Author Topic: Mono's '78 CB750K Project  (Read 2480 times)

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Offline mono

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Mono's '78 CB750K Project
« on: November 30, 2012, 08:01:04 am »
Just to keep track of everything, I thought I'd start a thread on this.   this is going to be a SLOW build.

I bought this in September for $50 as a roller with a stuck motor.  All i wanted was the wheels - was planning a wheel swap onto my '81 750C.

After getting it home, i took everything apart and pulled the engine.  Since i had never torn into a motor, i decided "what the hell, it's broken, so i'm not going to break it!" -- threw it on a stand and started ripping into it (following the service manual instructions).  What i found was very surprising.  When i removed the valve cover, i saw no rust.  when i removed the head, i saw no rust... just some slightly carbonized pistons and 2 clean cylinders.  so i shot it all down with PB Blaster, and went and ran some errands for a few hours.  when i came home, i decided to try and hand-turn the crank and after a little groaning i heard a dull "ping!" and she started turning!

So that's the story so far.  currently i have the engine half-disassembled and on a stand.  i still have my 750C project to finish before i really start going on this one, but i do need a mess of parts for the '78 and will be slowly working on it and accumulating parts to form a complete build.

99% sure i'll be cafe'ing this bike.

This is a pic of all the stuff that i got for my $50 investment.  also got the carbs from the seller later on - after i freed up the motor, he dig them out of the scrap pile and gave them to me no charge.  much like the engine, the carbs looked hopeless, but were amazingly clean inside.  2 of the slides were stuck, but freed up in the pine-sol soak i gave them.

Offline mono

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Re: Mono's '78 CB750K Project
« Reply #1 on: November 30, 2012, 08:02:08 am »
the extra 18" rear wheel that he threw in cleaned up really well.  i'm quite sure i'll be using this one -- without the racing slick, of course.

Offline mono

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Re: Mono's '78 CB750K Project
« Reply #2 on: November 30, 2012, 08:11:54 am »
pics of the engine

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Offline mono

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Re: Mono's '78 CB750K Project
« Reply #3 on: November 30, 2012, 08:13:40 am »
Currently polishing the valve cover.  Until I'm done with my other project, I'm trying to minimize the $$ I spend on this bike.  Since there is a ton of cleaning and polishing to be done, it's easy.  Provides a good distraction for when I get fed up working on the 750C.

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« Last Edit: November 30, 2012, 08:17:02 am by mono »

Offline Toxic

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Re: Mono's '78 CB750K Project
« Reply #4 on: November 30, 2012, 08:41:36 am »
Well now that you have some encouraging news on the engine are you going to button it back up or continue with the tear down?

Offline mono

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Re: Mono's '78 CB750K Project
« Reply #5 on: November 30, 2012, 12:24:08 pm »
i'm just going to button it back up until i have the time and money to invest in a full teardown/restore.  the speedo has almost 30K miles on the clock, so i'm thinking that at minimum a good inspection is required.  this will also allow me to blast it and paint it properly, and i'm sure new bearings would be a good idea.   

i figure i might as well do it right if i'm gonna do it.  plus, looking at all the projects here where someone takes the time to tear it down all the way and paint/polish everything.... it just makes me drool.   i'd like this build to be a BOTM-worthy project.  :)

 

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