Author Topic: "Mouse" - a 1978 CB750K project [PICS]  (Read 13994 times)

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Offline FridgeRaider

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Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #25 on: February 23, 2015, 06:50:26 AM »
Looks like you'll be going with an overbore kit and a new camshaft.  Have you decided what kind and what size yet?


+1 and subscribed
1972 CB750K2 Resto-mod (836cc Upgrade) - http://forums.sohc4.net/index.php/topic,161782.0.html

Offline Phinn

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Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #26 on: February 23, 2015, 09:46:02 AM »
836cc seems like the simplest route, but I'm still researching the options and the cam/valvetrain choices that would go with it. I have a couple of weekends of disassembly to go before I turn the corner and start putting it back together.
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Phinn

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Re: "Mouse" - my 1978 CB750K project [PICS]
« Reply #27 on: July 26, 2015, 01:57:51 PM »
I've made some progress.  I've been focusing on the engine.  I split it open, cleaned it out and sealed it back up.  It went fairly well. Love that Threebond.



I decided not to go with the 836cc pistons.  I figure that, to do an 836 justice, you'd also need a new cam, a ported head, valve guides, and maybe even new rods, etc.  Mouse is awesome, in sort of a gritty, scrappy way, but isn't really a good candidate for that sort of across-the-board upgrade.  So, instead I went with a set of 4th oversize (+1.00) pistons from CycleX.  I also got the heavy duty studs from APE.



The cylinders have been bored to match.  They cleaned the surfaces and extracted the two rusted-solid knock pins as well --



The pistons look great, but one of them isn't quite right.  The first three went in like a breeze, but the rings on the final one wouldn't seat properly.  I'll have to swap that one out.



Another couple of weeks, and this one will be on the road again!
« Last Edit: July 27, 2015, 11:47:17 AM by Phinn »
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Phinn

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #28 on: July 27, 2015, 11:48:29 AM »
Looking back over the last few months, I realize I've bought more parts than I remembered.  This is just the basic stuff needed to get the bike running and minimally usable --

  • piston set (CycleX)
  • HD cylinder studs (APE)
  • engine cover bolts (hex head)
  • camshaft
  • camshaft tower
  • cam chain
  • engine gasket set
  • oil seal set
  • clutch plates
  • clutch springs
  • clutch lifter plate
  • clutch cable
  • choke cable
  • exhaust studs
  • battery
  • stator
  • field coil
  • main ignition key switch
  • fuse box
  • starter solenoid
  • spark plugs
  • drive chain
  • chain adjuster bolts
  • brake pads (front)
  • rear shock bushings


And there's still a few things I'll need --

  • dowel pins
  • intake valve (1)
  • wiring harness
  • regulator/rectifier unit
  • carb rebuild kits (4x)
  • carb pump diaphragm kit
  • carb intake clamps
  • fuel hoses
  • seat
  • axle bearings (front & rear)
  • fork seals
  • headlamp brackets
  • side covers

For a "free" bike, it sure does cost a lot.
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Phinn

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #29 on: August 07, 2015, 06:59:16 PM »
I returned the defective piston to CycleX, and found the whole experience to be one of the easiest, most well-handled exchanges I've had in a while. The young guy who answered the phone told me I needed to speak to Ken. A couple of hours later, I talked to Ken and described the problem. He immediately offered to send me a new one. It was shipped out later the same day. All he asked was that I eventually send the old one back, so he could show it to the manufacturer and see how it happened. I was very impressed, and will be buying from them again.

I had a similar good experience earlier in the summer with 4into1.com. I bought a complete gasket set, but the head gasket (the most expensive piece) had a defect. Part of the metallic coating was chipped off, so it had an irregular spot. The owner only asked for a photo so he could see what I was talking about, and then shipped me a replacement that same day.

Both of these vendors handled the situations as well as I could have hoped. I'm building this project on a tight budget, and these problems could have easily set me back at least a couple of months while I saved up for the parts. Both are highly recommended.
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Prez1967

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #30 on: August 08, 2015, 01:06:17 PM »
I certainly see potential in this build and am looking forward to following it. Keep the motivation high my friend!

Offline Phinn

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #31 on: August 09, 2015, 10:22:33 AM »
I installed the new pistons, and thought everything was going well.  I didn't know it was a problem until I cycled the pistons though half a turn, and the 1 and 4 pistons started their downward stroke. 

No go.  A dead halt.  As stuck as stuck gets.

I eventually diagnosed it as the No. 4 piston that was stuck.  I had to pound it out (using the same techniques I'd used earlier to free the frozen original pistons at the start of the project).

Once I got it out, the cause of the trouble was clear -- one of the thin rings that make up the oil ring didn't compress properly.  Instead of sliding neatly into the cylinder, it folded over.



Oh, well.  Another set of rings has been ordered (from my new friends at CycleX), and I will have to find something else to do with my Sunday.

Here's an artist's depiction of my struggles today with this self-inflicted problem --

1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Stev-o

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #32 on: August 09, 2015, 02:37:02 PM »
The cheapest bikes are the most expensive bikes.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline calj737

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #33 on: August 09, 2015, 03:07:06 PM »
The cheapest bikes are the most expensive bikes.
That's because they need everything done to them! Ask me how I know  :'(
'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 Stev-o

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #34 on: August 09, 2015, 03:15:14 PM »
The cheapest bikes are the most expensive bikes.
That's because they need everything done to them! Ask me how I know  :'(

Ask me how I know!   On second, thought, can we just drop it?!
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Phinn

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #35 on: August 09, 2015, 04:27:18 PM »
I am glad to report that, after cursing everyone and everything within a 10 foot radius, I took the afternoon off and regrouped. 

After I calmed down, I remembered that I already had a perfectly good set of virtually new rings, just waiting to replace the one that I crushed/folded in the cylinder earlier.  They were still on the old piston that was sitting in a cardboard box, ready to send back to CycleX. 

So, I scavenged the oil ring components off of the old one, filed a few burrs off the compression ring, and presto -- we have a working cylinder, with four working pistons!   The cylinder slid down onto the knock pins like it belonged there.

Photos will be posted later. 
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Phinn

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #36 on: August 09, 2015, 05:37:38 PM »
The cylinder seated perfectly.



Much cleaner than before --



We have free motion!





I noticed that my "complete" set of gaskets is missing two 11x2.5mm o-rings, which go under the head, so I'll be taking a short break while those are sent, but all in all, it turned out to be a very productive weekend.
« Last Edit: August 09, 2015, 05:51:06 PM by Phinn »
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Stev-o

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #37 on: August 09, 2015, 05:54:29 PM »
This would be a good time to paint that motor.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline SOHC4 Cafe Racer Fan

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #38 on: August 09, 2015, 10:03:49 PM »
This would be a good time to paint that motor.

++++1
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

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #39 on: August 10, 2015, 04:32:58 AM »
This is a great time to have a cold beer (or several) and pat yourself on the back for getting that motor together! Really cool that you got calmed down and used your head (or old rings) instead of throwing a hammer thru the wall. These bikes require more patience than parts, and are a great reminder that to resurrect a 40 year old machine, takes longer than a weekend.
'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

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #40 on: August 10, 2015, 07:28:27 AM »
This would be a good time to paint that motor.

++++1

Take my word for it -- the paint on the engine covers looks fantastic.   ;)  But before I finished the job, I found that stripping the paint off the case itself proved to be far more difficult than expected, and I ran out of enthusiasm.  I was planning to get the whole engine together, then tape off the (fantastic) covers, and finish the paint job that way. 

(Or there's always the "junkyard" look that the kids these days seem to like.)

This is a great time to have a cold beer (or several) and pat yourself on the back for getting that motor together! Really cool that you got calmed down and used your head (or old rings) instead of throwing a hammer thru the wall. These bikes require more patience than parts, and are a great reminder that to resurrect a 40 year old machine, takes longer than a weekend.

Beer was enjoyed, yes! 

And, now that you mention it, the throwing of a hammer also occurred.  Although, to be fair, it was a rubber mallet-type hammer, and I threw it through an open garage door, not a regular hammer through a regular wall.  And, I should point out that, only moments earlier, as I was gently tapping the cylinder block down (in an attempt that would prove to be futile), I accidentally scraped the side of that rubber mallet against the exposed threads of the HD cylinder studs, leaving a large pile of rubber scraping dust inside my freshly-honed, brand new No. 4 piston slot. 

But that's all behind me now.  I spent the last hour of my Sunday, chilling to some good music, as I meticulously picked the crud and carbon out of the nooks and crannies of the cylinder head, which will soon be reassembled. It was slow-going but oddly satisfying.
« Last Edit: August 10, 2015, 09:21:19 AM by Phinn »
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Phinn

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #41 on: August 16, 2015, 07:50:46 AM »
This weekend's project is the cylinder head. It's in fairly good shape.

Here's the "before" photo.



Here it is after a couple of hours of cleaning.



I'm going to polish the combustion domes and get this thing installed.

I wasn't sure about the valves. They were all intact, no nicks, but were fairly crusty. After I'd wire-wheeled them, I thought they might work. So I decided to lap them and see how they turned out.

The results were better than expected --



I'm really happy with how they turned out. I should have a working engine, installed in the frame, by the end of the day. It's starting to look like a bike again!

Next up: the carburetors.
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Restoration Fan

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #42 on: August 16, 2015, 09:00:10 AM »
Nice job on the engine.

Good luck on the carburetors.  To me, that's potentially the most important, yet also most frustrating thing to do with these old bikes. 
For a GREAT reference on re-assembling the carbs on these 78 PD carbs, you should check out this post by Wilbur (aka madmtnmotors).  In my opinion, it should be stickied as a permanent reference on how to do these PD carbs.
http://forums.sohc4.net/index.php/topic,100352.msg1669248.html#msg1669248
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 beemerbum

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #43 on: September 09, 2015, 09:03:27 AM »
New to this forum and loving it. I've learned a huge amount. Any thing new on "mouse"? I got a '71 for free with the motor in boxes. It lived inside all its life so I see it as a restoration project. The PO had installed HD-like floorboards and lost the pegs. Thankfully replaced by E-bay.

Offline Restoration Fan

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #44 on: September 09, 2015, 09:16:22 AM »
New to this forum and loving it. I've learned a huge amount. Any thing new on "mouse"? I got a '71 for free with the motor in boxes. It lived inside all its life so I see it as a restoration project. The PO had installed HD-like floorboards and lost the pegs. Thankfully replaced by E-bay.
Welcome to the forum.  Start a build thread for your bike and post pictures and questions often.  You'll be surprised and pleased at how much help you'll get and how much you'll learn.  And the build thread lets you keep a record of everything all in one place.
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

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #45 on: September 09, 2015, 01:29:25 PM »
New to this forum and loving it. I've learned a huge amount. Any thing new on "mouse"? I got a '71 for free with the motor in boxes. It lived inside all its life so I see it as a restoration project. The PO had installed HD-like floorboards and lost the pegs. Thankfully replaced by E-bay.

Thanks for asking. I've made some good progress this summer. I finished the engine rebuild. I had a disaster or two (had to resplit the sealed case to install a forgotten oil seal; bent an oil ring inside a cylinder, etc.), but I bounced back. The valve head part went very smoothly. I lapped the valves, and everything clicks along normally.

I'm almost done with the carbs. I damaged one fuel mixture screw, so I need to repair the threads. But the other three carbs are great. Very clean. I even managed to get the accelerator pump on carb #2 working again.

Next up: returning the engine to the frame. Then putting the carbs back on. I'll need to redo the clutch plates (I don't think I have them all stacked facing the same direction, as recommended).

Then I'll be installing the replacement electrical parts that are waiting on the shelf -- stator, wiring harness, solenoid, key switch.  Then I'll be able to see which parts of the electrical system are still alive and which are not coming back from the dead.

Then it's just a few small projects away (brake pads, new rear sprocket, etc.) from being roadworthy.

I'll post some more progress pics soon.
« Last Edit: September 09, 2015, 02:22:29 PM by Phinn »
1978 CB750K -- "Mouse," a former basket case, resurrected

Offline Vinhead1957

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #46 on: September 10, 2015, 04:56:14 AM »
Looks like you have a good project there.  Those must be newer carbs 71 did not have an accelerator pump.   I do most of my work during winter months when we are house bound. Prefer to ride the good months.

Offline Vinhead1957

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #47 on: September 10, 2015, 04:57:48 AM »
Don't forget the "book".  Mark's book is the bible in your quest!

Offline Phinn

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #48 on: September 10, 2015, 07:24:11 AM »
Looks like you have a good project there.  Those must be newer carbs 71 did not have an accelerator pump.   I do most of my work during winter months when we are house bound. Prefer to ride the good months.

I'm in Florida, and this summer has been an absolute scorcher. The El Niño effect was in full swing, and every day was in the 90s with extremely high humidity.  I lived in New Orleans, so I know humidity, but I've never seen anything like this. My garage is easily 100 degrees during the daytime, and most of the night. It means my ability to work on the bike has been limited to about 20 minutes at a time.

But at least the paint on my engine covers came out nice.

1978 CB750K -- "Mouse," a former basket case, resurrected

Offline SOHC4 Cafe Racer Fan

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Re: "Mouse" - a 1978 CB750K project [PICS]
« Reply #49 on: September 10, 2015, 08:30:46 AM »
The paint on the cover looks good.

I live in SoCal and we've had the hottest and most humid summer.
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