Topic: My CB750 K1 Build

[KC_Northstar]

        My CB750 K1 Build



I never did get around to doing a build thread during my CB750 K1 restoration, but now
that it’s done I have decided to put something together. 

I bought a CB750 K2 in December 2011.  It was in really great condition with only
18,000 miles, but it didn’t take long to find out that it had lots of engine problems. 
It had low compression in  cylinders 2 and 3 and ran like crap.  I adjusted the valves,
cleaned the carbs and tried to tune it up, but could not get it to run right.  Then it
developed an oil leak that  rivaled the Exxon Valdez.  I realized the only fix was an
engine rebuild.  I probably could have struggled through a rebuild myself, but I wanted
it done right.  I removed the engine and crated it up to be sent off to Hondaman.

I never started out with the intent of doing a complete restoration, but with the engine
out one thing led to another and I was soon off to the races with a complete ground up
Resto.  I also made the decision to restore it as a K1.  I had owned a K1 back in 1972
and had loved that bike.  And so began the long process displayed in the pictures that
follow.

[KC_Northstar]

The Honda parts manual was the most useful, simply because it explains so much
just by looking at all those exploded views.  Hondaman’s book was super helpful
because it explains how to do things in detail that is not present in the CB750 Shop
Manual.   The Clymer manual I could have done without, but because I had it, I used
it to get extra insight on some procedures.  And of course this site provided an
unbelievable amount of info, both by using the search feature and asking questions.
The support of the members of this forum was probably the biggest factor in helping
me complete this project.  Thanks to all the members who contribute to this site.

[KC_Northstar]

Here is how I removed the engine.    I used an 8 foot 2x4 placed on jack stands.  I
attached pieces of 6 inch long 2x4 to each end with screws to keep it stable on the stands. 
I strapped the engine to it using ratcheting tie down straps. The bike was up on
a motorcycle jack I bought from Northern Tool for about $100.
I unbolted the engine and then lowered the bike on the jack about an inch.  I then
moved the bike on the jack slowly to the left.  Engine came out pretty easy using this
method.

[KC_Northstar]

After Hondaman received and disassembled the engine it became clear why it ran so bad.
The PO had installed a high lift cam.  The engine had been over revved and the pistons
on cyl 2 and 3 had hit and bent the intake valves.  The valve lash was improperly set
which had mushroomed the top of the valve stems and one valve spring was broken.  On
top of all that it had a blown head gasket.  The bottom end and tranny were in good shape.
 
The one good thing the PO did was replace the head with a K0 factory ported head.  The
ported head made going with an 836 rebuild only slightly more expensive than a standard
rebuild.  Here are the basic specs for the Hondaman 836 rebuild.

836cc
K1 cam
9.2:1 compression
K0 factory ported head
Mild street port job with polished valves
K0 spark advancer

[KC_Northstar]

Here is a picture of  the newly built engine being test run by Hondaman.

[KC_Northstar]

While Hondaman was working on the engine I completed the disassembly.  Everything
went into plastic bags and was labeled.  I then went through the process of degreasing
and cleaning all the parts.  Most parts cleaned up well using a brass brush wheel on my
bench grinder.



After cleaning the parts, I put them back in the labeled baggies.  I went to the online fiche
parts finder and printed pages of the parts fiche.  I stapled the printed pages to paper
lunch Bags and put all the parts listed on that fiche page into the bag.  Made things really
organized.  When I reassembled the bike I just grabbed the bags for the part of the bike I
was working on and all the parts were right at hand and I had the parts diagram right
there also.  This picture was taken when the bike was about done.  I started out with
a whole lot more bags than pictured.   It sure made reassembly fast and easy.

[KC_Northstar]

I decided to get one of the biggest parts purchase out of the way first.  I ordered a brand
new set of HM300’s from my local Honda dealer.  Turned out to be the luckiest move
I made during this restoration.  A couple months after I bought them they were no
longer available. 

[KC_Northstar]

Sent the frame, swing arm, triple tree and all the other brackets and black painted parts
out to a local company for powder coating.   Turned out real nice and the powder coating
is way tougher that paint.  But even though they did a good job masking the frame, I still
had to run taps through about half of the threaded holes on the frame to clean them up.

[KC_Northstar]

I sent my painted parts to Vintage Honda Painting in Stanton Ca.
.
http://www.vintagehondapainting.com/default.html

Mike did an outstanding job on the Candy Gold paint.








I couldn’t resist putting those nice painted parts on the frame with
The NOS seat to see what it looked like.

[KC_Northstar]

I sent my engine cases and other parts that needed polishing to forum member 73nancy.
Ryan did a great job for a reasonable price. 





The tail light bracket and gauge back plates went to Browns Plating and turned out
super nice.

[KC_Northstar]

I installed bronze swing arm bushings.   I used a threaded rod to press them in.



   

[KC_Northstar]

Here is the steering stem with the All Balls tapered roller bearings installed.
I used the thin spacer.   The thick spacer and the piece of 2 inch plastic pipe were
used to drive the bearing on the shaft.  All those x’s on the thick spacer mean 
“don’t use this one dummy”

I put the steering stem in the freezer and the bearing in the oven at 175 degrees.
That made driving the bearing on much easier.

That plastic pipe also came in handy to seat the front fork seals.  I put the old seal
on top of the new and then the pipe and tapped it in with a hammer.

[KC_Northstar]

Installed new wheel bearings and seals I got from Z1 Enterprizes.

The rims and spokes are Honda OEM.   Took me hours
to get the spokes laced.  Pattern kept coming out wrong,
but I just kept at it till it came out right.

Took the wheels to a local guy they call the "Wheel guy" for truing.




For the tires I wanted the correct vintage look.  I went with a Dunlop K70 for
the rear and Avon Speedmaster for the front.  Both are good tires, but I guess
I’ll find out later how well they handle together.

[KC_Northstar]

I installed the engine in the frame using the same method as removal except in reverse.
Engine went in without a scratch on anything.

[KC_Northstar]

Here are pictures after installing the swing arm and shocks, steering assembly, carbs and airbox.

[rwinn]

Great job! As a new owner of a 78 SS this he's been inspirational. Watching and learning.

[KC_Northstar]

A little farther along   --  front forks, wiring harness and electronic components.

[KC_Northstar]

[KC_Northstar]

  Almost there!   Ready for wheels.

[KC_Northstar]

Wheels on  --  Ready for HM300’s

[KC_Northstar]

    Finished!!

[seanbarney41]

very cool thread with a beautiful bike as the result...just be sure and ride it!

[Opposedsix]

Really beautiful restore

[jerry h]

Really beautiful!!!

I love your idea of printing out parts breakdown and attaching to the bags..... great idea!

Looks like you got the HM's to fit!

Your sure lucky that you bought the pipes early on.

Again,
Very NICE

[deafcaferacer]

Oh man, absolutely beautiful. If it were mine, it'd be on permanent display.