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Author Topic: '78 CB750K Cafe Build - Money Pit!  (Read 23443 times)

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Offline callmejarob

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'78 CB750K Cafe Build - Money Pit!
« on: November 30, 2014, 09:24:23 AM »
Well I started a build thread on DoTheTon as well but I frequent this site more so it is time I introduce myself!

My name is Jarob and this will be my second build.  The first was a piece of crap 1974 CB360 that I half assed and rode around for a year before selling it off.  This project will be my first "real" project as I am rebuilding everything if it needs it or not.  I want this bike to last me the next 100,000 miles without worry.

The bike is a 1978 Honda CB750K I picked up off craigslist with 18,XXX miles on it.  Snagged it for $1200 including stand, dyna2000 ignition, carpy exhaust, and recent fork rebuild and new rear shocks.  She was running great and i enjoyed her for several months before winter came and I tore it down to every last screw.

Currently the engine is completely apart and has been soaking in diesel fuel.  The cylinder jugs, head, covers, and carbs are being sent off to get vapor blasted this week which I am very excited about.  The case will be soda blasted by me and then painted as close to stock Honda engine silver as possible.  The engine will be bored 0.5 (2nd) over with new pistons, new HD studs, all new chains and guides/tensioners (top and bottom), new gaskets, etc.. The previous owner already installed an aftermarket cam. 

I was originally going to use a BCR tank/seat but said FUK that after a little research.  I am now outsourcing to a local shop here in DFW, Retro Moto, to create me a one off tank/seat combo in aluminum.  The frame will be painted black, engine will remain aluminum finish with copper accents, and the tank/seat will be light gray pearl with brown stripes.

ALL electronics will be MotoGadget.

Here are the pictures I have up to now.  I will update this project as I work on it over the weekends.



















I was amazed that it fit in the back of my Abarth!!





Stay tuned!
« Last Edit: April 06, 2015, 07:42:27 AM by callmejarob »
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Offline SOHC4 Cafe Racer Fan

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Re: '78 CB750K Cafe Build
« Reply #1 on: November 30, 2014, 10:50:48 AM »
Nice Magnum PI era Ferrari!
Why paint the motor if you have it blown apart versus powdercoating it?
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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 callmejarob

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Re: '78 CB750K Cafe Build
« Reply #2 on: November 30, 2014, 03:03:51 PM »
Im only painting the cases, the top half of the engine will be bare aluminum from the vapor blasting.
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #3 on: December 01, 2014, 10:12:09 AM »
Quote from: calj737 on November 30, 2014, 04:16:50 PM
Vapor blasting is a beautiful finish, but it will oxidize after some time. Might consider having a clear powder coat applied over it to retain the beauty of it. Plus, powder cost over it will protect it from fuel and oil stains.

Ditto on the 328!

Good to know thank you!

So now I am thinking about just having the whole engine powder coated in an aluminum finish after a good soda blast.  Thoughts?
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Offline SOHC4 Cafe Racer Fan

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Re: '78 CB750K Cafe Build
« Reply #4 on: December 01, 2014, 10:47:29 AM »
Quote from: callmejarob on December 01, 2014, 10:12:09 AM
Quote from: calj737 on November 30, 2014, 04:16:50 PM
Vapor blasting is a beautiful finish, but it will oxidize after some time. Might consider having a clear powder coat applied over it to retain the beauty of it. Plus, powder cost over it will protect it from fuel and oil stains.

Ditto on the 328!

Good to know thank you!

So now I am thinking about just having the whole engine powder coated in an aluminum finish after a good soda blast.  Thoughts?

Powdercoating the entire motor one color (aluminum) might be a little boring.  You may want to off-set it with a second color (even black).  There are a bunch of color options to choose from.  Make it unique and yours (and hopefully tasteful).
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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 callmejarob

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Re: '78 CB750K Cafe Build
« Reply #5 on: December 01, 2014, 10:53:29 AM »
I want the motor to look like its just a completely stock aluminum engine, not interested in any black or other colors.  I will be getting a few accents on it plated in copper, but there will be enough going on on the bike as a whole.

Oh and thanks for the comments on the Ferrari!  Its a 1979 308 GTS, personally for the price I don't think you can beat it!
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Offline SOHC4 Cafe Racer Fan

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Re: '78 CB750K Cafe Build
« Reply #6 on: December 01, 2014, 11:12:21 AM »
Quote from: callmejarob on December 01, 2014, 10:53:29 AM
I want the motor to look like its just a completely stock aluminum engine, not interested in any black or other colors.  I will be getting a few accents on it plated in copper, but there will be enough going on on the bike as a whole.

Oh and thanks for the comments on the Ferrari!  Its a 1979 308 GTS, personally for the price I don't think you can beat it!

I guess I assumed because you were building a custom café that the motor would also follow the custom route.  Since you want the motor to appear stock, then I'd recommend going with aluminum PC.  There are several shades available to match a NOS aluminum. 

The 308 GTS is an affordable exotic.  Not as persnickety about service as others, and has classic lines.  The 79 was the year used for the first season of Magnum.  Although some earlier years were made with fiberglass bodywork, the steel doesn't add too much weight (26 lbs additional) and is infinitely more durable.  Awesome supercar!
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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 callmejarob

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Re: '78 CB750K Cafe Build
« Reply #7 on: December 01, 2014, 01:36:50 PM »
Can I soda blast the head with the bronze valve guides still in there?  Sorry if this is a dumb question!
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #8 on: December 01, 2014, 03:41:10 PM »
Also, second guessing if I want to bore.  The cylinders are in GREAT shape but what are your thoughts on my pistons?  It looks to be some pitting on them.





Is this piston fine?
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #9 on: December 01, 2014, 05:34:23 PM »
Thanks for the info, and yea I plan on having it measured but was wondering if the pitting or scratches were too severe.
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #10 on: December 01, 2014, 05:50:25 PM »
Alright I just double checked my cylinders and they are in great shape.  very smooth and actually look to be recently honed.

This is piston #3 and by far the worst condition of the 4.  Is this still useable?  When running my fingernail across those scratches I can feel them but it doesn't "catch" in them.

Any advice is greatly appreciated!





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Offline martin99

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Re: '78 CB750K Cafe Build
« Reply #11 on: December 02, 2014, 01:41:50 AM »
I think Cal already answered this. If there is wear on the piston skirt, there will be corresponding, although not an equal amount, of wear on the bore. You simply can't eyeball this and the bores need to be measured properly for wear and taper. Likewise pistons and ring gaps. If they are in spec, then it's your call as to whether to re-use those pistons, they look borderline to me. I've re-used pistons in a similar condition before when financial restraints didn't allow replacement, but it's not ideal.
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Build threads:
77 750F2 Refresh Project http://forums.sohc4.net/index.php?topic=144075.0
TRIBSA http://forums.sohc4.net/index.php/topic,160296.0.html

1977 CB750 F2
1958 Norton Model 99
2011 Triumph Street Triple 675

Offline Restoration Fan

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Re: '78 CB750K Cafe Build
« Reply #12 on: December 02, 2014, 04:22:02 AM »
Quote from: calj737 on December 02, 2014, 04:08:18 AM
Calipers are used at several locations on the bore and the piston to indicate circularity and taper (bore). If the piston skirt has that kind of galling, the bore probably has as well. How about some clean pictures of the cylinders too?

If the pistons measure in spec, I'd at least get new rings and have the cylinders honed. This will give you the best fit and compression going forward. I'll add, I also like to have the skirts coated with Dry Film Lubricant professionally. It reduces friction, heat, and prolongs life of the piston and bore. Runs about $15/piston. Here's a picture of some 550 pistons I am reusing and did exactly this. Plus had the domes shot with a thermal reflective coating, and undersides with an oil shed coating for added fun.

Holy cow, cal, that piston looks beautiful.  Where do you get the Dry Film Lubricant done?  (By the way, does anyone else think that Dry and Lubricant in the same description seems like an oxymoron?  :D)
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Ron

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 callmejarob

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Re: '78 CB750K Cafe Build
« Reply #13 on: December 02, 2014, 06:02:12 AM »
Thats fantastic cal!  Ive already planned on replacing the rings and honing the cylinders. 

The whole reason I'm confused is because how clean the cylinder is for that number 3 piston, its literally perfect.  Ill get them measured today or tomorrow and report my findings back here.  Thanks for the help guys!
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #14 on: December 03, 2014, 11:48:13 AM »
Alright!

Cal, thank you for your help/suggestions.

I had the cylinders measured at a local motorcycle performance shop and they are in spec.  He also said my pistons look fine. 

Now, I will hone the cylinders myself.  Do I need to have them measured again after the hone or am I fine as long as I dont go overboard?  I will be following the My CB750 book. 

And some other good news, I found a shop to dry film lubricate my pistons for me.  $20 a pop but Ill get it done since I only need a hone anyways.
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #15 on: December 03, 2014, 06:07:01 PM »
Haha yes it is..

Im still driving myself crazy with how I want to treat my engine...  Im tossing up the idea of vapor blasting again.  Since I saved money on the bore/pistons maybe I should just say F it and get everything vapor blasted AND powder clear coat.  One and done.

Thoughts?
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Offline AintNoEasyWay

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Re: '78 CB750K Cafe Build
« Reply #16 on: December 04, 2014, 11:51:15 AM »
I'm in. Looks great so far.
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #17 on: December 06, 2014, 08:32:50 PM »
Various parts and pieces coming in the mail this week including this little gem that came in from cyber monday specials.



MotoGadget M-Unit v2!  I don't know if I mentioned but this build is going full blown MotoGadget.
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Offline Prez1967

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Re: '78 CB750K Cafe Build
« Reply #18 on: December 07, 2014, 06:27:09 AM »
Following with much interest as I'm eventually going to rebuild my '78 as well! Looking forward to progress on this build :thumbsup:
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #19 on: December 07, 2014, 07:22:08 AM »
Quote from: calj737 on December 07, 2014, 02:32:56 AM
I sure hope you got their M-Key and opted for the M-Button too....? If you use the M-Button, you'll need resistor wires on your coils else you'll get interference and irregular behavior from the Button.


Im ordering their parts little by little but yes those two are on the list.  Good to know about the resistor.
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #20 on: December 12, 2014, 07:37:51 AM »
Haven't made any progress this last week or two but I did buy a soda blaster and ordered a bunch more parts online.  My sandpaper kit should be here and I'll get to polishing this weekend and next week the engine will be blasted finally and I can begin the rebuild.

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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #21 on: December 14, 2014, 06:51:49 PM »
Decided I do not like polishing very much.  I am not a fan of mirror finishes so they will be left like this.  Went from 180 to 2000 grit wet.



Having some fun in a new car,


and my favorite beer of all time (not at the same time as the car!)
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #22 on: December 23, 2014, 07:21:18 PM »
Still just polishing parts and working a lot.  Hoping to get the cases painted the day after christmas, if not it won't be until the new year..!
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #23 on: December 31, 2014, 05:39:48 PM »
Haven't had much time to work on the project with the holidays but I did knock out a little bit today.

More polishing:





Bought myself a soda blaster for christmas and blasted the engine cases, pistons, exhaust, and jugs today.  Was hoping to paint them too but being 30 degrees out it was just too cold without an indoor studio.









Loaded it all back into the Abarth ready for paint.




Hopefully Ill paint within the following week and I can begin reassembly of the engine.  The frame still needs to be modified and sent off to powder coating and I am waiting on my custom gas tank to be made so no hurry.

Happy New Year!
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Offline callmejarob

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Re: '78 CB750K Cafe Build
« Reply #24 on: January 08, 2015, 06:52:02 AM »
Made some progress this past week!

Set up a "paint booth" at my work and painted the engine. 

The process went: De-greased, soda blasted, washed, acetone neutralized, blow dried, primed, sanded, wiped, painted 3 coats, cured with a heat gun, 4 days later two oven cures.  Looks good and is hard as a rock!  I used Duplicolor primer and engine enamel.




















My pistons are at the shop getting "dry film lubricant" coated and I just ordered a 2.5" 320grit flex hone which should be here this week.  Once that arrives I will begin reassembly of the engine!

Also, does anyone ever replace the radial bearings in the transmission?  I left mine in and they got a little gunked up when I was washing the engine.  Do I NEED to replace them now or can I just lube them up nice and good and get them rolling good again?

Thanks!
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