Author Topic: "Mouse" - a 1978 CB750K project [PICS]  (Read 14034 times)

0 Members and 1 Guest are viewing this topic.

Offline Phinn

  • Subversive
  • Enthusiast
  • **
  • Posts: 224
"Mouse" - a 1978 CB750K project [PICS]
« on: January 28, 2015, 10:58:23 AM »
This is "Mouse," my 1978 CB750K project. 





Mouse has led a hard life, and is not what I'd call a "survivor."  Nor is it a candidate for stock restoration.  The engine is seized, and there are a few parts that are both (a) important and (b) missing.  But it was practically free (and worth every penny!), and it's mine, so I'll be getting it back on the road in a few weeks.  (Stop laughing.)

The electrical system is non-functional.  I've expertly diagnosed the problem as a "missing power cable" issue. 


There's also the small matter of the ignition switch being packed with sand to the point of, well, not-turning.  A new one is on the way. 

The chain adjuster on the right side is missing the little "key" that HOLDS THE REAR WHEEL ON.


I'm not sure what this hose is supposed to attach to, but it looks important. 


The PO put crash guards on it, but then apparently crashed them, so they are both bent.  But that's not all -- the alternator cover bolts were probably leaking, so he installed longer bolts and inserted little brass sleeves over them to act as a kind of washer-type system, and then cranked the living **#$ out of them.  This backyard mechanic scheme plugged the leaking cover, but because they stick out even when fully inserted, they are susceptible to being bent, which they were.  By the aforementioned crash guards.  And ... then started leaking again. 



The brakes will need a little cleaning. 


I removed the airbox (which is in good condition, actually), and discovered something that gave this project its name -- a rodent nest.  It probably interfered with the air flow.  My 11 year-old son came up with the name.  It fits, I think.


When I removed the carbs, I found a strange problem -- intakes for Nos. 1, 2 and 4 are coated in chalky substance.  I assume that's bad.



The carbs themselves seem to be intact, on the outside, apart from missing two of the little bolts that hold the crass-brace on. 


The carbs don't look that good on the inside, though.


This one has a moisture problem


This one has sand inside.  Also bad, right? 


I now assume the bike was stored at the bottom of the ocean -- the exhaust outlet (especially No. 1) has sand inside.  Sand.  Not crud.  Not carbon.  Not miscellaneous gunk.  I'm using my expert powers of scientific diagnosis and speculate the sand might have something to do with the engine seizing. 


Here's spark plugs 1 through 4.  No. 4 wasn't seated more than about 3 turns.  No. 1 was welded in so tight that it broke my breaker bar.  But, I was victorious in the end.


Getting the transmission cover off proved to be difficult.  The upper-most rear bolt (the long one) didn't want to budge, no matter how many different tactics I threw at it.  I McGuyvered a "tool" to cut a new slot in the head --


I said a few curse words, and maligned the invention of the Phillips head screw/bolt/whatever and its use on motorcycles. But I was victorious in the end. 


This is what I found when I finally got the cover off.


And the sprocket area is a little ... dirty.


So, the next step is to remove the engine, de-gunk-ify it, and get Mouse back on the road. 
« Last Edit: July 26, 2015, 03:21:45 PM by Phinn »
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline dave the welder

  • dave the welder
  • Hot Shot
  • ***
  • Posts: 500
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #1 on: January 28, 2015, 11:06:14 AM »
2 weeks tops and it will LIVE
don't buy it build it

Offline scunny

  • Old Timer
  • ******
  • Posts: 4,618
  • don't call me expert
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #2 on: January 28, 2015, 11:07:57 AM »
enjoy the experience.
past-cb100,ts250,cb500,cb500,gs1000,gs650g.phillips traveller
present-CB 650 retro
            VTR1000F3
           XL250S riverbed rocket
           TS250[sold]
           TS185[sold]
           XL125S[sold]
           MT50 (white)
           MT50 (red)[sold]
           KN250/XS400 project
           XR/XL250 bitsa under construction
           SL100[sold]
           XL250R
           pedal(pub bike) leaks oil
my gallery http://gallery.sohc4.net/members/personal/scunny

Offline SOHC4 Cafe Racer Fan

  • Speak up, Whipper-Snapper! I'm a
  • Really Old Timer ...
  • *******
  • Posts: 15,731
  • SOHC/4 Member #1235
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #3 on: January 28, 2015, 12:07:03 PM »
Sand!? WTF!?  At least the "mouse" took good care of the airbox.

This one is pretty rough -- looks like a ground up rebuild.  Are you simply trying to get it to be a runner, or any design changes during the process. 
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 calj737

  • Really Old Timer ...
  • *******
  • Posts: 21,033
  • I refuse...
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #4 on: January 28, 2015, 12:25:53 PM »
Imagine what the inside of the tank will look like! Perhaps a POs girlfriend or Ex- poured sand into the tank as some vandalism? Might explain the presence of so much sand everywhere.
'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 70CB750

  • Labor omnia vincit improbus.
  • Really Old Timer ...
  • *******
  • Posts: 14,801
  • Northern Virginia
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #5 on: January 28, 2015, 01:53:45 PM »
Subscribed and good luck.

If you mean the relay by ignition switch, it is rebuildable too. 

Honda cross head bolts are JIS, not Philips. It can make a difference on stuborn bolts. If you dont have one, get an impact screwdriver, you will use it a lot.
Prokop
_______________
Pure Gas - find ethanol free gas station near you

I love it when parts come together.

Dorothy - my CB750
CB750K3F - The Red
Sidecar


CB900C

2006 KLR650

Offline SOHC4 Cafe Racer Fan

  • Speak up, Whipper-Snapper! I'm a
  • Really Old Timer ...
  • *******
  • Posts: 15,731
  • SOHC/4 Member #1235
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #6 on: January 28, 2015, 02:19:54 PM »
+++++1 on the impact driver.  It will save you a boatload of time and frustration.
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 edwardmorris

  • Youngish
  • Old Timer
  • ******
  • Posts: 3,142
  • Do not cause harm, nor respond to harm with harm.
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #7 on: January 28, 2015, 02:23:11 PM »
+1 JIS drivers and impact driver.

Best one http://shop.rrrtoolsolutions.com/4-Bit-Mechanics-Shop-Impact-Driver-Vessel-2500-RRR4IMPACT.htm

Sold by a long time member here, Gordon/ilbikes. He's sold out of the 4-piece set that covers everything for the 750s but you can PM him for special orders.

Offline Restoration Fan

  • My wife will never call me
  • Master
  • *****
  • Posts: 1,966
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #8 on: January 28, 2015, 02:25:03 PM »
That hose you mention is connected to the breather that sits on the bottom of the battery box.  Yours actually has the stopper still in it, like it is supposed to have.  Mine was missing that stopper.

Also, you can download the 78 specific manuals here, which are more detailed than the 69-78 one.

https://drive.google.com/folderview?id=0B4nqeBb662mZZjZjTWdGRk9Qd0E&usp=sharing
« Last Edit: January 28, 2015, 02:29:50 PM by Restoration Fan »
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 goldarrow

  • one day, i'll be an
  • Old Timer
  • ******
  • Posts: 3,361
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #9 on: January 28, 2015, 02:28:39 PM »
Curious what the engine bottom end tranny stuff look like, splitting the cases???

Subscribed...
Life Is Full Of Challenges - And My Backyard Is Full Of SOHC4's

CB550 K0
CB750 K0, K2, K23 JDM, K45, K5
And the little ones z50r, xr50r, st90


750k5 http://forums.sohc4.net/index.php?topic=114817.0

Offline rb550four

  • Master
  • *****
  • Posts: 2,472
  • I'm nobody's slave and nobody's master
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #10 on: January 28, 2015, 02:57:10 PM »
Being that you are in  Gold Coast Florida, which does have allot of sand, high water table ,and hurricanes. I would guess the "mouse" would have been on it's  left side for a bit ,and possibly in high water , maybe not sunk but close enough to the ground to get a sandy splash back or something like that, ... anyways , I was wondering how much sand was in the exhaust pipes and if the sand could have entered the pipes and air cleaner, dried out, and just settled where you found it ?Did PO live close to the surf?
  You are just removing the engine and taking it down without trying to make it turn right? I've seen that powdery fuzz inside a motor that I suspect was under fresh water before, fresh water-salt water doesn't make much diff really.My motor had fuzz throughout the entire inside of the tranny too, found all bearings un-useable, cases and aluminum parts difficult to clean ( Thought about bead blasting all aluminum parts) Shifter forks nearly rusted together.... Not trying to bum you out , but you are going to have to be super thorough with this engine and transmission so your investment of time and money does not go to waste.
  I like projects that are just beat, looks like a fun time,  and I'm interested to see how you treat  this project.
A few Honda 500's, a few Honda 550's, a few Honda 650's, '72 cb 450, a couple 500/550/650 hybrids, and 2001 750. 
  550 Snowbike -Somebody had to do it.
  http://forums.sohc4.net/index.php/topic,101678.0.html             
http://forums.sohc4.net/index.php/topic,137317.msg1550907.html#msg1550907

Offline SOHC4 Cafe Racer Fan

  • Speak up, Whipper-Snapper! I'm a
  • Really Old Timer ...
  • *******
  • Posts: 15,731
  • SOHC/4 Member #1235
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #11 on: January 28, 2015, 03:06:09 PM »
With the SAND issue and it likely being submerged in water, this one makes me wonder if Phinn might be better off parting this one out for money towards a bike in better shape.  You could spend the time tearing it down and keeping any good items and then selling off the questionable parts. 
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 rb550four

  • Master
  • *****
  • Posts: 2,472
  • I'm nobody's slave and nobody's master
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #12 on: January 28, 2015, 03:46:38 PM »
Could be , never know until he takes it all apart to see what he's got.
 Everything is repairable with enough parts and the 750 seems well covered. The thing that I'm wondering about besides the overall interior condition, would be the  cover/case that has been taking a beating even after the crash bars were installed...would also include searching for stress cracks in that area on the engine , and a close look for tell tale tweaks on the frame since it's been down so many times. And overall frame condition ( Rust ) should also checked out... is it just surface or pinholes too or  rot.  The left side bar next to the spine ,over the engine going to the neck didn't look good to me ,like it has separated at the weld. maybe it's just the picture angle. Also behind the swing arm bolt mount on the weld at the V , is that a weep hole or rot?Think everything needs a good lookin' over .
   I was checking out the pics on the left side under the tank...did that look like the petcock nut was rusted? as was the lower end of the tank...wonder what the bottom and inside looks like.
« Last Edit: January 28, 2015, 04:04:16 PM by rb550four »
A few Honda 500's, a few Honda 550's, a few Honda 650's, '72 cb 450, a couple 500/550/650 hybrids, and 2001 750. 
  550 Snowbike -Somebody had to do it.
  http://forums.sohc4.net/index.php/topic,101678.0.html             
http://forums.sohc4.net/index.php/topic,137317.msg1550907.html#msg1550907

Offline martin99

  • UK Based, Non-
  • Master
  • *****
  • Posts: 1,733
  • Adventure before Dementia
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #13 on: January 28, 2015, 03:48:22 PM »
On the road in a few weeks? What's wrong with you man? Just clean up those plugs and you'll be up and running by the weekend! ;D

Best of luck. looking forward to this one :)
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

  • My wife will never call me
  • Master
  • *****
  • Posts: 1,966
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #14 on: January 28, 2015, 04:32:05 PM »
For getting rid of rust, I also highly recommend getting yourself some Metal Rescue.
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 Phinn

  • Subversive
  • Enthusiast
  • **
  • Posts: 224
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #15 on: January 28, 2015, 07:50:33 PM »
Are you simply trying to get it to be a runner, or any design changes during the process.

Phase I is just to get it running.  It's so beaten up that it will never be close to original again, but I'm not planning to go crazy with the customization either.   I'm just pulling together an image folder with a collection of ideas.  I'll sift through it as I go along and come up with something.  My brain is kind of random that way.

If you mean the relay by ignition switch, it is rebuildable too. 

No, the main ignition switch, with the key.  I had to cut the plastic bottom piece off of the assembly.  It was so packed with sand that it was impossible to push the key in to engage the "Park" bolt.  The relay under the seat appears to be fine.

Being that you are in  Gold Coast Florida, which does have allot of sand, high water table ,and hurricanes. I would guess the "mouse" would have been on it's  left side for a bit ,and possibly in high water , maybe not sunk but close enough to the ground to get a sandy splash back or something like that, ... anyways , I was wondering how much sand was in the exhaust pipes and if the sand could have entered the pipes and air cleaner, dried out, and just settled where you found it ?Did PO live close to the surf?
  You are just removing the engine and taking it down without trying to make it turn right? I've seen that powdery fuzz inside a motor that I suspect was under fresh water before, fresh water-salt water doesn't make much diff really.My motor had fuzz throughout the entire inside of the tranny too, found all bearings un-useable, cases and aluminum parts difficult to clean ( Thought about bead blasting all aluminum parts) Shifter forks nearly rusted together.... Not trying to bum you out , but you are going to have to be super thorough with this engine and transmission so your investment of time and money does not go to waste.

The "under the ocean" thing was a joke -- I sure hope it's not true!  I had the bike shipped to me here on the Treasure Coast from Michigan.  As far as I know, it spent its whole life in the frozen North. 

I am not trying to turn the engine.  As soon as I stuck my finger in the exhaust port and came out with a clump of sand, I figured the cylinders had to come off.  There's no amount of Mystery Oil and PB Blaster that's going to convince me that it's safe to run, until I see it with my own eyes. 

   I was checking out the pics on the left side under the tank...did that look like the petcock nut was rusted? as was the lower end of the tank...wonder what the bottom and inside looks like.

Yes, the petcock nut is rusted, but the inside of the tank isn't bad!   No leaks.  No major rust.  Strange, I know.
« Last Edit: January 28, 2015, 08:10:39 PM by Phinn »
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Phinn

  • Subversive
  • Enthusiast
  • **
  • Posts: 224
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #16 on: January 28, 2015, 07:59:20 PM »
I got the various bolts removed, with several cans of PB Blaster, a rudimentary knowledge of metallurgy, burning hatred and sheer force of will.  The "B" engine mount hanger bolt was bent, on the right side, as it emerged from the right side of the frame.  I guess the bike must have down on that side, at least once.  I tried to pull the bolt out for a while, before giving up and just cutting off the offending bent part.  It came right out after that.

I even managed to get the engine out without injuring myself.




The valve cover came off.  Since the engine is seized, and it's exactly 90 degrees out of position, I couldn't reach both of the bolts that hold the cam sprocket in place. So I had to break the cam chain to get the cam out.

I think some of the oil return holes aren't open. 


The problem is the left-most cam bearing.  Not good.


This isn't supposed to be in between the bearing surfaces.


The camshaft might as well have been mounted on a lathe.  It's missing some mass. 


It looks like I'll be upgrading the cam ahead of schedule.
« Last Edit: February 02, 2015, 01:56:12 PM by Phinn »
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline rb550four

  • Master
  • *****
  • Posts: 2,472
  • I'm nobody's slave and nobody's master
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #17 on: January 29, 2015, 04:54:05 PM »
Getting down to the nitty gritty. Custom cut cam, don't see that every day. Can hardly wait to see the rest of it.
A few Honda 500's, a few Honda 550's, a few Honda 650's, '72 cb 450, a couple 500/550/650 hybrids, and 2001 750. 
  550 Snowbike -Somebody had to do it.
  http://forums.sohc4.net/index.php/topic,101678.0.html             
http://forums.sohc4.net/index.php/topic,137317.msg1550907.html#msg1550907

Offline Phinn

  • Subversive
  • Enthusiast
  • **
  • Posts: 224
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #18 on: January 30, 2015, 05:29:31 AM »
Getting down to the nitty gritty. Custom cut cam, don't see that every day. Can hardly wait to see the rest of it.

Yeah, this one's more gritty than nitty.

The strange thing is that the rest of the camshaft seems to be relatively ok. The other three bearing surfaces are in spec, while this one (on the far left) had two clumps of metal in it that ate away maybe 10-15% of that bearing's mass. The lobes look good too. I wouldn't have expected the damage to be so extreme yet so isolated. Considering the general abuse the bike has suffered, I assume the root cause was oil deprivation (although the Vindictive Girlfriend theory is more interesting.)

Since I'm already impelled to do a fairly invasive rebuild, I may go ahead and bore it out to 836cc while I'm here. Does anyone have any thoughts on a good all-around camshaft for a '78 with the 836 kit? (I'm not looking to maximize low end acceleration.)
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline calj737

  • Really Old Timer ...
  • *******
  • Posts: 21,033
  • I refuse...
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #19 on: January 30, 2015, 05:33:43 AM »
Lots of folks either use a a MegaCycle cam or a WebCam with their engine projects. Some decent valve train work and porting is the perfect companion for the 836 upgrade. Be aware, the new reground cams require hard weld rockers.

You can contact Mike Rieck for head work and cam/rockers.
'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 Phinn

  • Subversive
  • Enthusiast
  • **
  • Posts: 224
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #20 on: February 02, 2015, 07:25:03 AM »
I got the head off. 


I see why the engine is seized, but I honestly have no idea how you could cause the inside of a cylinder to end up like this.


There's about a tablespoon of sand, grit, carbon and general debris inside each one.
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Restoration Fan

  • My wife will never call me
  • Master
  • *****
  • Posts: 1,966
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #21 on: February 02, 2015, 08:12:46 AM »
Was the bike sitting outside?  If so, were the spark plugs taken out?  If so, some debris, dirt, moisture, etc will naturally make it's way down into those holes and into the cylinders.
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 Phinn

  • Subversive
  • Enthusiast
  • **
  • Posts: 224
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #22 on: February 22, 2015, 10:08:19 AM »
Was the bike sitting outside?  If so, were the spark plugs taken out?  If so, some debris, dirt, moisture, etc will naturally make it's way down into those holes and into the cylinders.

The spark plugs were in.  The seller says it was in a garage, but who knows? 
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Phinn

  • Subversive
  • Enthusiast
  • **
  • Posts: 224
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #23 on: February 22, 2015, 10:12:46 AM »
After a few failed attempts (solvents, prying, fire, etc.), I was able to get the seized pistons out and the cylinders off.  I used a rented 2-jaw puller from my FLAPS, and pressed the offending piston out.  It was the No. 1 that was stuck the most.  The bike was leaning in that direction for 15-20 years, I guess, with the exhaust valve open.



It was a bit messy in there.

« Last Edit: February 22, 2015, 10:15:29 AM by Phinn »
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Restoration Fan

  • My wife will never call me
  • Master
  • *****
  • Posts: 1,966
Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #24 on: February 23, 2015, 03:48:42 AM »
Congrats on your persistence.  Looks like you'll be going with an overbore kit and a new camshaft.  Have you decided what kind and what size yet?
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