Author Topic: CB750 K7  (Read 8194 times)

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Offline Blasbo

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CB750 K7
« on: August 25, 2008, 02:10:52 PM »
I've been looking for something for a few years on and off and finally found it on craigslist. I picked up a very used 78 or 77 CB750. The guy selling it wasn't sure but the seat looks like a 77.
I was googling for manuals and found the manual thread and started poking around and saw how much great information there is here.
It's locked up and after posting on the noob thread I got good advice from Artfrombama and burmashave. I also somehow lost the only key in less than 24 hours but thanks to this forum know a way to make my own.
My goal is to have something safe, cheap and fun to ride. I'm not looking to do a restoration, more of a rehabilitation. I am not planning on getting in a hurry, it's something to tinker with and I can say "Yeah, I did it myself."
Thanks in advance for advice and encouragement.
« Last Edit: February 09, 2012, 10:39:00 AM by Blasbo »

Offline kslrr

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Re: 1977(I think) CB750
« Reply #1 on: August 25, 2008, 02:16:58 PM »
Welcome.  It's great to see one more member willing to save these great bikes!
Now  1972 CB350FX (experimental v2.0)
        1981 CB650c Custom with '79 engine (wifes)
        1981 CB650 engine
        2004 HD XL883C Custom
        1977 Yamaha XS750D (in progress)
Then 1972 CL175
        1964 Yamaha YGS-1T
No ride is a Bad ride

martino1972

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Re: 1977(I think) CB750
« Reply #2 on: August 25, 2008, 02:32:02 PM »
and it looks like you got a great starting point there,bike looks very restorable...

Offline Blasbo

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Re: 1977(I think) CB750
« Reply #3 on: September 03, 2008, 07:58:17 PM »
Thanks to Super White Pasty Guy I now have a working key that fits the ignition and seat!
Mine came apart a little different than his so here's a pic that may help someone else.
The chrome cover had three "punches" I had to drill out then I finally figured out I had to take out the bottom plastic parts. I ran in to trouble there, the plastic was old and rotten and the tabs that hold it in the ignition broke when I tried to get them out. Then I cracked it in two as you can see by the picture. After that it was pretty straightforward, push the cylinder out with a small screwdriver, find a key, line up the pins and cut.They key is an Ilco X84 HD74. The guy at the friendly neighborhood hardware store said it was a Yamaha key FWIW.
My question now is what can I do to replace/repair/jerry rig the broken plastic piece?

Offline Blasbo

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Re: 1977 CB750 K7
« Reply #4 on: September 10, 2008, 03:03:12 PM »
I was looking through the Post your Favorite MC links and saw where 81-650c posted
www.partsnmore.com. They sell individual parts of the ignition. The part I need is Part#12-0065 for only $3. Minimum order is $35 but I don't think I will have a hard time finding $33 more of stuff I need!

Offline UnCrash

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Re: 1977(I think) CB750
« Reply #5 on: September 10, 2008, 07:01:09 PM »
It's awesome to find that parts are still available for things like this.

Best of luck getting her back on the road.
You can't make too much popcorn, but you can definately eat too much popcorn.

Offline Blasbo

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Re: 1977 CB750
« Reply #6 on: January 16, 2009, 03:19:37 PM »
OK, time to start getting serious about this.
The engine is not locked up. It may have never been. After soaking, it still wasn't turning. The PO had said something about the chain being dry and hard to turn. I was going to take it off and soak it in kerosene but when I loosened the rear brake, the wheel started turning even while in gear.
After lurking and searching I decided to go with a stock airbox instead of buying three more pods because it sounded like it was easier to get the carbs adjusted. (I read a book years ago that said carburetor was a French word for don't fool with it!)
This is what I am planning on doing:
Buying battery, points, plugs, condenser
Drain ATF/Acetone mix and put in fresh oil
Clean and rebuild carbs
Clean out gas tank so I don't have to clean the carbs again
Or should I slap on the airbox, change the oil and see if it will fire up?

This is my first time with anything like this so any and all feedback is appreciated.

Offline BobbyR

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Re: 1977(I think) CB750
« Reply #7 on: January 17, 2009, 07:50:28 PM »
I  think you have the makings of a nice bike. I would put a bit of Marvel, ATF  or any thin oil in the cylinders before you start just to avoid a dry start. You may want to put an inline fuel filter in it to catch any loose stuff. Except for the seat it looks like some black Rustoleum on the frame and some buffing rouge on the cases and you are good to go. My bike is still what I call a rolling restoration. After I got it running well and looking OK. I Each year I do something to make it better.
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Offline Blasbo

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Re: CB750 K7
« Reply #8 on: February 09, 2012, 10:54:09 AM »
The clutch cable was messed up; that's why it would turn when it was in gear. After I took the cable off it's stuck tight.
The ATF/Acetone didn't free it up so I put it was time to take the engine out. I liked the C hook idea and built one out of some angle iron I had already. It did the job, but it isn't strong enough. When I was wrestling the motor on to my bench it twisted. I am planning on building one out of pipe when I put it back in.

Offline Really?

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Re: CB750 K7
« Reply #9 on: February 09, 2012, 10:57:38 AM »
Took you that long to figure out the cable?  :) :) :)
I don't have a motorcycle, sold it ('85 Yamaha Venture Royale).  Haven't had a CB750 for over 40 years.

The Wife's Bike - 750K5
The Kid's Bike - 750K3

Offline Blasbo

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Re: CB750 K7
« Reply #10 on: February 09, 2012, 11:04:28 AM »
Nah, took me that long to figure out that whenever I finished something on my honey-do list; thinking I could work on the bike next; my wife would put something else on my list!  ;D

Offline Blasbo

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Re: CB750 K7
« Reply #11 on: February 09, 2012, 11:12:23 AM »
Got the valve cover off. This doesn't look so bad.
Got the cylinder head off.  :o Uh oh, this doesn't look so good. I can see why the ATF/Acetone didn't work.
The liquid is ATF, the acetone has evaporated.
« Last Edit: February 09, 2012, 11:14:21 AM by Blasbo »