1976 CB500K2...

[ST1100]

So, today's work unit started with a pile of parts from two carb banks...
Did some detailing with carb body cleaner, gasket remover and a small brush, another rinse, washing down with brake cleaner and blowing out every bore and channel.
Then scrambled the most useful looking items for building my test carbs.
Quite some work, sliders got new needles, all linkage points (springs, pans, ball-joints) a tiny dab of BelRay marine grease (probably the first lubrication they saw again since leaving the factory...), choke axle & lever on #1 required removal and adjustment (bend handle...), a few drops of engine oil on the surfaces of the sliders prior installation, same on the axles of the choke flaps.
The actuators, washers, springs, spacers, felt rings, etc... all cleaned and lubed before installing them.
Did a "bench sync" by using the shaft of a 3mm drill-bit as feeler-gauge, all is moving smooth and effortless again now.
Started to install jets and nozzles, to ensure damage free fitment all O-rings got a tiny dab of silicone grease smeared on...
Will have completed that tomorrow, and probably try to start the engine then...

The quality of the materials used by Honda keeps astonishing me... 4 decades of neglect and abuse, just clean and adjust, fully operational again...
Like the top covers and bowls, a little rub with a tiny dab of Autosol (probably spit would have served just as well  ), a brief buff with a soft cloth and suddenly you've got bling on the bike 
Seems a genuine Honda doesn't break by itself, it requires ignorant people to ruin it...  (except those build in Atessa which already rusted away while still in the showroom, but that was a different story anyway...)

[AshimotoK0]

sound likeyou are getting stuck in ST

[ST1100]

Occupational hazard I guess... and respect for the ingenuity of those bikes...
Also my ST1100's always receive that aviation-like attention to details... pays off when you're abroad for two weeks, far from home, like somewhere up north in Scotland or deep in the south of France... the rig never let me down... the least you want is a spoiled ride/vacation over some neglect...

[ST1100]

... ITS AAALIIIIIIIVVVVVVVEHHH!!! ... 

But, first things fist...

Tinkering with the bits 'n pieces...

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Planning to use jubilee-clips for air-box rubbers or holding those fancy pods?
Please don't... 

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...a real PITA to straighten those dents again 
the MFG designed those steel bands for a reason...

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A little before and after comparison

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[ST1100]

all pretty much set up

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Note the different gasket-groove on the carb bowls from different sets.
LHS features small grabbing-bulges enabling the use of O-ring type gaskets as delivered with the Keyster sets,
RHS (probably earlier years??) instead do require the pre-shaped seals

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All buttoned up, ready to be thrown at the bike

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I did not want to use any new bolts at first, but all the old ones are so corroded and rounded off, I just didn't have the heart at the end... 

[ST1100]

Had a wrestle with those new carb rubbers of course...
Having a heat-gun, priceless... 

Those refurbed carbs do look a bit out of place on that old beaten up motorcycle

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Weird setup with that infusion bottle thing dangling from the ceiling
Need to get me a proper IV-pole ASAP...

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One of those vintage SUN-monitors aside would really make a statement in that assemble 

[ST1100]

Of course is there no such thing as easy...

#1 tended to overflow... fixed...
#4 didn't want to fill at all... fixed that to...
Fortunately only the two outboard carbs were acting out... yes, it is possible fixing that with the bank on the bike 

Attached and adjusted the throttle cables... working as one can expect with the old switch-pod and grip on...

So, we've oil topped up and instant oil pressure within two starter revolutions, which is a good sign of some sort...

We've reworked carbs and fuel in them...

OK, choke working nicely, set to about 1/2, throttle closed...


To be honest, I didn't really expect what happened next...

Careful me I never operate a starter motor longer then like 3~5 seconds...

...vieeee-vieeee-vieeee...

...vieeee-vieeee-vieeee...

...vieeVRRROOOOOOOOOOOOOOOOMMMMMMMM....

WTF just happened??!!!!

40 years of sooth, rust, abuse and neglect belching out that tulip-endpipes, stinking up the place within seconds with the engine screaming to life at steady 3000RPM... 

Stunned I hit the kill-switch and ran to kick them doors open...

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...couch-couch... 

Can this really be???
Confused I'm switching back to RUN and blip the starter button:

...vieeVROOOOOOOOMMMM...

Yes, it runs!
No knocking, no clatter, no abnormal noises... I'm flabbergasted...
I reach near the downpipes, and indeed all 4 emit heat into the palm of my hand...
I walk around the bike, no oil or other liquids pouring out...
Moving the choke to off I get brave, trying to gently work the throttle... vrooom-vrooom-vrooom... carefully avoiding going higher then ~4000rpm yet... blizzards of rust bits flying out the end-pipes, but hey it likes that, it want's to go! Smooth... 
Any spectators around would need to wear respirators and ear-muffs though... 

What a persistant little motorsickle... grounded and neglected for I don't know how long, flawlessly firing up at the 3rd push already?!... un_F_believeable!!! I think I'm finally smitten...
I'm familiar with such reliability from the V-4 plants in the ST1100, but those engines are from the 90ies and a V... not a line-4 from the 70ies...

Since I couldn't get the idle lower then ~2500rpm in a quick way (will deal with that in a second work-run on them carbs), I stopped the engine after aprox 5 minutes to let the now warmed oil drain (an what a black sludge that was...  ).
Them PO also hadn't used a crush-washer on the drain bolt, so it was torqued hard but came off without damages...

While that "tar" drained I broke out the shop-vac (big ass Hoover for you  ) to clean up the mess that starting incident left all over the place...

Once the house was clean, I closed the doors to keep the winter cold out and focused on the CB again...

Bad news: that oil filter bolt just won't bulge, it was already rounded and slightly damaged so I refrained from applying any further excessive forces, will deal with that later, probably need to cut it off or have a go with the impact-wrench, unless you guys have any good tips there...

Anyway, new 10W40 went in, to ready it for the next test run...
I'll remove and rework them carbs again (ridiculous if they couldn't be brought back into full working condition, damn...), check/adjust the valve clearances once more and once I can establish a proper 900~1100rpm idle, I'll check mixture and sync...
And once the engine has belched, coughed and spit out most of them cobwebs and deposits, I'll have another look at the compression to decide where to go from there.

And, note to myself: the next test run happens outdoors... 

[Green1]

You should have known it would run its a Honda after all.
Plenty of heat on the stubborn filter bolt should free it.Don't forget to put the spring back in when you do free it.I forgot to put it in mine twice.

[ST1100]

You should have known it would run its a Honda after all.

Yep, got that right... should have known better 
Thanx for the tip, planning to have a go with the blowtorch later on, during the next oil change (want to flush the case as good as possible).

Dunno yet if I've should break the engine open or not...
If it runs smoothly and shows proper compression?
Maybe I do just the top-end, overhaul the head, new timing chain, tensioners...
What's the general view there? It has done 40.000km... how durable are those engines?
SC26 plants will easily last 400~500.000km, with proper maintenance provided though...

[Green1]

My green k1 had 70k on the clock and showed excellent compression that had also stood for years.
I should change the timing chain really I suppose
Its still running perfect at 80k and it gets pushed at times
I have a rule if it runs it runs if it did it in the 70's it will do it today.

[ST1100]

Its also my opinion that a factory build engine won't grow any better by someone (me) knocking it apart...
Just treat and handle properly, apply care when servicing and address any issues prompt and accordingly.

[Bryanj]

If it wont tick over and the idle screw is unadjusted all the way plus play on the cable  chances are that you have got the adjusters screwed in so much that the slides are "Hanging" on the adjusters.

To get the filter bolt out its either a 3/16 or 1/4 Whitworth socket that is a "Hammer Fit" on the bolt head

[matthewmosse]

My cb500/4  got to 170 000 miles before I had any reason to go inside the engine. Even then the primary chain hadn't taken lumps out of the crankcase or anything sinister, only issue was she would not stay in 1st or second under load. My own view is that if you can attain that kind of milage with little more than oil changes then taking a healthy engine appart is a waste of time and gasketts. On the other hand I have had other sohc 550's where the inside of the engine has been in a very bad way at 30k miles, these have inevitablynsuffered from rebuilds by beginners before I got to them. My rule of thumb, if it looks good, sounds good and runs good leave alone. If there are any sighns of gaskett goo owning previous owners, then have the rocker cover off, check oil supply to top end, then play it by ear from there.
regards oil filter bolt, set of stilsons / pipe wrench has often proved effective for me.

[ST1100]

...chances are that you have got the adjusters screwed in so much that the slides are "Hanging" on the adjusters...

Since idle screws are set properly to 1+1/8th turn out, also my theory that I simply overlooked having the slides resting on the bottom of the bodies with no tension on idle adjuster, belly-crank or cable...
But since also the floats are acting up a little, I'll have to make a do over anyway... considering their original condition I actually didn't expect getting them to work perfectly right away... 

So, the plan is
a) get them carbs working properly
b) check valve clearances again (rust & deposits might have worked off)
c) sync and adjust to a nice, smooth idle/tick-over
d) shift through the gears with the bike secured(!) on its main-stand (no working brakes yet...) with the rear wheel spinning as load
e) remove breather cover for inspection
f) have another compression test

If nothing serious appears, I could then dump the oil again and remove that filter case before dropping the engine out the frame for restoration processes...

[ST1100]

Not much new yet...
Parcels keep arriving: new oil bolt, new (NOS!) air-filter housing (essential as the old one was drilled, thus provide altered air-restriction), a set of new coils (pattern parts though...)...