New CB550 1978 Project

[Nimmy9]

Hi all.

I have been a member for a while, previously when I was doing a light restoration on a CB400/4 which went OK was fun to ride but then I sold it on as I wasn't making much use of it.  I also found full-time work got in the way of playing with toys.
After 42 and a bit years of work, I am now released from such drudgery and can start doing these other things to keep me out of the missus hair!
Having owned a 550 many years ago (early '80s) I thought I would try my hand at another light restoration initially so I have picked up a US import K4 1977 build, 1978 MY in Excel Black.  Cosmetically it is better than I thought it would be - but like all of these has its issues.
1.  Clutch sticking - takes quite a heavy hand to move the lever
2. Nothing from back of carbs under seat - ie empty space.  So I will need the air filter system and battery tray etc
3.  Seat will need recovering and hinge pins
4. Looks like an after-market cruise control added to the throttle grip
5. Throttle and choke cables disconnected.
6.  carbs stuck so will get those off and clean them up.  Until then can't try starting her up and listening to the engine.
7.  Brakes binding and front needs complete replacement.
Otherwise chrome is all good, paintwork decent, and engine clean and turns over and all gears select.  I wonder if US owner was looking at modifying to air filter pods??
Not afraid of the work, but would like some advice on where I can find the bits I need (including new throttle controls), so I can get on with it.
Originally I was looking at doing some form of conversion, but overall this bike is pretty decent I am thinking of getting it cleaned up and running and using for a while, and then a more serious 500/550 project later.
I have been riding since 1971 with various bikes maintained myself of all sorts from old British, Harleys, and currently a BMW R1200RS for serious touring.
Any help thoughts or advice welcome.  I have been reading the site regularly and have already got some useful tips and links so thanks for that.

[hairygit]

Agggh! PD carbs! Chances are the U.S. owner had trouble with them and removed the airbox etc to make it easier to keep taking the carbs off Best thing to do is look for an earlier set of carbs, as they are a lot less trouble to work on and use.

Sent from my X6pro using Tapatalk

[Nimmy9]

Thanks Hairygit.

Which ones work best and anyone got any?  What happens to the recycle gases pipe that I understand comes out of the head of the engine, through the filter and then back into the carbs? - or does it by-pass the carbs?

Incidentally I found the original owners manual under the seat with some notes of oil changes handily written on the back page!!

[Nimmy9]

Whoops - just found the diagram and it comes back in via the filter so no real issue (I hope).
Just connected a good battery and all electrics work apart from the horn 

Frame no CB550 - 2109568
Engine.    CB550E - 2109842

[hairygit]

Yes, the idea behind the recycle pipe is that any unburnt hydrocarbons are recycled via the air filter, into the caebs from the filter and fed back into the engine, a very primitive form of emission control. Works okay, but if the engine is worn/burning a bit of oil, it rather quickly makes the (very expensive!) air filter wet with oil, and restricts the air flow through it, which makes the engine run rich (like having the choke part on all the time) which in turn causes more wear to the rings by excess fuel washing the oil away from the bores. What a lot of people do is run the pipe from the engine to atmosphere, usually down behind the engine, making sure the pipe can't spit oil onto the back tyre.

[Piki]

Agggh! PD carbs! Chances are the U.S. owner had trouble with them and removed the airbox etc to make it easier to keep taking the carbs off Best thing to do is look for an earlier set of carbs, as they are a lot less trouble to work on and use.

Sent from my X6pro using Tapatalk

Yes, I have fits on my 550 k3 a 550 F carbs, PD carbs ara a nightmare to set and adjust.

[Piki]

Hi all.

I have been a member for a while, previously when I was doing a light restoration on a CB400/4 which went OK was fun to ride but then I sold it on as I wasn't making much use of it.  I also found full-time work got in the way of playing with toys.
After 42 and a bit years of work, I am now released from such drudgery and can start doing these other things to keep me out of the missus hair!
Having owned a 550 many years ago (early '80s) I thought I would try my hand at another light restoration initially so I have picked up a US import K4 1977 build, 1978 MY in Excel Black.  Cosmetically it is better than I thought it would be - but like all of these has its issues.
1.  Clutch sticking - takes quite a heavy hand to move the lever
2. Nothing from back of carbs under seat - ie empty space.  So I will need the air filter system and battery tray etc
3.  Seat will need recovering and hinge pins
4. Looks like an after-market cruise control added to the throttle grip
5. Throttle and choke cables disconnected.
6.  carbs stuck so will get those off and clean them up.  Until then can't try starting her up and listening to the engine.
7.  Brakes binding and front needs complete replacement.
Otherwise chrome is all good, paintwork decent, and engine clean and turns over and all gears select.  I wonder if US owner was looking at modifying to air filter pods??
Not afraid of the work, but would like some advice on where I can find the bits I need (including new throttle controls), so I can get on with it.
Originally I was looking at doing some form of conversion, but overall this bike is pretty decent I am thinking of getting it cleaned up and running and using for a while, and then a more serious 500/550 project later.
I have been riding since 1971 with various bikes maintained myself of all sorts from old British, Harleys, and currently a BMW R1200RS for serious touring.
Any help thoughts or advice welcome.  I have been reading the site regularly and have already got some useful tips and links so thanks for that.

Looks great your bike, good buy!!

[Seabeowner]

Well welcome (back) Nimmy9. Very strange a new member joined last week zebedee and has a 550f in shiny orange and then you come with a 78K. I have both. Both are US imports that I bought at the back end of 2015 The orange F is back and registered. The 78 is still in bits.
Indeed I believe the K3, K(4) carbs appear to be a handful, but I'm going to stick with it even though I have a spare full set of the earlier carbs. Spent a week last year before I stripped the bike cleaning and ultrasonic cleaning the carbs and made no difference at all! Another reason to replace carbs with the earlier ones is that the inlet rubber connectors between airbox and filter box assy are longer on K3, K4 and quality examples unobtainable.
Mine 78 had a slipping starter clutch, which I managed without splitting the engine, but most of the rest of the work has been cosmetic and sourcing (quite) a few missing (and expensive) bits.
Yours looks a much better example than mine though.  Good luck.

[Nimmy9]

Thanks Seabeowner.

I think I will fully refurbish these carbs anyway so that I have something usable while waiting for an earlier set.  Just pulled them off and took off the float chamber covers - no floats at all inside!!  I shall order a full refurb kit.

Anyone any ideas why the clutch lever should be so difficult to move??

[hairygit]

Floats don't come with a refurb kit, you'll need to source those separately. You get float valves in the kit.

Sent from my X6pro using Tapatalk

[kevski]

There is nothing wrong with these carbs that regular use a fuel stabilizer and setting up properly won't take care of, I run a K3 for years and only set it it up once when I first got it, all this nonsense about difficulties is tosh.

[Nimmy9]

Hmm. opinions, opinions!!

Anyway, does anyone know where I can get floats and what keeps them in place, a battery tray, and all the gubbins for the air filter??

thanks - I do love this forum and the people who make it such fun!!

[Norniron]

If u do convert to the earlier carbs you're gonna need the inlet manifolds to suit.
It is as Hairygit says a worthwile mod as from experience those later carbs are a nightmare.
But hey ho your bike your rules

[matthewmosse]

I have mixed experiences with the k3 carbs, I have indeed had problems with a set, but my first big bike was a cb550k3 with those carbs and it had better economy and was pretty damn reliable in that respect, carbs never played up until the bike was parked up for a few years. The extra economy proved very handy if riding in remote areas as an extra 20 miles or more in the tank saves on fuel fill up paranoia, by me if you head on some trips you can cover 80 or 90 miles between petrol stations after 7pm. That extra range can be handy as well as saving cash. I vaguely recall buying a set of carbs for spares, might have the bits you are missing though I might not have time to look til weekend and they might be the other type as I have both cb550k3 and cb500 bikes. Its a long shot but there might be most of a air cleaner spare too....

[Nimmy9]

Thanks Matthewmosse
I would like to hear if you do have anything that might help