Flickr

2014_1206Kparts20111 by nitram2010, on Flickr

2014_1206Kparts20108 by nitram2010, on Flickr

I am some way into project and this is just a catch up.
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #3 on: February 25, 2015, 08:38:00 AM »
ahh so thats what colour it started as  :-\

2014_1206Kparts20094 by nitram2010, on Flickr

The US sun has taken its toll on the paint and plastics, it had better get used to the UK climate  ;D

Lots of ferrous oxide!

2014_1206Kparts20087 by nitram2010, on Flickr

Another missing bit

2014_1206Kparts20079 by nitram2010, on Flickr

Very crusty

2014_1206Kparts20074 by nitram2010, on Flickr

2014_1206Kparts20055 by nitram2010, on Flickr

Getting bits ready for blast and powder coat

2014_1208Kparts50049 by nitram2010, on Flickr

2014_1208Kparts50046 by nitram2010, on Flickr

2014_1208Kparts50040 by nitram2010, on Flickr



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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #4 on: February 25, 2015, 08:52:22 AM »
Parts ready for plating

2014_1214partstosell0048 by nitram2010, on Flickr

2014_1214partstosell0047 by nitram2010, on Flickr

2014_1224kparts80011 by nitram2010, on Flickr

inside air box

2015_0103armse0019 by nitram2010, on Flickr

2015_0103armse0018 by nitram2010, on Flickr

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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #5 on: February 26, 2015, 09:18:05 AM »
Tank blasted and etch primed but has fuel residue in form of thick brown sludge.

2015_0209frame0001 by nitram2010, on Flickr

Left fresh petrol to soak, but would not shift.

Used cellulose thinners in the end.

2015_0209frame0002 by nitram2010, on Flickr

Took a long time to keep flushing

2015_0209frame0004 by nitram2010, on Flickr
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #6 on: February 26, 2015, 09:21:36 AM »
Seat base is quite badly rusted and will need alot of work to repair.

2015_0119frame0073 by nitram2010, on Flickr

I cant find anyone listing the K8 seat cover with raised pillion section, anyone know of a good supplier?
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #7 on: February 26, 2015, 09:24:54 AM »
Found that rear fender wrong one  :'(

2015_0207frame0020 by nitram2010, on Flickr

Anyone know what this holder is for?

2015_0207frame0021 by nitram2010, on Flickr
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #8 on: February 26, 2015, 09:32:50 AM »
Wheel spokes too rusty

Can get new spokes and new front rim from DSS but not 17 inch rear so reusing

2015_0126frame0041 by nitram2010, on Flickr

Have not seen this type of very thick rubber rim tape, is it a US standard?

2015_0119frame0079 by nitram2010, on Flickr

2015_0119frame0078 by nitram2010, on Flickr

Had to cut some of spokes to get off

2015_0126frame0087 by nitram2010, on Flickr
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #9 on: February 27, 2015, 12:15:23 PM »
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #10 on: February 27, 2015, 12:24:45 PM »
Engine coming apart

2015_0215engine0053 by nitram2010, on Flickr

Lifting out starter motor

2015_0215engine0049 by nitram2010, on Flickr

2015_0215engine0046 by nitram2010, on Flickr

Oil filer looks OK

2015_0215engine0027 by nitram2010, on Flickr

2015_0215engine0023 by nitram2010, on Flickr

2015_0215engine0013 by nitram2010, on Flickr

2015_0215engine0012 by nitram2010, on Flickr

2015_0215engine0010 by nitram2010, on Flickr

Brown dust everywhere

2015_0215engine0006 by nitram2010, on Flickr

2015_0215engine0079 by nitram2010, on Flickr

Bearings look good

2015_0215engine0081 by nitram2010, on Flickr
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Offline SOHC4 Cafe Racer Fan

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Re: 1978 CB750 K8 project
« Reply #11 on: February 27, 2015, 03:16:10 PM »
A wee bit crusty on the outside but not bad inside.
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"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)

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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #12 on: February 28, 2015, 02:31:32 AM »
Frame powder coated

2014_1212Kparts60002 by nitram2010, on Flickr

2014_1212Kparts60004 by nitram2010, on Flickr

Zinc plating done

2014_1224kparts80016 by nitram2010, on Flickr

2014_1224kparts80015 by nitram2010, on Flickr

2014_1224kparts80014 by nitram2010, on Flickr

2014_1224kparts80013 by nitram2010, on Flickr

Managed to get hold of a NOS exhaust ;D

Just need a Left Upper (no1) HM405 marked SL if anyone has?

2015_0101exhaust0003 by nitram2010, on Flickr
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #13 on: February 28, 2015, 02:37:05 AM »
Quote from: CB750 Cafe Racer Fan on February 27, 2015, 03:16:10 PM
A wee bit crusty on the outside but not bad inside.

It is a bit like a lucky dip when buying a non runner with unknown history :) But all part of the fun!

Found a piston circlip in crankcase and a seized/broken points cover screw, but apart from new sprocket, seals a clean up repaint and replating fixings the bottom end seems pretty good.


Usual damage on alternator cover, but not broken.

Will strip oil pump shortly.
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Offline Restoration Fan

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Re: 1978 CB750 K8 project
« Reply #14 on: February 28, 2015, 05:38:37 AM »
Martin,
The frame and those bolts look really good.  Did you do the zinc plating yourself?

Ron
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Ron

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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #15 on: February 28, 2015, 11:51:49 AM »
Quote from: Restoration Fan on February 28, 2015, 05:38:37 AM
Martin,
The frame and those bolts look really good.  Did you do the zinc plating yourself?

Ron

No, I prep by electric wire brushing and have a local co that does at reasonable cost.
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #16 on: February 28, 2015, 11:58:30 AM »
Switches done, found another kill switch knob, cleaned contacts and painted

2015_0219switch0015 by nitram2010, on Flickr

2015_0219switch0014 by nitram2010, on Flickr

2015_0219switch0012 by nitram2010, on Flickr

2015_0219switch0017 by nitram2010, on Flickr

2015_0219switch0018 by nitram2010, on Flickr
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #17 on: February 28, 2015, 12:03:21 PM »
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #18 on: February 28, 2015, 12:12:55 PM »
Rear wheel with new spokes

2015_0128frame0013 by nitram2010, on Flickr

New brake shoes

2015_0207frame0036 by nitram2010, on Flickr

Brake caliper overhauled

2015_0207frame0037 by nitram2010, on Flickr

Cleaned and painted rear mudguard before finding it was wrong one  :-[

2015_0207frame0012 by nitram2010, on Flickr

So made an extension plate

2015_0209frame0011 by nitram2010, on Flickr

2015_0214frame0012 by nitram2010, on Flickr

2015_0214frame0026 by nitram2010, on Flickr

2015_0214frame0029 by nitram2010, on Flickr

2015_0214frame0036 by nitram2010, on Flickr
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #19 on: March 01, 2015, 02:23:58 AM »
Started on head yesterday

2015_0228eng0011 by nitram2010, on Flickr

Most of valves were semi seized and seals rock hard

2015_0228eng0015 by nitram2010, on Flickr

2015_0228eng0018 by nitram2010, on Flickr

Cleaned up valves

2015_0228eng0023 by nitram2010, on Flickr

Looking better, but such a messy job!

2015_0228eng0021 by nitram2010, on Flickr

Next will try lapping in seats
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Offline Restoration Fan

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Re: 1978 CB750 K8 project
« Reply #20 on: March 01, 2015, 03:05:42 AM »
Martin, you have some serious skill!  Looks great so far.

Regarding the thick rubber rim tape, that must be a US standard because my rear rim has the same kind.  And i have no idea what that holder on the inner, black half of the rear fender is for.  There was no such holder on mine.

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Stella - Logan's Senior Project    78 750K http://forums.sohc4.net/index.php?topic=141761.0

Logan's Reward - CB500 and CB550 Cafes    http://forums.sohc4.net/index.php/topic,147787.0.html

Offline oldhatt45

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Re: 1978 CB750 K8 project
« Reply #21 on: March 01, 2015, 05:44:22 AM »
Martin,

You've really done a lot and it's looking Good!!!!

As far as that bracket goes, (and this is only guessing) it looks like some kind of electronics mounting box.
And, from your other pictures, it looks like it did fit under the seat so it could not have been very big whatever it was.
The rolled over ends kind of look like whatever was in there slides in from the left side and latches shut?????

Could it have been maybe something like the replacement electronic switch unit (M Unit thing?) ???
Or maybe an electronic ignition unit???

Can you get a better picture (not as dark) of that bracket, maybe top and sides????

I'm inclined to believe that it might have been something off a Police Bike?????

Really nice job so far. 

Charlie
« Last Edit: March 01, 2015, 05:49:49 AM by oldhatt45 »
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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #22 on: March 05, 2015, 09:48:49 AM »
Thanks Charlie

I have removed the bracket, but was curious about its purpose and wondered if it was a standard US item.

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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #23 on: March 05, 2015, 10:31:56 AM »
Valve seats need refacing and 4 of valves have worn stem tops.

Unfortunately K8 has different collet fitting as I have some spare ealier ones.

2015_0301eng0003 by nitram2010, on Flickr

2015_0301eng0008 by nitram2010, on Flickr

Also found that my Neway valve seat cutter pilot set does not go down to 6.5 mm guide.

Tried to get 6.5mm expanding collet which should fit my existing pilot in UK but not available.

Found co. in US that has them at $13 but shipping to UK would be $66  :o

The part only weighs few grams!

http://www.cylinderheadsupply.com/prc165-2.html

http://ep.yimg.com/ay/yhst-58082516732612/neway-expandable-pilot-collet-6-5mm-3.gif

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Offline martin_uk

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Re: 1978 CB750 K8 project
« Reply #24 on: March 11, 2015, 10:21:09 AM »
Finished cleaning up the head and found a nasty surprise in exhaust ports :'(

2015_0311eng0007 by nitram2010, on Flickr

2015_0311eng0008 by nitram2010, on Flickr

Very deep pitting, Im guessing caused by resting water over a long period of storage?

The head on K8 has F type exhaust fitting, but is not marked like a F1 with 392 cast mark,  but has K8 hand stamped.

2015_0311eng0009 by nitram2010, on Flickr

2015_0311eng0011 by nitram2010, on Flickr

Looks like I need to find another K8 or F1 head, as its going to be alot of work to weld up unless anyone knows of a fix to seal pitting and can cope with heat?
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