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Author Topic: '79 CB750 K  (Read 1564 times)

Offline Nybz

  • Posts: 31
'79 CB750 K
« on: Feb 16, 2019, 00:33:40 »
Well it is frick'n cold in the garage and I don't really feel like handling cold metal pieces right now, so I thought I might as well start a build project. Yet another CB750 DOHC! Long live!

My plan was originally to have this bike as a parts bike for my '79 CB750 LTD. Found it for a few hundred bucks, not running.


I got the LTD on the road and running great, so I started to strip down the bike, and I couldn't help but to want to rebuild this bike too. It was pretty rough, but after starting to take it apart it didn't seem like it was that bad to have all broken up in a million pieces sitting on a shelf.


So onwards and forwards!

The boat tail light is pretty rare for the CB750, I believe they were only made that way for one year. There was actually less of these made then the "Limited Edition" bike that I also have. So I wanted to keep some of the 'originalness' of the bike and not do a full blown café or anything like that. I am more of function over form kinda guy.
I wanted to create some sort of zombie apocalypse style bike. I have toned down the idea a bit but still want an aggressive looking black bike with some red accents.

Some background. I am no expert and don't have super fancy tools, but I am passionate, willing to learn, and ALMOST love working on motorbikes then actually riding them. I am a farmer, and the motorbike mechanics world gives me a chance to put my mental energy somewhere else other then the million things that need doing in the field.
I have mostly been active on the two DOHC forums and have gleaned a lot of information from some amazingly knowledge group of people. (what did people do before online forums?)

So I started buying some parts.
Randakk cycle shop full carb rebuild kit....not cheap but highly suggested by the pro's...didn't want to skimp on rebuilding the carbs
New carb rubber insulators
New coils, wires, caps and plugs
Capitan over on the cb1100f forum has made better then stock cam chain tensioners for the A chain and B chain. Not cheap! Ouch, but they are suppose to outlive the bike and dramatically increase the life of the cam chains. So bought those along with new A and B cam chains.
Spokes
wheel bearings
beefy dual sport tires
fork seals
new progressive fork springs
Front caliper rebuild with new piston
After market master cylinder
found some 900 cams...direct swap, more lift and duration...suppose to be great improvement.
clutch springs and fibers. Also got a clutch dampener kits. Which replaces the stock rubber dampeners are rock hard and cause a clutch rattle at idle. (Noticeable on my LTD)
upgraded cam holder bolts
Oil seal kit
gasket set
changed out the huge 630 chain for a new X ring 530 with new sprockets. Keeping stock gear ratios.
Steering head bearings
New shocks


Pretty much my idea is to create a brand new bike, replace any old rubber, replace any parts that are past their prime, reseal the engine, repaint, clean up every nut and bolt.
 
That's it for now....
« Last Edit: Feb 16, 2019, 20:20:50 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

  • DTT BOTM WINNER
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  • Posts: 1881
    • Lost Apostle
Re: '79 CB750 K
« Reply #1 on: Feb 16, 2019, 11:47:47 »
Great intro mate and a great project you're got on your hands there!  I'll be following your build with much interest, particularly as some of the mods you're planning (the cam chain tensioners, the 900 cams etc) are now - having learnt about them over on the other forum you pointed me to - on my radar.  Good call indeed with the Randakk's carb rebuild kit - I bought the same one for my '81 K and never had a problem.

Not sure if it's just me but I can't see the opening photos on your post, just the last 6.

Welcome, and looking forward to watching your ride shape up man
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline Nybz

  • Posts: 31
Re: '79 CB750 K
« Reply #2 on: Feb 16, 2019, 20:13:39 »
Well it is above 0c and I finally got my ass out to the garage.

I have done a bit off work already on the bike that I will post about later, but today is fork day!

Had some pretty bad rust on the top of the fork tubes, but not low enough to effect the seal area, thought about painting it. But I happened to find a spare set of forks from the not so local bike wreckers shop for pretty cheap.

Tubes look great just the lowers are badly painted.
Rebuilding time!
It is alot easier to take apart with them still attached to the triple tree. Made a quick bolt ‘tool’ to help me get off the top cap.

Comparing the new springs I got to the old one, they are smaller but they come with a spacer, which if installed would longer in length then original.
I wonder if I cut the spacer down to size to fit the original length or install it as is, and probably wrestle trying to put the top cap back on.
I got them from vintagecb750, and upon a closer look they say progressive ‘type’ springs. Perhaps I will send them a message.

No matter how many times I try and take out the fork seals it is always PITA! There has got to be a better way!
Tried some heat, WD40, seal remover, curved screwdriver....and yeah I protect the fork lower from damage by prying.
Anyone got a secret?


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 Nybz

  • Posts: 31
'79 CB750 K
« Reply #3 on: Feb 16, 2019, 20:17:49 »
Do these pictures work better?
I tried the do the ton app to post these pictures....had a hard time posting last night. They kept posting upside down.

How do you post pictures in the post, in between sentences, instead of just at the bottom?


Sent from my iPhone using DO THE TON
« Last Edit: Feb 16, 2019, 20:25:13 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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  • Posts: 1881
    • Lost Apostle
Re: '79 CB750 K
« Reply #4 on: Feb 16, 2019, 20:36:23 »
Dude get an Imgur account if you don't already.  At least that's how I post my images.  Works well, easy to use.  And free.  We like free.  You copy the link that imgur generates (the BBCode) and then just paste it into the body of your text, wherever you want the image to show up.  Job's a good'un.

« Last Edit: Feb 16, 2019, 20:38:05 by The Jimbonaut »
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline Nybz

  • Posts: 31
Re: '79 CB750 K
« Reply #5 on: Feb 18, 2019, 22:20:01 »
Thanks Mr Naut. I will give it a try.

Well a simple way to get out fork seals is just to add more extension for leverage. Came out easy breezy.

It has been difficult trying to paint in a cold damp garage, but I got a system going that I think will work. Anyone got some tips beside hot water heating spray cans, and a little make shift heat booth.

I have been heating the metal before painting with a blow torch and it is amazing how much moisture is held inside the pores of the aluminum. Dripping...Good to get that out before painting I would think.


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 Jimbonaut

  • DTT BOTM WINNER
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  • Posts: 1881
    • Lost Apostle
Re: '79 CB750 K
« Reply #6 on: Feb 18, 2019, 23:00:13 »
Dripping? For real? I had no idea aluminium could hold that much water. I’ll be painting my engine soonish - never thought to heat the engine that much before paint. Maybe I’ll get a heat gun on mine first. Good call.


Sent from my iPhone using DO THE TON
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline Nybz

  • Posts: 31
'79 CB750 K
« Reply #7 on: Feb 19, 2019, 01:08:37 »
Getting the rear hub painted and ready to get put back together.

I used primer, semi gloss caliper paint, and a chemical resistant clear coat. I could have done a better job at taping. I will clean up some lines.

I really debated powder coating parts or not. Especially rims....might regret it. It is just really expensive to take it to a local shop here, for some reason? But I am hoping this paint will do the job with proper prep.

I might pull the trigger on a home powder coating kit from Eastwood for my next project. Cheap enough and would pay for it self quick. Just need figure out 220v out to the garage to put in an oven.


Sent from my iPhone using DO THE TON
« Last Edit: Feb 19, 2019, 01:10:33 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 Nybz

  • Posts: 31
Re: '79 CB750 K
« Reply #8 on: Feb 19, 2019, 01:18:43 »
Here is the front hub.
New spokes, new bearings, retainers, seals.

Threw in some before pictures. Some pretty bad rust to deal with. Lots of sanding....


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 pidjones

  • Posts: 986
Re: '79 CB750 K
« Reply #9 on: Feb 19, 2019, 07:40:22 »
I'm on Tapatalk right now, so can't give the exact process, but there should be a link in the web site version of the forum that says INLINE. Make sure your cursor is where you want the photo, then click place inline (I think you do it after uploading the photo).

BTW, there is a good chance that the water you see dripping off aluminum when heated with an open flame is water condensed from the flame. Best to heat with a heat gun. If you had great results though, carry on!
"Love 'em all.... Let God sort 'em out!"