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Author Topic: '79 CB750 K  (Read 1481 times)

Offline advCo

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    • adventur Studios
Re: '79 CB750 K
« Reply #10 on: Feb 19, 2019, 14:12:20 »
I did my hubs like that, but painted the entire thing black and then used a paint pen to color the fins gold.

I like to keep my paint indoors if its going to be cold out, along with the part to keep it at room temp. Spray and then keep a space heater near it and should be good to go. Good progress so far though.

Offline Nybz

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Re: '79 CB750 K
« Reply #11 on: Feb 20, 2019, 15:22:22 »
Carb rebuild using Randakk kits. Very highly recommend. All vitron o rings and includes all air cut offs, and accelerator pump.
Here is a great carb rebuild guide, such a great resource. Print it off and follow everything! Especially the part about clearing the slow air passage.

https://www.dropbox.com/s/ufw8lra6jj6fgcq/Honda_Carb_Manual_revG.pdf?dl=0

Getting the engine apart....kinda not so funny story....I wasn’t going to separate the cases, just clean up the head and new gaskets and seals.
I have this oil seal kit and I saw this counter shaft oil seal behind the front sprocket. So I am like I will just remove this and replace it. So I screw a screw into the seal to remove it.....I am screwed! The seal has a lip in it that can’t be pulled out without separating the cases!
So I ended up splitting the cases and found my main bearing were toast anyways. The copper showing is no good. It must have been oil starved or dirty at some point, cause there is only 20k km on the engine.

So I ordered all new main and rod bearings(Not f’n cheap!) and some Hondabond. There is a few o rings down there too I replaced. Everything else in the transmission is copacetic.

Had one of the case bolts snap on me after I read the wrong torque valve...careful! Lucky I just went into my local fastener shop and they matched me up a bolt to fit.

A alittle tip for reattaching the cases together, is to tie down the primary chain tensioner until the cases are together. Helps with keeping things together, cause there is little bits in there that like to jump out. Then just cut it out or untie.

Fun times!


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1979 CB750 LTD collectors plates
1979 CB750 K current custom rebuild
1980 CB750 F in waiting...

Past bikes
1982 GL1100
1980 CB400

Offline Nybz

  • Posts: 31
'79 CB750 K
« Reply #12 on: Feb 21, 2019, 01:07:29 »
oh yeah....and while in the engine found some deep rust pitting in one of the cylinders.
Tried to hone it out, but it was too deep to keep within spec, so I got the cylinders rebored and got new pistons and rings from cruzinimage. 1 MM bore to 63 mm total

The 1979 CB750 had problems with the four back middle cylinder studs leaking oil from fractures in the case....so following the 1979 service bulletin put out by Honda, I took out the back studs and put high temp sealant on the threads to seal them up.

Sorry for the crap photos....in the second picture you can see the top of the new cam chain tensioner.
« Last Edit: Feb 21, 2019, 03:03:31 by Nybz »
1979 CB750 LTD collectors plates
1979 CB750 K current custom rebuild
1980 CB750 F in waiting...

Past bikes
1982 GL1100
1980 CB400

Offline Jimbonaut

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Re: '79 CB750 K
« Reply #13 on: Feb 21, 2019, 10:55:28 »
Looking good - is that the tensioner from Captain (Brent)?  I got in touch with him re. his overhead tensioner as my oem one is busted.  Did you get his overhead tensioner too?
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline Nybz

  • Posts: 31
'79 CB750 K
« Reply #14 on: Feb 23, 2019, 04:43:07 »
I didn’t get the B chain tensioner..... It can be removed without removing the engine for the frame so i opted to not get it, as my B tensioner still looked good. But yeah replace it with something better if it is busted.

The A chain takes more force and is a case splitter, so I took care of that the best I could.

On 1979 models the B chain GUIDE is alittle bit more weaker then the rest of the DOHC line. Mine had a broken leg attaching to the cam holders. Must have been a loud rattle when running, I wouldn’t know.
But I got it replaced with a later model DOHC, which is stronger.

You can see in the picture 900 cams, new high quality A and B cam chains(M), upgraded cam holder bolts and the ‘new old’ b chain guide that has to be bent to fit the new A chain tensioner. I heated up the copper washers under the cylinder head nuts to help them seal (anele?) , and added a bit of case sealer as back up.


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« Last Edit: Feb 23, 2019, 04:48:43 by Nybz »
1979 CB750 LTD collectors plates
1979 CB750 K current custom rebuild
1980 CB750 F in waiting...

Past bikes
1982 GL1100
1980 CB400

Offline cxman

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Re: '79 CB750 K
« Reply #15 on: Feb 23, 2019, 08:53:29 »
make sure while you are in there you remove inspect and loctite and torque the three starter clutch bolts just behind the advancer
they are notorious on all the dohcs for working loose and causing a "rod knock"

if your bolts have been rattling put in new ones
1978 CX650 Super Deluxe
1979 XS1100 Special
1974 xl350
1983 cx650 Custom
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1974 kawasaki 350 bighorn
1983 GL1100 aspy full dress
1983 GL1100 Nekid
and a bunch of others

Offline Jimbonaut

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    • Lost Apostle
Re: '79 CB750 K
« Reply #16 on: Feb 23, 2019, 20:36:38 »
I can absolutely attest to that - had a loud knocking from the side of the engine on my other 750 which turned out to be loose starter clutch bolts. Loctite and torque and job’s a good’un.


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"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline Nybz

  • Posts: 31
Re: '79 CB750 K
« Reply #17 on: Feb 24, 2019, 00:02:00 »
Done and done thanks

I do have a starter clutch rebuild kit as well that I will wait to install depending on what bike needs it. My LTD just spins sometimes without engaging, so will probably be that one.


Sent from my iPhone using DO THE TON
1979 CB750 LTD collectors plates
1979 CB750 K current custom rebuild
1980 CB750 F in waiting...

Past bikes
1982 GL1100
1980 CB400

Offline cxman

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Re: '79 CB750 K
« Reply #18 on: Feb 24, 2019, 16:04:20 »
if its a aftermarket rebuild kit use honda springs with it

aftermarket ones fail in weeks
1978 CX650 Super Deluxe
1979 XS1100 Special
1974 xl350
1983 cx650 Custom
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1974 kawasaki 350 bighorn
1983 GL1100 aspy full dress
1983 GL1100 Nekid
and a bunch of others

Offline Jimbonaut

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Re: '79 CB750 K
« Reply #19 on: Feb 25, 2019, 11:21:23 »
Hey man glad you posted that image of your cylinder head.  Reading the Clymers while I was dismantling mine it mentioned something about two rubber caps on two cylinder bolts which, in my cylinder head, weren't there.  These things -



I can't find them on any parts fiche, and I'm wondering what they actually do?
"I'm telling you Donnie, nuthin' but nuthin' but right"