Topic: 550 power issues, oil seap

[junkyalleycat]

Hey Guys,

There are a few things going on with my 550 currently.  The cam chain is rattling an unhealthy amount, there is something of an oil leak coming from one or two of the cylinders and there is also a power issue coming out of idle.

The cam chain needs to be replaced, and so for that I am getting a new cam chain, and a soft link.  I figure that the oil leak may be old gaskets leaking, and so I also got a new gasket and o-ring kit, as well as a new set of piston rings for all of the pistons.

The thing that I don't understand is the power issue.  The carburetors were just cleaned, and the timing and valvers were just adjusted.  The issue is that accelerating from an idle causes the engine to misfire and stutter for a second before it catches.  This only happens after riding the bike for about fifteen minutes from a cold start.  This stutter also happens sometimes in accelerating in higher gears.  Could this be a compression issue caused by leaks in the gaskets?  I was thinking that maybe oil was plugging holes when the bike is cold started, and that the oil is displaced during the ride, make for bad vacuums.

I haven't taken the temperature of the cylinders after a ride yet, so I'm not sure if they are all working equally.  I think the power problem will be easier to localize once the cam chain and gaskets have been replaced, and possibly even solved by doing so.  Is there anything else that I should look for or possibly replace while I have the top half of the engine off?  Any ideas what the power issue may be?

Thanks!

[OneWheelDrive]

Wow, that raises many questions:

What makes you think that the cam chain needs to be replaced?  The bike will make quite a racket if the carbs are not synched properly.  Have the carbs been synchronized using a vacuum gauge?

What is your intake and exhaust setup?  Stock airbox? 4 into 4 exhaust? custom 4 into 1 header? 

What are the jets in the carbs both pilot and main? 

Have you performed a plug chop when the bike stumbles?  If you inspect your plugs immediately following your symptom, you could see if one cylinder (or many) are running lean or rich.

Have you performed a compression test?

Have you tried re-torquing the head to spec?  This could solve the weepy head problem.

I know the search function is broken, but use the google search bar to find details on what I've suggested. 

[TwoTired]

Rare, a cam chain wears out.  Have you verified the chain tensioner operation/adjustment setting?  All the noise will never go away, as the chain slides upon a shoe.  But, the tensioner cures most of it.

The 550 will weep oil with age and never come close to losing a compression seal.
The oil passage flows up through the each end of the cylinder block.  At the head interface are two orings that deteriorate from heat and lose their seal.  It is rare that they lose enough oil to effect operation or reliability.  It's usually just an annoyance.

The other common oil leakage come from 6 rubber disks that seal cam cover to cylinder head.  These, too, harden and loose their sealing ability.  But they can be replace during a cam cover removal operation, without disturbing the head.  (Do heed the shop manual warnings about cam cover installation, unless you are happy buying new valves and/or head for the motor.)

I can't understand why you would replace piston rings that are providing good seal, with new ones that won't seal until after a break in cycle that removes metal form both cylinder walls and the new rings.

The acceleration "stutter" may be a false perception or a real carburetion issue.

What carbs are you using?  What are their settings/jetting?
Do you have an air filter, what type, and how old?
Do you have stock exhaust?

Are you expecting to snap open the carb slides from idle and get smooth acceleration?

Have you got the Honda shop manual for your bike?

Do we assume your questions pertain to a totally stock 1976 CB550K model?

Cheers,

[Duanob]

junkalleycat what part of seattle are you? I'm in west seattle same with member brainzenk. Post a pic of your bike around the areas of the ouil leaks. It is probably the usual leaks that these engines have and hopefully not too bad. I recently replaced my head gasket with new oil gallery o-rings. These o-rings dry out and crack when the bikes don't get used. It's not critical unless you are spewing oil. I replaced my head gasket a year ago and the leak came back, this last time I used an OEM honda gasket and o-rings and sprayed copper coat sealer on the gasket and so far so good, no leaks.

Cam chain to tighten is counter clock wise but don't use a lot of force when tightening the tensioner screw. You can do it while it's running. If the carbs are out of wack that will cause your primary chain to rattle around that could be what you're hearing. A vac sync will help.

You say the carbs were cleaned and timing and valves set but by who? Did you take it to a shop? If so which one? Frankly I feel jerked around by all the shops around here so I learned to do everything myself. Get a manual and stay tuned to this board and you can too.

[junkyalleycat]

Hey Guys, thanks for the responses.

The bike is a stock '76 550 K2, except for the muffler 4 into 1.

Duanob, I'm in Central District.  I brought the bike to twin line for an initial tune up.  Being my first bike, and first engine, I thought it would be good to have a nice baseline to work with before I tried working on it myself.  The difference was like night and day, though there was still the outstanding issue of the cam chain that they warned me about.  The issue specifically was that it was warn and not adjusting properly anymore, so should be replaced.  If they were to fix that too, the bike would have had to stay in the shop for a lot longer.  Because of the cam chain, they also were not able to do a completely proper job on the vacuum sync.

I followed the instructions in the clymer to properly adjust the cam chain tensioner.  I didn't use any force on the screw though, as I thought that the piece was supposed to adjust itself without force.  After I did this (with the overhead at TDC) the sound of the chain got a lot better, thought it still rattles more than I think it should.

I'm beginning to think that maybe the power issue I'm speaking of might be me being too aggressive on the throttle.  I've noticed that I don't have a problem when I apply the throttle more slowly.

The picture below shows the points where I believe oil is leaking.  The reason I believe it is from these two spots is because I can see when the bike is running a line of "activity" about these seals.  Activity meaning some small bubbles and liquid movement.  Oil is not currently coming from them like it was though.  A week ago there would be oil residue on the cooling fins on this side of the bike, but that residue has dried and not returned.  I have checked the oil level multiple times and it reads good, just below the top line.



Thanks again for the replies guys, this site is a great and sometimes overwhelming source of information

[TwoTired]

Those inspection caps have a rubber oring.  If they are 40 years old, the rubber may not be what once was.  Go for the easy stuff first.  Replace the orings.  Further, if those inspection caps have been over torqued, they will crack and then leak at the crack.

[dave500]

use a six side 17mm socket on those caps,see if you can grind the socket so it has no entrance ramps like in this photo ,a cheap socket is ideal for this,only just nip them up aswell.
the left socket has been ground,no ramps,the right socket has ramps,this type only gives say 50% bite on that slim hex and youll round it off easier.