CB550K - engine rebuild (partial or full)

[Erny]

Certainly I think Charlie's first hand experience out weighs my view, so doesn't appear a big risk.

But through observation of an engine showing oil use I generally seperate as, smoking under acceleration consistently then its normally rings,  with longer run (downhill) with throttle closed,  then emitting smoke just when you open the throttle (single cloud) is ordinarily inlet valve guides as it sucks oil down the valve stems (high vacuum in inlet tract) to be burnt just as you open the carbs again.

Good idea to make a list of concerns that you can then work through later.

This is something I do not know as I'm riding most of the time alone. Even when riding with some mate, nobody reported me any blue smoke behind me, at least not while accelerating.
When having bike on stand, I did not observed blue smoke while playing with trottle.

Estimated oil consupmtion is 0.5-0.7L / 1000km as I do not have it exactly measured. Most oil is burned after longer day-long trips (speed partially over 75-80 mph)

[deltarider]

Nothing to worry about IMO. Realise that the oil 'consumption' you have, may partly due to unnoticed small leakages. The oil drain screw and the shifter seal are notorious for this. After I switched to Castrol GTX High Mileage 15W-40, which is known for keeping the rubbers supple, oil consumption has been reduced.

[Erny]

No small leaks, engine is dry

[K2-K6]

Nothing to worry about IMO. Realise that the oil 'consumption' you have, may partly due to unnoticed small leakages. The oil drain screw and the shifter seal are notorious for this. After I switched to Castrol GTX High Mileage 15W-40, which is known for keeping the rubbers supple, oil consumption has been reduced.

I don't think you'd be able to stand next to it without slipping over if it was leaking 0.5 litre every 1000kms 

At that rate though,  I'd suspect ring and bore sealing  primarily. 

It'll keep the pipes nice inside though 

[Erny]

After long time let me provide short update on this topic.

I was considering several options, first was partial/full rebuild as discussed here (to replace primary chain too), later in order to save season just to fix minimum - valve cover, cam and rocker. For that I bought another cover (new type with 4 non-rotating shafts), megacycle cam 126-00 (for street use) and planned to install it instead of stock one to have better torque. Soon I realised I need slotted sprocket too for proper engine timing etc. (ordered, not arrived yet). Delays were just cummulating
As time was flowing,  new season arrived fast, I decided quicker solution to save this season 2021 - get my original valve cover, camshaft and rocker repaired and install all back as it was till now. So, repairs done  - cover with 2 bronze bushes, worn cam thumb grinded equally and re-nitridated, rocker grinded and re-nitridated. Cam and rocker done by proffesionals, looks like new after that. Of course, cost, don't tell me  we all know...

Along with that I looked closer to carbs (022A, pilot #38, main #100) that since beginning were not perfect (kinda rich, especially 2nd cyl). I found emulsification tubes (especially on cyl#2) are quite worn inside (corrosion), main jets were not Keihin but aftermarket ones). Fixed that with aftermarket tubes (Keyster) and replaced mains by Keihin 100. Bench synced them (stell balls).

Assembled back, all regular service operations done too, all works now, bike idles very well and regular (like never before!), even no need to adjust sync by gauges.
However I observed another unpleasant behaviour, hopefully something I can fix with your support - I'll make new thread for that.

So, for this moment, at least this summer season, rebuild is put on hold, spares are waiting in the shelf 

Bike already tested on the road, I was even photographed 
It again confirmed to me that I love this bike!

[philward]

Glad you are up and running for the summer Erny - great action pictures!

[Laverdaroo]

Great piccies, enjoyed just how they're supposed to be!

[Laverda Dave]

Great photos and lovely looking bike.
Of course you know that now the bike is running just as you like it when the slotted cam wheel arrives it will just sit on the workshop shelf as an expensive ornament

[Erny]

Well, if I will open engine then it will go in. I have never enough power and torque