Topic: CB550 Engine Noise (with video)

[Bristledisk]

Hi All, I'm restoring this 1976 CB550K. Still lots of work to do.

I've adjusted the tappets and cam tensioner and ignition and bench sync'd the carbs. The bike starts and idles, all pipes seem equally warm but it's making the following knocking sound.

Any ideas?

[uksparky]

Very loose valve..or worn cam lobe...check valve clearance

[754]

I cant see the video..is it on youtube ... If I had the keywords I could listen.
Is this the motor we warned you may need full rebuild or replace ?

[strynboen]

if it not can hold spec valve adjust for more then a few minuts..the valve shaft have veared oval holes in the cover

..the later modells have fixed that problem,,, bolted The shafts so they not rotate.

.so take the top cover of the engine and look for Lock bolts for the shafts...if there is none...that is your problem

[Bristledisk]

Here is the link to the video from you tube.

This is not the engine where  I was previously advised to get a rebuild. Must be mixing me up with another owner. However having said that may be this motor is just as bad...

[Smudgemo]

If strynboen is correct, you might be able to see the damage by pulling the side covers to the rocker cover.  I had to replace my cover with an updated version because it was obvious that the shaft was round while the part of the cover that held it was ovalized.  I replaced it before I ran the engine, so I can't comment on whether yours sounds the same or not.

[754]

Ok. It was another fellow, his sprocket cover was packed with silt, I suspected a flood bike.

Its pretty loud. Was it quiet on cold startup then got louder as it warmed up ?
 It does sound a bit like it may be lower down.

[firebane]

Ok. It was another fellow, his sprocket cover was packed with silt, I suspected a flood bike.

Its pretty loud. Was it quiet on cold startup then got louder as it warmed up ?
 It does sound a bit like it may be lower down.

LOL that is me. There is like 3 of us working on these bikes.

That rattle does not sound good.

[uksparky]

The noise is half crankshaft speed so it's the top end..Valve area

[BomberMann650]

Those would have to be some serverely damaged rocker shafts to make a noise like that.

[Jimray23]

Check compression on #4

--------------------------------------------------
Jim
1979 kz1000b ltd
    stage 3 cams
    pod air filters
    4-1 open exhaust(no muffler)
    full rewire
    dyna-s ignition
    dyna 3 ohm coils

[TwoTired]

There's probably and exhaust leak in that sound file.

But, the knock is concerning.

Have you a mechanics stethescope or a long screwdriver to press the handle into you ear to probe for the sound source?

[Jzuba550]

Hey,

Wondering if you ever diagnosed the problem with your bike? I am having the same noise in my 74 550

Thanks

[bochnak]

Get rid of the exhaust leak. Use the screwdriver handle to ear trick to locate the tapping.

-Matt