CB550K - engine rebuild (partial or full)

[Erny]

Hello all,

Preparing for engine opening and partial or full rebuild. As I’ll do it for the first time, I’d like to kindly ask for forum experts’ advices/recommendations. I’ll keep thread updated as I’ll proceed. Sorry for long post in advance 😉

Bike is stock CB550K K1, has 17.7k miles total. Engine pulls good as far as I can judge (till 70 mph good, above it not so fast, max speed is about 90-100 MPH)

So let’s start with why I plan this and what I want to address/achieve:

1.   Issue with either camshaft or valve rocker or something else – so need to open valve cover as minimum, more details here http://www.sohc.co.uk/index.php/topic,23227.msg208693.html#msg208693. Along with that I want to replace valve cover by new type, that have fixed rocker arm shafts. But need to find it first. Along with that of course new gasket.. Optionally, if it turns out that camshaft needs to be replaced, I’ll try to find one with improved torque or one from CB650. And of course rockers if replacement needed

2.   Rattling noise @idle coming from head-cylinders (pushing clutch makes just little difference). I’ll make video and post it here, maybe you know that noise and its route cause. Bike idles well, ign. set properly, carbs synced

3.   Cam chain replacement

4.   If head will come off – complete head work – cleaning, valve checks, eventually new valve guides, seals, check for flatness / milling … simply taking opportunity that head is off, check/replace all needed. All gaskets / O-ring / seals replacement. Check/replacement of tensioner

5.   If cylinders will come off – replacement of piston rings. I expect bores & pistons will be OK

6.   Splitting cases is big question now – I’d like to fix shifting issue, but still hope this could be caused by mechanism under clutch (?) http://www.sohc.co.uk/index.php/topic,19775.msg175185.html#msg175185 On the other hand side, having cylinders off, maybe it is good idea to replace all seals, primary chain and check gearbox (?)

Now first questions – before I pull engine and start stripping, any advice what I should do before?

I’m thinking about:
-   leak test (to estimate rings / head status to be confirmed when removed)
-   redo compression test to have reference for comparison after rebuild. Last measurement was: dry: 120/120/110/130 psi, wet (teaspoon oil into each cylinder) : 150/150/145/145 psi
-   detailed inspection of clutch and shifting mechanism under basket – maybe after that case splitting not necessary (?)

Any thoughts / ideas / advices what else I should do before pulling engine / stripping?

[philward]

I think you seem to be 'on it' Erny! Hard to comment until you start the strip

[Nurse Julie]

I will watch with interest Erny.

[Bryanj]

IF you have the motor stripped to base gasket and clutch cover off and you say you are thinking about a primary chain as well as cam chain dont forget the cush drive rubbers in the primary hub, not cheap for a full set but needed if primary chain being done. NOTE:- the 550 casing are slightly diferent castings and the primary can be way more worn than the 500 before it wears the oil gallery

[Erny]

I will watch with interest Erny.

thanks Julie, I hope Trigger will give some advice 

[Nurse Julie]

I will watch with interest Erny.

thanks Julie, I hope Trigger will give some advice 

I'm sure he will Erny.

[paul G]

I will watch with interest Erny.

thanks Julie, I hope Trigger will give some advice 

I'm sure he will Erny.

[deltarider]

Bike is stock CB550K K1, has 17.7k miles total.

To me the operation sounds a bit premature. These bikes were considered not to be fully broken in before one had 10.000 km on the odometer. Yours has 17.7k miles only.
When I had opened mine in 1987 and taken the engine to a mechanic for the measuring etc., first thing he said, was: why did you open it? I had no clear answer and I hesitated to tell him that at around 40.000km, I already had the camchain and tensioner renewed. Now, at around 80.000 kms - I had guessed - it would be about time again. I mean, what did I know? And let me also confess an amateur like me, had felt it a challenge to open up the engine, out of curiosity, just by following instructions the Haynes manual gave me. Not that that particular manual proved very helpful as it doesn't even cover the four rocker arm shafts lay out my model has. BTW, there are plenty that never had a problem with the eight shafts and to my surprise they are even found on the CB550K2 (76) up to engine number 1083640!
The mechanic commented he had seen CB500s that had done much more kms before an overhaul. I had taken the engine to him because he had a good reputation, had been a Hondadealer for decades and I didn't want to invest in measuring tools etc. anyway. Tools I'd probably use only once in my life. Also... a small sticker on the rear fender indicated the bike was first sold by his business in 1977. He had seen quite a few CB500s that had done 150.000 kms with just prescribed maintenance. BTW, in my archive, I have an article about a guy who had bought his CB500 new, rode it daily (summer and winter) and at the time of the article had done 220.000kms in 20 years with just the sceduled regular maintenance.
Anyway, here are the parts that were replaced: pistons (standard size) including pins and rings. Gasket set. Camchain and tensioner. Two rocker arms. Four exhaust tappets and their guides. Four spark plugs. I don't know if all these replacements had been necessary, meaning they were at their minimum. I don't rule out he had calculated that now the engine was open, it was a sensible thing to do in advance. I collected the engine, fitted it in the frame again. Now did I experience much difference? Mwah, not much more than before when I had renewed the spark pliugs. This is to warn you to have modest expectations about the outcome. We seem programmed this way: if I do this or as soon as I've bought that, things will be much better. In other words: somehow we are programmed to project an ideal outcome. So, I don't know if you know an oldtimer that has seen a lot of these bikes in his career as a mechanic. I'd ask him for a second opinion.
About the clutch. Although yours is different from mine, they're easy to work on. By the time I had to renew my clutch friction plates and springs, they had exactly reached the minimum Honda specifies in the Service Data chapter in the Shop Manual.
Why the CB550Ks have been not as fast as the CB500s, I don't know. My guess is increased weight and a different gearing have to do with it. All CB500/550s however should manage a top speed of 160 km/h+. On the Dyno mine reached 185km/h, but that was without winddrag ofcourse.
I now have 40 years of experience with my bike. Here a few things I have learned. 1) Plugcaps and leads are always the first to be suspected. 2) Our bikes don't particularly like nowadays gasoline. Years ago I used a fuel system cleaner (Tunap) for the first time. The result was phenomenal. It felt like the engine was reborn. And there was this nice rustle again I had dearly missed for so long. I'm still in the process of finding out what 'maintenance dose' of what is best.
A lot has been posted about engine oil. I prefer an oil that sticks to the camshaft somewhat (better for cold starts) over superduper full synthetic oil that will simply return a 100% to the crankcase, once the engine is stopped. The oil I use is not specific a 'motorcycle oil' whatever that may be. For a JASO oil the weight percentage of sulphate ash should be 1,2% maximum. That 1,2% happens to be exactly what Castrol specifies for the oil I use and since I have never experienced a slipping clutch, I see no problem in continuing to use that oil. I don't worry about the engine. I am quite tall and have therefore pulled the rubbers from the footrests to have a slightly better riding position. After all these years I still feel no vibrations there whatsoever. Not more than 40 years ago.
If you allow me a question. Like mine, yours has the beautiful 4-4 exhausts. I'm still not content about the way I have fitted them (left side). Sohron and Ashimoto have helped me a lot with their directions. Right side seems to be OK. Although... I still wonder, should the ten bolts that hold the oilpan all be accessible for a straight pipe wrench? Can you have a look what the situation is at yours?
Oh, I almost forgot. Make a good sound recording of your engine running, post it and let the experts here comment.

[Erny]

For Delta: on my 550K1 oil pan bolts are fully accessible on the left, on the right bit less, but still accessible see pics (on 2 pics I put ruler to show approx distances

[deltarider]

Thanks, Erny. I have more or less the same situation. As it is now, right side bolts are less accessible. On the left side, #2 pipe is touching the sidestand bracket which I don't like. In my case it has to do with the rear brackets now being both on the outside of the frame eye. According to Sohron #1 rear bracket should be on the outside, #2 on the inside of the frame eye. So... looks like I still have some tweaking to do.
I can not for the world remember, how it was when I first acquired the bike and I still wonder if bikes left the assembly line with all ten oil pan bolts perfectly accessible. Let me say that I have my doubts. Maybe others will chime in.

[K2-K6]

One thing that I feel helps, I use a Bahco 1/4 drive socket set that has not only really good quality six sided sockets,  but also a very good angular drive extension bar ( barrel shaped drive cube) which allows just enough displacement to get onto bolts without having to use a drive knuckle.

Obviously doesn't comment on exhaust alignment,  but useful nonetheless.

[deltarider]

Thanks K2-K6. I have no plans removing forsaid oilpan. I have done it maybe two or three times since 1980 and it always proved very clean in there. Have a look at the screenfilter the last time I opened the pan. I didn't even bother to clean it. The oilpan dito. I have also done it twice on my yacht. Same result. I was just curious Honda's strive for perfection back then had gone so far that - with the exhausts hung as it should - all ten bolts were accessible for s straight pipe wrench. I doubt it.

[Trigger]

Loosen the nuts off on the down pipes and the rear mounting bolt , and the pipes will move enough to get a T bar in or a 3/8 drive 

[Erny]

to steer back to my topic (if you allow me  ):

Please somebody to advice on my first questions – before I pull engine and start stripping, any advice what I should do before? (Trigger maybe?)

I’m thinking about:
-   leak test (to estimate rings / head status to be confirmed when removed)
-   redo compression test to have reference for comparison after rebuild. Last measurement was: dry: 120/120/110/130 psi, wet (teaspoon oil into each cylinder) : 150/150/145/145 psi
-   detailed inspection of clutch and shifting mechanism under basket – maybe after that case splitting not necessary (?)

Any thoughts / ideas / advices what else I should do before pulling engine / stripping?

To provide more about current engine "noise" at idle - here is short video I made today https://youtu.be/9CKtENPWWDY, interested for your comments

[Bryanj]

Sonds like you need to inspect pistons and rings BUT a hot compression test is best, if you can get 135/140 when hot i would leave it alone.
Top end can be done with engine in, apart from that every time you open a can you find more worms