CB750 K0/K1 Hybrid

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Easter
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Re: CB750 K2- New Presents!

#31

Post by Easter »

Congrats on the bike, didn't realize it had become yours. My 750 project is as promised, moving very slowly. Expect to get the modified frame back from the machine shop next week and I now have the steering head from the XR600 modified to fit the 750 frame. I plan to bolt it together with the wheels, minus engine, just to see how it sets and if the mono shock is going to work as planned. I will update my post in a week or so when this all comes together.
Great score on the new (used) pipes. You can install studs and bolts. I am pretty sure my '72 had them and I know my '78 has them because I couldn't get them out to remove the engine from the frame!! Finally did get it out.
Bikes at present:

83 XL 600r with a 2004 XR650L engine
And a slightly worse for the wear BMW GS adventure bike awaiting repair
83 GL in process :IDTS:
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Lucien Harpress
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Re: CB750 K2- When you Have a Hoist....

#32

Post by Lucien Harpress »

This afternoon, my back started to go out. (I'm only 28, but it happens.) This gave me a great idea....

Image

...remember what I said about the CB750 being dead-easy to work on? Yeah, I found the point where it isn't. The engine was so tight to the frame I couldn't use my regular lifting straps, and had to improvise with ratchet straps. Even then, getting it out by myself was a PITA. I started looking up 750 engine removal techniques, and there really isn't a good way to do it.

Getting this back in after paint is going to be... an experience.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
JSBail
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Re: CB750 K2- When you Have a Hoist....

#33

Post by JSBail »

Yep I was shocked when I found out on the first 750 I had that you had to pull the engine just to remove the valve cover and yep those engines are heavy. I've got a frame kit on my 77 that allows me to remove a section of the frame which allows me to service the engine with ease and makes removing/installing the engine much easier too and when I'm done the section of frame goes right back in place. I'll post some pics of it later when I get back from work.
Scott
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luludog
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Re: CB750 K2- When you Have a Hoist....

#34

Post by luludog »

Great bike & project. Easiest way to install the engine is to lay the engine on its side and slide the frame over it. After you get the bolts and brackets in place loosely; right the frame/engine and finish tightening. Good luck. Look forward to seeing your progress.
-Ray

1977 GL1000 - http://www.ngwclub.com/forum/viewtopic.php?f=30&t=40398
1975 CB750K5 - stock restoration http://www.ngwclub.com/forum/viewtopic.php?f=13&t=40426
1971 CB175K5 - stock restoration http://www.ngwclub.com/forum/viewtopic. ... 95&start=0
1972 CB350 - resto-mod cafe project http://www.ngwclub.com/forum/viewtopic.php?f=30&t=47429


"Remembering the Past... Liv'n the Dream"
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Easter
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Re: CB750 K2- When you Have a Hoist....

#35

Post by Easter »

luludog wrote:Great bike & project. Easiest way to install the engine is to lay the engine on its side and slide the frame over it. After you get the bolts and brackets in place loosely; right the frame/engine and finish tightening. Good luck. Look forward to seeing your progress.
I agree, but if you can't get the exhaust studs out it is still a real pain. Much tighter fit than a wing engine.
Bikes at present:

83 XL 600r with a 2004 XR650L engine
And a slightly worse for the wear BMW GS adventure bike awaiting repair
83 GL in process :IDTS:
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luludog
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Re: CB750 K2- When you Have a Hoist....

#36

Post by luludog »

SOHC 750's are popular, and it seems like there's more & more being rescued & restored :-D

The engine is a tight fit with the exhaust pipe flanges, but doable. Another set of hands really helps.

Here's a few pics from when I did the '75.

Image

Image

Image
-Ray

1977 GL1000 - http://www.ngwclub.com/forum/viewtopic.php?f=30&t=40398
1975 CB750K5 - stock restoration http://www.ngwclub.com/forum/viewtopic.php?f=13&t=40426
1971 CB175K5 - stock restoration http://www.ngwclub.com/forum/viewtopic. ... 95&start=0
1972 CB350 - resto-mod cafe project http://www.ngwclub.com/forum/viewtopic.php?f=30&t=47429


"Remembering the Past... Liv'n the Dream"
JSBail
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Re: CB750 K2- When you Have a Hoist....

#37

Post by JSBail »

In the pick you'll see the aluminum "sliders" (2 on each side) that clamp over the section of the frame that was cut with a tubing cutter and the area that I'm pointing at sets an aluminum plate to support that area that had to be cut. The actual spine tube of the frame was left intact, it's just those side tubes that were cut. To remove I just loosen all the screws on the sliders and move them to the side then unscrew the plate I'm point to and that section of the frame drops out. Everything is actually a tight fit, the sliders once they're loosened have to be persuaded with a piece of wood and a small hammer and that frame section doesn't just plop out because the tubing cutter left almost no clearance on the cut. That in itself is a good thing because if for what ever reason I want the bike completely stock again I can easily weld the frame section in place and with some careful use of a grinder you wouldn't know any mod had ever been done... unless you looked really hard.

The mod isn't for everyone, if you plan on rebuilding your engine right the first time and have no intentions of ever taking it apart again or at least not for a long time then there's no point in the mod but if you're someone like me that's always trying something different to get more HP which more times than not means the engine will have to come apart again at some point then it's worth considering. The frame mod I have requires no welding but others are available where the removable frame section is bolted in place.
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Scott
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Lucien Harpress
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Re: CB750 K2- When you Have a Hoist....

#38

Post by Lucien Harpress »

Yeah, I've seen those frame kits before. I'm hoping that I only have to pull the motor once, and any surgery on the frame (even this minor) makes me nervous. Mostly about my own skills in accomplishing it cleanly.

The plan with this motor is to hopefully not go that deep into it. Main priority is to get the spark plug in cylinder 2 out. Assuming I can get it out without pulling the head, I'd also like to replace the "pucks" under the rocker arm towers. Apparently, they tend to leak (was this brought up on the first page of this thread? I think so), and I'm hoping that explains my big black 30-year-old stain on the front of my engine.

After that, it's a general clean-up, light polish job, and a quick coat of paint for the engine and as much of the frame as I can reach, and back in the frame she goes. Then it's full steam ahead on getting the engine running. I'm willing to pull the motor again to change a head gasket if need be, but I doubt I'm going any deeper than that.

(Funny enough, the exhaust studs were never an issue. I've got all 4 collars unscrewed and out of the engine, which may help- 3 of them are still frozen into my old exhaust pipes. In any case, it was the valve cover and lower right engine mount that gave me the most trouble. We'll see about getting it back in when the time comes.)
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
JSBail
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Re: CB750 K2- When you Have a Hoist....

#39

Post by JSBail »

Cutting mine made me nervous too, I didn't just measure twice cut once it was more like measure 4 or 5 times cut once. As far as the pucks under the cam holders you may want to consider genuine Honda pucks. I've never had an issue with aftermarket gasket sets except for those rubber pucks, the ones that come with aftermarket kits tend to be thinner than the OEM ones and I had issues getting them to seal on my 750. There are ways of making them seal like they should but I said phooey on that and just bought genuine Honda pucks instead and that took care of it.
Scott
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luludog
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Re: CB750 K2- When you Have a Hoist....

#40

Post by luludog »

+1 on using the Honda "pucks" (#17). I'd also get the o-rings for the oil port orifices (#16)

Image
-Ray

1977 GL1000 - http://www.ngwclub.com/forum/viewtopic.php?f=30&t=40398
1975 CB750K5 - stock restoration http://www.ngwclub.com/forum/viewtopic.php?f=13&t=40426
1971 CB175K5 - stock restoration http://www.ngwclub.com/forum/viewtopic. ... 95&start=0
1972 CB350 - resto-mod cafe project http://www.ngwclub.com/forum/viewtopic.php?f=30&t=47429


"Remembering the Past... Liv'n the Dream"
User avatar
Easter
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Re: CB750 K2- When you Have a Hoist....

#41

Post by Easter »

I started cleaning up my CB750 engine ("long term CB 750 project") some time back and ran out of soda, then today I had the blaster out trying to clean up the wheels on the GL1000 project I am working on so I drug out the CB engine to finish the job. Boy, what a project! Took about 3 hours and 50 pounds of soda. I don't know when I will get back to it, this is a long term project, but at least it looks like an engine instead of a greasy, crusty pile of junk. Now if I can just get the exhaust studs out. Hope I don't have to take the whole thing apart but if I do I will take the cylinders to a machine shop and let them get them out.
Bikes at present:

83 XL 600r with a 2004 XR650L engine
And a slightly worse for the wear BMW GS adventure bike awaiting repair
83 GL in process :IDTS:
gschlabaugh
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Re: CB750 K2- When you Have a Hoist....

#42

Post by gschlabaugh »

I have had the same problems listed by others when building my CB750 "tracker" getting the engine out of the frame and back in again. Found the best way was to lay the bike on its side and lift the frame off the engine; same with putting it back together. Mine had been laying against a tree for at least 20 years so the rims were almost rusted through, seat was missing, wiring harness was badly cut up with a lot of splices no air filter box. The oil filter bolt was rounded off so it would not come off. I repainted the frame used a KZ750 gas tank as the Honda stock one was rusted through. Ordered a seat from "Hot Wings" It is back together now, still working on getting it to run.
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Gary
1975 GL1000, 1978 KZ 750 twin streettracker, 2002 Buell X1,1978 GL1000
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Easter
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Re: CB750 K2- When you Have a Hoist....

#43

Post by Easter »

Looks really sharp. Nice work. I have been side-tracked on other projects so nothing more has happened with mine but I think about it a lot!!
Bikes at present:

83 XL 600r with a 2004 XR650L engine
And a slightly worse for the wear BMW GS adventure bike awaiting repair
83 GL in process :IDTS:
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Lucien Harpress
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Re: CB750 K2- When you Have a Hoist....

#44

Post by Lucien Harpress »

I hear you. Most of my time lately has been directed at my GL1200, as that thing is nearly 100%. However, I was able to fit a new set of right controls and start taking the valve cover off my 750.

True, I managed to strip half of them, even with an Impact, so the rest will need drilled out and replaced. On the plus side, replacement bolts are available, AND I got my spark plug out as well.

Valve cover off soon for me? I hope so...
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
User avatar
Easter
True Blue Steel Biker
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Posts: 2999
Joined: Thu Sep 13, 2012 11:33 am
Location: South of Houston 100 miles

Re: CB750 K2- When you Have a Hoist....

#45

Post by Easter »

Lucien, I have an appointment to look at an '86 Aspencade tonight. Hope to pick it up. Not sure where I will go with it but your 1200 is a target to aim for.
Bikes at present:

83 XL 600r with a 2004 XR650L engine
And a slightly worse for the wear BMW GS adventure bike awaiting repair
83 GL in process :IDTS:
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