Author Topic: My CB750 Love Affair  (Read 2623 times)

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Offline Coyote13

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My CB750 Love Affair
« on: August 13, 2014, 10:48:42 AM »
Howdy gents! Been quite a while since I frequented this forum, but glad to be back with you guys.  Posted this on DTT already, thought this would be a more appreciative crowd for my purposes...

The Story

This month marks the 5th anniversary of the delivery of my 1978 CB750K.  I loved the bike the moment I saw it, and knew I had to have it.  I bought it off of eBay, for a price both I and the seller could live with, and had it shipped from Kentucky to Texas essentially sight unseen, other than the photos in the listing.  It was delivered using Uship, and arrived in the back of a long panel van, stuffed in between a couple of old scooters and some other miscellany.  The moment I fired it up, I knew I was in love.  The SOUND, my god!  It needed new control cables all around, though not immediately, and it took a throttle cable snapping a few weeks later to bring me around to replacing all of the cables.  As a matter of course, I pulled and cleaned the carb bank, which I rejetted for the pod filters that the PO had slapped on.  I considered changing them out to a stock unit or other, but instead did my homework on carb theory, function, and tuning, and tuned it as close to perfect as I could.  The pods would stay, for the time being. They DO look pretty cool.  I noticed the chain was a little rusty, and the sprockets worn, so I picked up a nice little 530 chain and sprocket set, a new rear tire which was desperately needed, and an oil and filter change.  I rode it just like that for the rest of the summer, and most of the winter, when eventually a coil died on me.  Always one to upgrade rather than replace, I picked up a Dyna S and some Dyna coils, new plugs and wires, and went to town.  Once I had it timed, I had never seen it idle and run SOOOO smooth.  Another oil change later and I was riding another season. 

Now mind you, this is all while I'm still in college, on a college kid's budget, bartending for extra cash and lacking much in extra time.  So when I started to notice a little bit of the "normal" CB head gasket leak, I paid it little mind and rode my beloved 750 as she was meant to be ridden.....hard.  Fast forward a couple of years, graduated college, got a real job, bought a house with a garage, a couple motos have come and gone, a few girlfriends as well, and the CB remains, with really only minor changes.  She's been through a few tail lights, went from a 4-2 to a 4-1, Progressive rear shocks, stainless braided brake lines all around, and tossed out the pods in favor of a breadbox from Steel Dragon.  I won't say she's in the best shape of her life, but she has taken my abuse in stride and has never let me down.  Yet....that pesky head gasket.  It has gotten slowly and progressively worse over a few seasons of riding, to the point that I feel guilty whenever I walk out to the garage.  So, last night, I put my foot down and said ....NO MORE!  Something must be done!  But, as I mentioned earlier, I'm not one to just replace. My bucket list for this bike began the minute I bought it.  And so begins my adventure....

The Plan

Since most of my supporting items are either new, or in good shape, I am going to be focusing on engine performance, as well as some cosmetic upgrades.  Wish list items are up for debate as to brand, vendor, etc., but this is the general outlook for the future of my first moto. If any of you guys have suggestions based on experience, feel free to chime in.

•836 Kit, APE, Dynoman, etc. (just pulled the trigger on the eBay 836, so I can put a little extra cash into the head)
•Web 41a or 63a
•Headwork by Mike Rieck
•HD cam chain and studs
•New seat and a toolbag to match
•Paint spokes and hubs
•Blast/paint/polish engine and covers
•Possibly paint frame and other small bits
•Rebuild front end, including steering bearings

Disclaimer:  I have never done a full rebuild before and I have never done a big bore before.  I have a good working knowledge from years of research and reading, but I lack hands on experience and I'm certain I will have questions. 

And here's she is, as she sits today.  Not a great picture, but there will be more....
« Last Edit: August 13, 2014, 06:26:27 PM by CoyoteUSP »
'78 CB750K.  Throttle ripper.
'71 CB100.  Grocery getter.
'01 XL883.  Panty dropper. Gone but not forgotten.

Offline 70CB750

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Re: My CB750 Love Affair
« Reply #1 on: August 13, 2014, 11:07:04 AM »
Subscribed  :)
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I love it when parts come together.

Dorothy - my CB750
CB750K3F - The Red
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2006 KLR650

Offline SOHC4 Cafe Racer Fan

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Re: My CB750 Love Affair
« Reply #2 on: August 13, 2014, 02:04:21 PM »
Coyote,

Good lucking Kate (K8).  If you are splitting the cases, you should check out the lower end components (transmission, crank, bearings, etc.), and changing out the primary chain, too; if you are going to split her open, do it once and do it right.  I would also suggest taking a close look at the cam chain tensioner, and possibly replacing it with a new HD tensioner from Cycle X or (at minimum, swapping out the rubber components with NOS ones).  This was a weak point of the CB750 motors.  Also plan on replacing all seals, pucks, gaskets, etc. with new ones.  Why spend all of the money on a big bore and Mike Rieck head and then cheap out on small parts. 

Make sure to be thorough in your cleaning of any engine parts after blasting to make sure any oil passageways are not blocked.  There are stories of people soaking their engine components in cleaners, air blasting them and still finding media in the parts.  Also, deck the mating surfaces of the cylinders, head and valve covers to ensure they are flat (and not warped) -- one more safeguard to help eliminate leaks.
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 Coyote13

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Re: My CB750 Love Affair
« Reply #3 on: August 13, 2014, 04:55:05 PM »
Thanks CRF, I'll be sure to heed your advice.  I wasn't planning to split the cases, as everything in the bottom end seeeems to be fine (fatal last words, I know).

Does anyone know how far you can go into headwork with the eBay 836?  I just saw mention in another thread that there may be some valve/piston clearance issues if I were to use oversized intake* valves, but I imagine the cam's lift comes into play more so than the actual size of the valve. Thoughts?
« Last Edit: August 13, 2014, 06:27:24 PM by CoyoteUSP »
'78 CB750K.  Throttle ripper.
'71 CB100.  Grocery getter.
'01 XL883.  Panty dropper. Gone but not forgotten.

Offline Stev-o

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Re: My CB750 Love Affair
« Reply #4 on: August 13, 2014, 06:12:11 PM »
Looks like a good plan.   I would add new springs and fork seals to the front end rebuild. 
I recently installed Progressives in my K4. 
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Coyote13

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Re: My CB750 Love Affair
« Reply #5 on: August 13, 2014, 06:15:49 PM »
Looks like a good plan.   I would add new springs and fork seals to the front end rebuild. 
I recently installed Progressives in my K4. 

That's the plan! I've had Progressives in the rear for a few years now and I just love em.  Front probably should have been done at the same time, but the budget said otherwise and I had to put it on the back burner.  This project is gonna be the fulfillment of 5 years of daydreaming.
'78 CB750K.  Throttle ripper.
'71 CB100.  Grocery getter.
'01 XL883.  Panty dropper. Gone but not forgotten.

Offline SOHC4 Cafe Racer Fan

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Re: My CB750 Love Affair
« Reply #6 on: August 13, 2014, 11:07:31 PM »
Thanks CRF, I'll be sure to heed your advice.  I wasn't planning to split the cases, as everything in the bottom end seeeems to be fine (fatal last words, I know).

Does anyone know how far you can go into headwork with the eBay 836?  I just saw mention in another thread that there may be some valve/piston clearance issues if I were to use oversized intake* valves, but I imagine the cam's lift comes into play more so than the actual size of the valve. Thoughts?

Just let Mike know what pistons you plan to use.
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 albertaboy

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Re: My CB750 Love Affair
« Reply #7 on: August 14, 2014, 03:25:34 AM »
Thanks CRF, I'll be sure to heed your advice.  I wasn't planning to split the cases, as everything in the bottom end seeeems to be fine (fatal last words, I know).

Does anyone know how far you can go into headwork with the eBay 836?  I just saw mention in another thread that there may be some valve/piston clearance issues if I were to use oversized intake* valves, but I imagine the cam's lift comes into play more so than the actual size of the valve. Thoughts?

I just had Mike build my head and bore my cylinders for 836 using the ebay seller "cruzinimage_co" 836 piston kit. You definitely can not go large valve with those pistons despite your cam choice. Like already mentioned, Mike will be able explain your options.
1975 CB750K
No where to go and all day to get there.
My build thread: http://forums.sohc4.net/index.php?topic=131424.0

Offline Coyote13

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Re: My CB750 Love Affair
« Reply #8 on: August 14, 2014, 07:48:35 AM »
Awesome, thanks guys.  I know Mike knows his heads and a lot about these bikes generally, but I didn't want to assume how much knowledge he had regarding eBay stuff.  I have no problem letting him guide me through this.
'78 CB750K.  Throttle ripper.
'71 CB100.  Grocery getter.
'01 XL883.  Panty dropper. Gone but not forgotten.

Offline Coyote13

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Re: My CB750 Love Affair
« Reply #9 on: August 18, 2014, 11:34:27 AM »
Went for the 41a hardweld, should be receiving many packages in the next few weeks.  A couple have already shown up and are waiting for me at the post office.  Giggity!!!
'78 CB750K.  Throttle ripper.
'71 CB100.  Grocery getter.
'01 XL883.  Panty dropper. Gone but not forgotten.

Offline Coyote13

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Re: My CB750 Love Affair
« Reply #10 on: August 20, 2014, 12:31:10 PM »
So most of my loot has arrived, and I find myself standing in the living room giggling with glee.  It started with a chuckle and quickly turned to raging, maniacal laughter. Aside from a ballistic battery (installed), new R/R (installed) and a stainless hex bolt set, this is about it.  Got a new home built seat coming in as well, and a slick set of mini gauges from DCC. Now just need to get the motor pulled and torn down to send out the head and cylinders.

Started in on the front end last night and realized I hadn't ordered new oil seal rings (might get away with using the old ones) and dust covers.  So they're torn down, but won't go back together until at least the dust boots get here.

Added a shot of the current state of affairs in case anyone's tracking.
'78 CB750K.  Throttle ripper.
'71 CB100.  Grocery getter.
'01 XL883.  Panty dropper. Gone but not forgotten.

Offline Coyote13

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Re: My CB750 Love Affair
« Reply #11 on: August 21, 2014, 02:49:34 PM »
Ran into my first problem, and I could use some suggestions.  I cannot, for the life of me, get the fork seals out of the lowers.  I have tried:  hot water, boiling water, PB Blaster, WD-40, flatheads, needle nose pliers, blunt nose pliers, and a c-clamp with small block of wood.  The one I'm working on now is about halfway out and will budge no further. 

Should I try to Dremel it??? I see that ending....poorly.
'78 CB750K.  Throttle ripper.
'71 CB100.  Grocery getter.
'01 XL883.  Panty dropper. Gone but not forgotten.

Offline SOHC4 Cafe Racer Fan

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Re: My CB750 Love Affair
« Reply #12 on: August 21, 2014, 03:16:19 PM »
Forgive me for asking, but you did remove the circlip first, right?
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 Coyote13

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Re: My CB750 Love Affair
« Reply #13 on: August 21, 2014, 03:52:28 PM »
It'd be pretty funny if I didn't, wouldn't it?


But yeah, I did.  Thanks for asking!
'78 CB750K.  Throttle ripper.
'71 CB100.  Grocery getter.
'01 XL883.  Panty dropper. Gone but not forgotten.

Offline calj737

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Re: My CB750 Love Affair
« Reply #14 on: August 21, 2014, 04:47:03 PM »
Drill a small pilot hole in it, then use a wood screw screwed in, pull with hammer claw.
'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline SOHC4 Cafe Racer Fan

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Re: My CB750 Love Affair
« Reply #15 on: August 21, 2014, 04:48:37 PM »
Drill a small pilot hole in it, then use a wood screw screwed in, pull with hammer claw.

In other words, finesse it before you rip it out!
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 Stev-o

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Re: My CB750 Love Affair
« Reply #16 on: August 21, 2014, 06:16:22 PM »
I use a real small c clamp, no bock of wood needed if you are careful. Once it moves, it should just pull right out.

Some guys use heat, but I have not needed it.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Coyote13

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Re: My CB750 Love Affair
« Reply #17 on: August 21, 2014, 07:22:27 PM »
Success!  Tried the wood screw and it didn't work out too well, so I clamped down the fork lower and used the claw end of the hammer to pry out the seals. Worked like a charm!
'78 CB750K.  Throttle ripper.
'71 CB100.  Grocery getter.
'01 XL883.  Panty dropper. Gone but not forgotten.

Offline Stev-o

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Re: My CB750 Love Affair
« Reply #18 on: August 21, 2014, 07:24:48 PM »
Good.  Use the old seal to hammer in the new one.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........