Author Topic: CB750 k4, one for the road less traveled  (Read 1486 times)

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Offline theDQG

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CB750 k4, one for the road less traveled
« on: October 15, 2019, 01:09:37 PM »
The official explanation is that this non-running K4 was an orphan that crawled into the garage one rainy evening to take shelter, and... we just couldn't help it. Of course the live-in girlfriend never once bought that flimsy excuse, but there was no actual resistance, so we took that as a yes-you-may.

What makes this somewhat unusual is that this garage belongs to my friend, a hardcore Harley guy (he has a SG, softtail, and sportser) who has suddenly taken an interest in old Hondas, which you know is sacrilegious in his circle, so his identity shall remain anonymous throughout the course of this build.

I am going to rebuild it keeping the mechanical aspect completely OEM, but upgrading electronics to as modern as possible: M-unit blue, keyless ignition, motogadget everything, antigravity lithium battery, and a PAMCO to boot.

My goal is to take this bike across America on a lengthly road trip- hopefully next spring if circumstances permit.

Obligatory nude:


'83 xv920
'76 xs650
cb750 k4 (2)
'81 R100RS

DQG = The Dumb Question Guy. I ask dumb questions all the time. Bike over ego.

Offline theDQG

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Re: CB750 k4, one for the road less traveled
« Reply #1 on: October 15, 2019, 01:13:00 PM »
Motor out
'83 xv920
'76 xs650
cb750 k4 (2)
'81 R100RS

DQG = The Dumb Question Guy. I ask dumb questions all the time. Bike over ego.

Offline theDQG

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Re: CB750 k4, one for the road less traveled
« Reply #2 on: October 15, 2019, 01:14:34 PM »
Heated up the cylinder gasket, removed four screws under rubber cups, and gently pried apart with wood shims.

'83 xv920
'76 xs650
cb750 k4 (2)
'81 R100RS

DQG = The Dumb Question Guy. I ask dumb questions all the time. Bike over ego.

Offline theDQG

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Re: CB750 k4, one for the road less traveled
« Reply #3 on: October 15, 2019, 01:16:25 PM »
Cylinders off and on the bench. Looks rough on the inside- pic is of #4 cy.
'83 xv920
'76 xs650
cb750 k4 (2)
'81 R100RS

DQG = The Dumb Question Guy. I ask dumb questions all the time. Bike over ego.

Offline theDQG

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Re: CB750 k4, one for the road less traveled
« Reply #4 on: October 15, 2019, 01:17:33 PM »
Looking at the pistons- plenty of carbon.
'83 xv920
'76 xs650
cb750 k4 (2)
'81 R100RS

DQG = The Dumb Question Guy. I ask dumb questions all the time. Bike over ego.

Offline theDQG

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Re: CB750 k4, one for the road less traveled
« Reply #5 on: October 15, 2019, 01:18:59 PM »
Caked valves.. first pic is #1, second #3,#4
'83 xv920
'76 xs650
cb750 k4 (2)
'81 R100RS

DQG = The Dumb Question Guy. I ask dumb questions all the time. Bike over ego.

Offline theDQG

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Re: CB750 k4, one for the road less traveled
« Reply #6 on: October 15, 2019, 01:21:32 PM »
Next weekend we'll be splitting the case. I ordered a set of JIS impact driver bits.

And yes, I have Hondaman's bible, Clymer, plus manual. I'll have to get the parts fiche printout. Think I lost it when I did my other k4.

Everything is going to get vaporblasted, then heads are off to Reick to be ported, etc.

Stay tuned.
« Last Edit: October 15, 2019, 01:26:12 PM by theDQG »
'83 xv920
'76 xs650
cb750 k4 (2)
'81 R100RS

DQG = The Dumb Question Guy. I ask dumb questions all the time. Bike over ego.

Offline RAFster122s

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Re: CB750 k4, one for the road less traveled
« Reply #7 on: October 15, 2019, 01:32:14 PM »
Didn’t Pamco close up shop? Thought I had read in a thread recently that was the case...
Good luck with the rebuild/refresh/modernization!
David- back in the desert SW!

Offline theDQG

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Re: CB750 k4, one for the road less traveled
« Reply #8 on: October 15, 2019, 01:55:52 PM »
Didn’t Pamco close up shop? Thought I had read in a thread recently that was the case...
Good luck with the rebuild/refresh/modernization!

Really? I've been out of the loop for a bit. I'll have to familiarize myself with what's new these days. Been dabbling with Yamahas and BMW's lately- only coming back to Honda just now.
'83 xv920
'76 xs650
cb750 k4 (2)
'81 R100RS

DQG = The Dumb Question Guy. I ask dumb questions all the time. Bike over ego.

Offline Don R

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Re: CB750 k4, one for the road less traveled
« Reply #9 on: October 28, 2019, 09:15:56 PM »
 The Dyna seems to be reliable again and there's always Hondaman's points triggered electronic ignition.
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Offline HondaMan

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Re: CB750 k4, one for the road less traveled
« Reply #10 on: November 09, 2019, 07:18:58 PM »
Caked valves.. first pic is #1, second #3,#4

Looks like #4 intake valve guide is likely toast. I'd sure recommend installing bronze valve guides while it is apart.
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

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Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
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Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

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