Author Topic: Slow but steady '78 cb750 rebuild  (Read 9649 times)

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Offline diminished

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Slow but steady '78 cb750 rebuild
« on: September 22, 2011, 11:59:06 PM »
So awhile back I picked up a 1978 CB750 from some kid up in the mountains for $1200 bucks, he had gotten a DUI and had to sell his toys to pay for courts/lawyers/etc and this was the first of them to go. Ive been a fan of the cafe stuff for years, and now that I'm in a house with a garage and have a good steady job I figured its time to start a project. Its amazing how fast tear down goes, and I know that I didn't get as many pictures as I should have, so expect lots of "what the hell am I looking at now" type posts, haha. Since this is my first tear down/rebuild of anything larger than a lawn mower, so I'm taking my time and trying to document everything.

to kick things off i spent a butt ton of money at cycle x. they bored out my jugs to 849cc, and are doing a port job as we speak. they are shaving my crank down to their "pork chop" which lightens it ~7 pounds. new APE studs, new valve springs, titanium retainers, C2 racing cam, heavy duty cam chain, over-sized valves, they're pressing in new guides, cycle X rods, whole new gasket set, new cam chain, new primary chains, they coated my new pistons with a heat barrier/skirting, rocker arms and shafts coated with the same good stuff, spin on oil adapter w/adapters for an oil cooler, electric ignition, and high voltage coils.

next shipment is going to be their 4-2-1 race exhaust, a set of mikuni rs 34mm, and a frame splice kit (since no one here will make the gordon kit anymore. i tried contacting voxonda and he got back to me once, 3 months ago, no word since).

when i get the head back ill be going down to Performance Coatings to have my head, jugs, and valve cover sprayed with a thermal dispersant.

lower cases and frame will get powder once i decide on a color scheme, and i'm going to have to twist brandEn's to find out who did his gorgeous paint and seat.

in the interest of making this a looker, i picked up a bunch of the joker CNC stuff, the alternator cover, the clutch cover, the starter cover, the points cover and the gas cap.

just took delivery of a benjie's whale tank w/knee cutouts. Going to take the stock seat pan and cut it up till it looks good, add a bump out and hide electrics in there.

i picked up a gsxr 600 front end, and this weekend im going to grind the welds off the stock stem, press it out, and follow industrial cafe's lead and swap out the front end on this beast for something a bit more modern. only difference is ill be either using a set of ducati sport classic wheels, or the tubeless alpina's. wanted to have something with a bit more rigidity and larger contact patch then the harley narrow glide stuff, but want to keep the spoke look.

ive got one of carpy's dresda style boxed swingarms coming, and will be modifying it a bit to accommodate a rear caliper.

i would like to run an m-unit from spiegler, if anyone has any experience with them good or bad chime in. i'd love to hear it.

i think that about covers my plans, now lets look at some pictures:
the kid i bought it from had "cafe'd" it, but to him that mean flattening out the seat, pulling out the air box to put pods on, and slapping a set of clubmans on her. its a shame, but this is the earliest photo i have. got so excited to tear her down i forgot to document her humble beginnings.


im definitely not the first one to tear into this engine, and i found all sorts of fun stuff inside, dead moths, a bunch of metal shavings, the retainer spring for the kickstart pawl broken in two, weird stuff. luckily the top end looked pretty good to start with:


original studs, couple of them were stripped on top but they all came out. pistons look like we've been running rich for awhile:


pre-porting:



time for the fun, the lower half. she was leaking oil in a couple of spots that whoever rebuilt it originally screwed up the liquid gasket, but she was all there. pretty clean for the most part, considering the metal shavings/other possible grenade sh|t that was in that lower case.


on transmission, second gear from the left, there is a thin indent in the cent of the gear. is that normal/stock? time to replace it? also ive heard rumors that there is someone out there making a billet clutch basket, and mine has seen better days. anyone know who makes that, and what kind of cost?


this shifter arm has a bit of wear toward the end of its arm. should i replace that bad boy or is that cool? (ignore the metal shavings there, had two stuck screws i had to drill the heads off of and twist out.)


and this was something i just wasnt sure about. to tell the truth i didnt see it until i slapped the empty cases back together and on the bike to get an idea of which mounting brackets i wanted to keep and what i wanted to shave off. in the hole where the transmission came out of i spied a bit of a rough edge to the metal. it looks like there once was something there and it either broke out or was removed. any thoughts?


side note: ive got parts that ill be selling if anyone is interested. make me an offer and if its reasonable there yours. much rather dudes here get these parts then ebay them. will expand this list as im ready to sell more.
front master cylinder, front caliper, mounting bracket. prefer to sell as a package
front forks
rear wheel with sprocket and drum brake insert
front wheel with rotor
original alternator, starter, and clutch covers. a bit dented but ill give them to you for the cost of shipping. seriously.
front headlight ears w/original turn signals
rear turn signals

Offline toytuff

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Re: Slow but steady '78 cb750 rebuild
« Reply #1 on: September 23, 2011, 07:29:08 AM »
Well I'll take those covers off your hands please.  8)

tt

(original alternator, starter, and clutch covers. a bit dented but ill give them to you for the cost of shipping)
« Last Edit: September 23, 2011, 07:32:00 AM by toytuff »

Offline diminished

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Re: Slow but steady '78 cb750 rebuild
« Reply #2 on: September 23, 2011, 10:53:21 AM »
PM me with yer address details and Ill package them up, find out how much shipping will be and get you my paypal info.

Offline liPPy

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Re: Slow but steady '78 cb750 rebuild
« Reply #3 on: September 23, 2011, 02:06:34 PM »
You're not cutting any corners on the spending front are you? lol!

I'll take the front brake assembly off your hands. I'll pm you my details.

Offline diminished

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Re: Slow but steady '78 cb750 rebuild
« Reply #4 on: September 23, 2011, 03:27:20 PM »
ive been saving and planning this for almost 3 years. i've got a vision in my head and 3 years worth of scrimping to blow. i dont have many toys, and ive never had a nice bike. its time to kill two birds with one stone, and i'd say i deserve it, haha.

Offline brandEn

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Re: Slow but steady '78 cb750 rebuild
« Reply #5 on: September 23, 2011, 04:30:55 PM »
Glad to see you decided to start a build thread. Larry Pearson located in Spokane did the paint on my bike. He is a great guy and is passionate about vintage bikes. Check him out at www.meticulouspaint.com . He will set ya straight. As for the seat. I made my seatpan and had Ginger at http://newchurchmoto.blogspot.com/ upholster it. She is in Portland. tweakin used Macs in ballard http://www.mactops.com/ and they are very good too. If you need any powdercoating done pm me and I will give you the number to "my guy" that works for cash under the table out of a storage unit. Shady but does good work....

Your build is off to a good start and a build thread is a great way to get help, suggestions, ideas, and feedback. Let me know if you need any help! Whats your plan for a tail and wheels? Yours is a CB750 K right?
« Last Edit: September 23, 2011, 04:34:15 PM by brandEn »

Offline lucky

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Re: Slow but steady '78 cb750 rebuild
« Reply #6 on: September 23, 2011, 05:10:45 PM »
Those are called shifting FORKS.

Offline liPPy

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Re: Slow but steady '78 cb750 rebuild
« Reply #7 on: September 23, 2011, 08:31:57 PM »
ive been saving and planning this for almost 3 years. i've got a vision in my head and 3 years worth of scrimping to blow. i dont have many toys, and ive never had a nice bike. its time to kill two birds with one stone, and i'd say i deserve it, haha.

Good for you! I'm also rebuilding a k8 so am watching with interest. Subbed :)

Offline diminished

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Re: Slow but steady '78 cb750 rebuild
« Reply #8 on: September 23, 2011, 11:57:20 PM »
@brandEn - mucho gracias! yep yep, rolling a K8. i had bookmarked the new church moto site when they had their own hosting and its migrated to a blog so i was lost in the wilderness. were always looking for reasons to head down to PDX and that sounds like a tailor made excuse, haha. i will be doing a good amount of powder coating, and if you can save me some bucks ive got a beer with your name on it man. as long as i can get a pretty good selection of colors ill be a happy little camper. as far as a tail goes, im still searching. i was planning on keeping the bike two up, but my wife has since purchased her own bike and now has the "bug", so its not as critical. ill prob end up fabricating something myself using the stock seat pan as a base. for wheels im thinking either a set of the ducati sport classic spoked wheels or go big bucks and do a set of the alpina tube less spoked wheels. depends on how much $$ i have left, haha.

@lucky - thx dude! im one of those dudes that can describe things but can't think of the correct word at times. gentle reminders help to sink the knowledge in!

@liPPy - k8s are the way to go man!

so i was feeling a bit froggy and stopped by my brother in laws tonight with the lower triple and we had a go at pressing that thing out of there. started out with a piece of aluminum round stock that we chucked up in his lathe and turned a little nipple onto to fit inside the ID of the stem. we hit the triple with a bit o' heat and applied pressure but the aluminum mushroomed almost immediately.


plan B: we grabbed a piece of steel round stock, chucked it up, turned a nipple, hit it with some heat, and pressed away. one loud pop (prob still a small bit of weld bead breaking) the stem pressed out as smooth as can be, no galling to it at all. happened so fast i wasnt even able to grab an action shot! haha.


and none too soon, because i had a package waiting for me when i got home. my GSXR 600 front end. holy sh|t this is getting fun.

Offline babyfood1217

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Re: Slow but steady '78 cb750 rebuild
« Reply #9 on: September 24, 2011, 12:22:49 AM »
I excited to see your progress, especially with the modern front.  I'm in Ballard if you ever want an extra set of hands to help wrench.
I need help moving my project bike from Wisconsin to Seattle, WA.  Willing to pay well.  Contact if interested.

SOHC member: #438

Project: 1976 CB750K
GSXR forks, Monoshock Rear end, 836 in progress, RC51 pipes, custom frame and everything else.

Offline GRock

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Re: Slow but steady '78 cb750 rebuild
« Reply #10 on: September 24, 2011, 07:25:25 AM »
ive been saving and planning this for almost 3 years. i've got a vision in my head and 3 years worth of scrimping to blow. i dont have many toys, and ive never had a nice bike. its time to kill two birds with one stone, and i'd say i deserve it, haha.

Good for you! I'm also rebuilding a k8 so am watching with interest. Subbed :)

+1  You say "slow but steady" but it looks like you moving along pretty fast! I just split my cases last night and I've had my K8 scense Aprill 2010. I'll be following along with interest!

Offline brandEn

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Re: Slow but steady '78 cb750 rebuild
« Reply #11 on: September 24, 2011, 08:45:49 AM »
Right on! Ducati Sport Classic wheels, what a GREAT idea. If you can find a set I would make it happen. Those wheels would look amazing. GSXR frond end and a boxed swing arm...man your off to a great start.

Offline diminished

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Re: Slow but steady '78 cb750 rebuild
« Reply #12 on: September 24, 2011, 09:27:31 AM »
@babyfood1217 - thanks man! i may take you up on that offer once i start reassembly! i freaking love the bike culture we have here in seattle, even with the rain, haha

@GRock - hehe, ive had this bike since summer 2008. rode it the way i bought it and saved my clams for the last three years. and the tear down happened about a month ago, i just got around to posting a build thread.

@brandEn - that was actually a rob idea, but im thinking im going to run with it. ive got a line on a set off a '08 bike for 900 with rotors, but im leaning more toward the alpina's. more than double the cost, but tubeless, and they look fvcking hot. still waiting on that carpy swing arm, ordered ~a month ago.

Offline GRock

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Re: Slow but steady '78 cb750 rebuild
« Reply #13 on: September 24, 2011, 04:21:46 PM »
It's been my experience that Carpy is hit or miss when it comes to customer service. Good Luck.

Offline tweakin

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Re: Slow but steady '78 cb750 rebuild
« Reply #14 on: September 24, 2011, 07:15:10 PM »
Nice!  Great to see another 750 getting some love in my area.  You have a great plan, just take your time and follow your vision.

Offline diminished

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Re: Slow but steady '78 cb750 rebuild
« Reply #15 on: September 25, 2011, 08:46:57 PM »
slapped the empty cases back together, tossed it back on the frame to start getting ideas of what i can trim off the frame, slapped the tank and the POs seat on there. starting to get some ideas for the seat, paint.


this little bit of pretty came in the mail for me yesterday:

a sweet little ebay score, a roland sands design top triple. originally meant for gsxr1000, she looks too pretty on top of that set up.

so after pressing out the cb750s stem i measured both it and the gsxr600s, and they are the same length. the gsxr600's has different widths, but now im thinking i might mic that bad boy up, call all balls, and see what if they either have a tapered set of stem beatings that will fit, or can put one together for me and use the gsxr's stem. thoughts?

Offline lucky

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Re: Slow but steady '78 cb750 rebuild
« Reply #16 on: September 28, 2011, 05:32:25 PM »
It's been my experience that Carpy is hit or miss when it comes to customer service. Good Luck.

Scorpio stuff. He is just busy with all that stuff he has to take care of.

Offline diminished

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Re: Slow but steady '78 cb750 rebuild
« Reply #17 on: September 29, 2011, 02:05:33 PM »
@lucky - scorpio stuff? you talking about his star sign or a manufacturer?

finally got the gsxr front end taken apart and took the lower triple/stem over to my brother in-laws. using info gotten from the dudes here we set up the press to push the stem out the bottom end of the triple as we thought that there was either a circlip or a wire 5mm from the bottom of the stem (more on that later).


there was way to much flex in that stem though, and even after hitting the triple with some fire it didnt want to come out.


figured that we could accomplish the same thing but without the cantilevered effect of the contact points of the triple being offset  from the line of the stem if flipped that bad boy upside down and pushed the triple off the stem instead of the other way around. Found a piece of piping that fit around the stem that we could use to put direct pressure on the triple and hit it with some fire again. one loud pop and that bad boy slowly came off. mic-ing it later we found there was a  taper, and the original pop wasn't the wire/circlip, but a lip that had been machined into the stem. not sure when that changed but this front end is off a 09 model.


stems are almost identical length, and after calling all-balls they told me that they do not have a set of bearings that the ID would fit around the stem of the GSXR and the OD would fit into the frame of the cb750. note the huge lip on the end of the GSXR stem:


next we thought we would use the bottom of the GSXR stem as a bushing, hollowing out the ID for a zero tolerance fit with the OD of the cb750 stem. im guessing thats not going to work as their just too close in size.
thick end of the taper on the GSXR stem:


constant OD for the cb750 stem at the bottom:


im guessing thats why industrial cafe heated up his cb750 stem and pounded a taper into it, and it looks like im going to follow suit.

Offline babyfood1217

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Re: Slow but steady '78 cb750 rebuild
« Reply #18 on: October 01, 2011, 10:15:33 AM »
I would call ALL-BALLS again.  I got a set or bearing that did exactly what you are trying to do.  If they can't find it, I recommend heading down to your local bearing shop (I used to frequent a place called Motion Industries) and see what they can find. 

If all my bike stuff weren't 2000 miles away, I'd run and check numbers.  I'll see if someone back home can scour around for the packaging...
« Last Edit: October 01, 2011, 11:14:02 AM by babyfood1217 »
I need help moving my project bike from Wisconsin to Seattle, WA.  Willing to pay well.  Contact if interested.

SOHC member: #438

Project: 1976 CB750K
GSXR forks, Monoshock Rear end, 836 in progress, RC51 pipes, custom frame and everything else.

Offline diminished

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Re: Slow but steady '78 cb750 rebuild
« Reply #19 on: October 06, 2011, 04:43:06 PM »
talking to the all-balls dudes again, they said they used to have a custom bearing that was the bearings of one set combined with races of another that would work for this swap, but they had some problems with the bearings failing. sounds like im going to be using my original stem.

Offline babyfood1217

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Re: Slow but steady '78 cb750 rebuild
« Reply #20 on: October 06, 2011, 06:33:28 PM »
...but they had some problems with the bearings failing...

Yikes, never heard about that.  I'll try to get in touch with someone back in Wisconsin who can check and see what I've got in place in the mean time.  Good luck!

-Chris
I need help moving my project bike from Wisconsin to Seattle, WA.  Willing to pay well.  Contact if interested.

SOHC member: #438

Project: 1976 CB750K
GSXR forks, Monoshock Rear end, 836 in progress, RC51 pipes, custom frame and everything else.

Offline articblue

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Re: Slow but steady '78 cb750 rebuild
« Reply #21 on: October 06, 2011, 06:48:58 PM »
great so far, looking forward to updates and some great ideas
Eventually I'll get something that runs, but until then I'll wrench until I make it run.
Project 750

Also, another 'new' project 1975 Honda CB400F.

Offline diminished

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Re: Slow but steady '78 cb750 rebuild
« Reply #22 on: October 07, 2011, 02:17:13 PM »
talked to a local machine shop today and it sounds like there is enough material on the gsxr stem to mill it down to match the cb stem. going to give that a go and hope for the best.

Offline diminished

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Re: Slow but steady '78 cb750 rebuild
« Reply #23 on: October 11, 2011, 02:31:51 PM »
lower cases are out being bead blasted, gsxr stem is being machined down to fit the cb750 bearings, thinking about color combos, and starting thinking about glyptal. anyone have experience with it? a couple of dudes here and my local mechanic swear by it, but im not 100% sure. in the product specs it says its good for a max of 250 degrees fahrenheit. i'd guess that it gets a bit above that in the cases, especially when really getting on it with all the upgrades. anyone have experience with it? hear of it failing? have to pick pick flakes out of your oil? let me know.

Offline brandEn

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Re: Slow but steady '78 cb750 rebuild
« Reply #24 on: October 11, 2011, 06:51:48 PM »
Check out my buddys build. He is using Glyptyal as well as a bunch of others
http://forums.sohc4.net/index.php?topic=87377.0