1977 Honda CB550 K3 re-commissioning
Posted: Tue Aug 01, 2023 7:56 pm
A little bit of background on this one- it is a 1977 Honda CB550 K3, which for anyone who doesn’t already know was sort of the touring-spec CB550 (- the 550F was sold alongside it, it pretty much the same apart from paint and a 4 into 1 exhaust system, but aimed I think at the sportier rider )
Anyway, it was bought by my (slightly) younger brother getting on for 15 years ago on a whim, mainly I think as it was a bike he loved the look of back in his late teens/the twenties (he’s 60 now), but never got around to owning back then, and this particular bike had come up at a local-ish dealer to him at what he thought was a sensible price.
It’s a UK bike with only 13k miles from new, was just about totally original apart from handgrips, tyres, battery, etc and in decent nick as although there was a little degradation of engine paint, etc, the exhausts and tinware were mint, was low mileage and it had no evidence of ever being on its side or “restored”
So back then he bought it, rode it to the golf club once or twice in the first few months of ownership, which was probably 20-30 miles use tops, then it languished in a corner of his garage until a few weeks ago when I went and picked it up with the idea of getting it running again and sold.
I have a bit of a soft spot for 70s and 80s Hondas ( and Yams and Suzukis and Garellis and Fantics and Puchs
), having spent just about every Saturday and school holiday day working for two different bike dealers from the age of 11 until I went off to college, so this was going to be a real trip down memory lane for me.
Oh, and although as I type this, the bike is now just about done and ready for sale, this thread is likely going to be done over a few days/weeks, as there will be a fair few words to type...
Anyway- on with the thread-
On initial inspection, the last 10+ years of standing idle have been kind to – it was in a detached garage with no heating so I was expecting it to be a pile of rust but not so, on pulling it out of his garage, it generally looked pretty good
Immediate issues were that the throttle/carbs had seized solid with no movement at the twistgrip, the front brake was seized on and the lever came back to the bar, and when we turned the fuel tap on, disgusting-smelling petrol ( not unsurprisingly) came straight out of the bottom of the carb overflows.
Oh and one of the (non-standard) handle grips was all manky and rotten
But on the positive side, exhausts all looked as they were 15 years ago, the tank looked sound inside and the tinware/brightwork hadn’t suffered too badly except for an unfortunate sort of stain on the top of the tank that has sort of run down the side, am guessing from some insect or woodland-creature’s excreta, but a bit of T-cut and elbow grease will hopefully sort that
So the first thing once I’d got it on the bench was to get those carbs off, sort the seized throttle issue and leaking carbs- a job I wasn’t particularly relishing as it’s a bit of a pain in the arse getting the carbs on these in and out, ( I take the battery, battery carrier and airbox out rather than fighting with the ( rock hard in this case) carb rubbers and potentially damaging stuff ) and they would of course almost certainly be totally gunged up and require a lot of internal cleaning.
On the positive side though, taking the tank off is a breeze on these with no tools required- flip the seat up, pull the petrol pipe off, pull the rubber back that secures the back of the tank to the frame and it simply slides off- pretty grubby under there, but to be expected, and nothing scary so far
With the carbs on the bench, I started to see the state of them- a bit yucky as expected, and the seized throttle issue was down to the two outer carb slides being gummed/corroded solid in the bodies.
As the job was non-time critical (let’s face it, what’s another few days or weeks when it’s been sitting unloved for the last 10+ years
: ) , I squirted a load of Plus Gas down the carb bodies over a period of a few days in the hope that would do the trick.
It did for No4, but after a week, no1 slide was still well and truly internally welded to the carb body, so out came the blowtorch which did the trick.
Once the slide was free, I could then remove it from the carb and clean it and the internal surface of the carb body up, and all was good.
Although the needles looked surprisingly decent and clean, I’d bought carb overhaul kits which included new ones so they went in.
As for inside the float chambers, pretty horrible as expected ...
I removed all the removable bits and put as much as I could through the ultrasonic bath, and after soaking in carb cleaner, gave all the air and fuel passages a good blow-through with the airline before re-assembling with new top gaskets and float bowl seals, along with new emulsion tubes, main jets, pilot jets, and float needles.
More to follow- getting those carbs back on, oil change (including removing rounded off filter bolt
), setting up ye olde-worlde points/ignition timing, air filter, valve clearances, sorting the brakes,and any electrical issues etc and anything else I find along the way! 
Anyway, it was bought by my (slightly) younger brother getting on for 15 years ago on a whim, mainly I think as it was a bike he loved the look of back in his late teens/the twenties (he’s 60 now), but never got around to owning back then, and this particular bike had come up at a local-ish dealer to him at what he thought was a sensible price.
It’s a UK bike with only 13k miles from new, was just about totally original apart from handgrips, tyres, battery, etc and in decent nick as although there was a little degradation of engine paint, etc, the exhausts and tinware were mint, was low mileage and it had no evidence of ever being on its side or “restored”
So back then he bought it, rode it to the golf club once or twice in the first few months of ownership, which was probably 20-30 miles use tops, then it languished in a corner of his garage until a few weeks ago when I went and picked it up with the idea of getting it running again and sold.
I have a bit of a soft spot for 70s and 80s Hondas ( and Yams and Suzukis and Garellis and Fantics and Puchs
), having spent just about every Saturday and school holiday day working for two different bike dealers from the age of 11 until I went off to college, so this was going to be a real trip down memory lane for me.Oh, and although as I type this, the bike is now just about done and ready for sale, this thread is likely going to be done over a few days/weeks, as there will be a fair few words to type...
Anyway- on with the thread-
On initial inspection, the last 10+ years of standing idle have been kind to – it was in a detached garage with no heating so I was expecting it to be a pile of rust but not so, on pulling it out of his garage, it generally looked pretty good
Immediate issues were that the throttle/carbs had seized solid with no movement at the twistgrip, the front brake was seized on and the lever came back to the bar, and when we turned the fuel tap on, disgusting-smelling petrol ( not unsurprisingly) came straight out of the bottom of the carb overflows.
Oh and one of the (non-standard) handle grips was all manky and rotten
But on the positive side, exhausts all looked as they were 15 years ago, the tank looked sound inside and the tinware/brightwork hadn’t suffered too badly except for an unfortunate sort of stain on the top of the tank that has sort of run down the side, am guessing from some insect or woodland-creature’s excreta, but a bit of T-cut and elbow grease will hopefully sort that
So the first thing once I’d got it on the bench was to get those carbs off, sort the seized throttle issue and leaking carbs- a job I wasn’t particularly relishing as it’s a bit of a pain in the arse getting the carbs on these in and out, ( I take the battery, battery carrier and airbox out rather than fighting with the ( rock hard in this case) carb rubbers and potentially damaging stuff ) and they would of course almost certainly be totally gunged up and require a lot of internal cleaning.
On the positive side though, taking the tank off is a breeze on these with no tools required- flip the seat up, pull the petrol pipe off, pull the rubber back that secures the back of the tank to the frame and it simply slides off- pretty grubby under there, but to be expected, and nothing scary so far
With the carbs on the bench, I started to see the state of them- a bit yucky as expected, and the seized throttle issue was down to the two outer carb slides being gummed/corroded solid in the bodies.
As the job was non-time critical (let’s face it, what’s another few days or weeks when it’s been sitting unloved for the last 10+ years
: ) , I squirted a load of Plus Gas down the carb bodies over a period of a few days in the hope that would do the trick.It did for No4, but after a week, no1 slide was still well and truly internally welded to the carb body, so out came the blowtorch which did the trick.
Once the slide was free, I could then remove it from the carb and clean it and the internal surface of the carb body up, and all was good.
Although the needles looked surprisingly decent and clean, I’d bought carb overhaul kits which included new ones so they went in.
As for inside the float chambers, pretty horrible as expected ...
I removed all the removable bits and put as much as I could through the ultrasonic bath, and after soaking in carb cleaner, gave all the air and fuel passages a good blow-through with the airline before re-assembling with new top gaskets and float bowl seals, along with new emulsion tubes, main jets, pilot jets, and float needles.
More to follow- getting those carbs back on, oil change (including removing rounded off filter bolt
), setting up ye olde-worlde points/ignition timing, air filter, valve clearances, sorting the brakes,and any electrical issues etc and anything else I find along the way! 
) a 1/2" or otherwise slightly smaller socket on there, but that can be messy and not almosts succesful.
) has taken me longer than I thought and I've had enough of sitting in front of a screen and tapping keys , so that's my lot for the moment - more gripping stuff to follow at some point including ignition timing, valve clearances and plugs, maybe even a super-exciting first start (or non-start 
