Mike's CB550 Project

[Oddjob]

Unlike the front discs ones the rear sprocket ones are quite thick and heavy, they will withstand quite a lot of abuse before requiring changing.

[Mike_Berkshire]

Unlike the front discs ones the rear sprocket ones are quite thick and heavy, they will withstand quite a lot of abuse before requiring changing.

I don’t recall there being any on the front disc when I removed it!

[Oddjob]

There are supposed to be 3 on each disc, they are paired, so 2 nuts on each locking bar, shaped like a bone in essence. Same principle, you lock the retaining disc nut in place so there is no chance of one of the disc bolts coming loose or worse falling out and catching the fork slider, which wouldn't be good 

[Mike_Berkshire]

There are supposed to be 3 on each disc, they are paired, so 2 nuts on each locking bar, shaped like a bone in essence. Same principle, you lock the retaining disc nut in place so there is no chance of one of the disc bolts coming loose or worse falling out and catching the fork slider, which wouldn't be good 

I just checked the shop manual; looks like these were not fitted to the ‘76 K2 which is what I have so I should be good without?

[Johnny4428]

Unlike the front discs ones the rear sprocket ones are quite thick and heavy, they will withstand quite a lot of abuse before requiring changing.

Was thinking of the thinner front disc ones Ken. My mistook.

[Oddjob]

Would depend Mike if they replaced the standard plain nut with shouldered nuts.

[McCabe-Thiele (Ted)]

I guess if you are not sure you have the correct original UBS (Uniform Bearing Stress) nuts?  That's a new term for me. Presumably some sort of  high tensile specification nut, to match the bolts then a lock washer might be a good idea.

[Mike_Berkshire]

They look like the nuts in the picture

[Mike_Berkshire]

I spoke to the guy that is rebuilding my wheels yesterday and they are not going to be done until mid to end of next week so I am still paused. I dont want to run the bike without the wheels on it as I dont have a stable lift; just blocks, centre stand and some old bits of carpet and to further investigate the charging circuit/alternator I need the bike running. So I have been staring at it in the shed thinking of what else I need to do. Apart from the hanging throttle problem the engine seemed to be running fairly sweetly last time I started it. However, I noticed there is a heavy carbon deposit on the plugs and inside the exhaust silencer. Although I ran the bike off the choke after it fired up it hasnt run under load yet. Should I expect to see soot like this if I have just run the bike stationary a few times? From when I first rebuilt the carbs last year I remember the needles are mounted a bit higher than normal and I havent changed the position - I cant remember what notch in the needle the clip is in and I cant find the post I did about this :-(

When I got the bike it had no air filter in it although all the airbox gubbins was in place so this would mean the airflow into the carbs was unrestricted which I assume would mean less vacuum = weaker mixture which may mean the PO raised the needle height in an effort to compensate?? I am running the bike with a new airfilter and new rubber unions from carbs to inlet manifold and carbs to airbox.

If I remember correctly it is possible to change needle height without removing the carbs; is this right and should I reset the needle heights whilst I am waiting for the wheels and the tank is off?

Cheers, Mike

[taysidedragon]

If everything else on the engine is standard I would fit the needle clip in the standard position. I think you're right in thinking that the PO raised the needles to richen the mixture. Put them back where they should be. 👍

[Oddjob]

Flanged nuts Mike, can't use tab washers on flanged nuts, hence why they didn't fit them. Personally I'd prefer plain nuts and the lock nuts in that location.

[McCabe-Thiele (Ted)]

Mike fwiw, my needles are now in the middle position, when I bought the bike it was one groove down, so richer.

I changed the brassware for a good replacement 500 K1 set from Ken, they are 550 carbs on my 500, I also changed the air side screws for the ones that are hollowed out.

[Mike_Berkshire]

Thanks guys. Is it possible to do the needles with the carbs still fitted and what setting/height/groove should I set the needles to?

[Sesman]

Mike.

NUTS. For the avoidance of doubt see the attached…front and rear.

[Sesman]

Yes. I’d start with 2nd groove on 069A carbs. 4th groove if 022A carbs.