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The 500's from 89 and up had the same type of cams as that did. But they had a washer that slid on the end of the cam and wedged between the cam's end and the cam cap. There were a few thicknesses I think.
As for why the rythmic clink only every so often and not every rotation of the cam. That's harder to envision but I'll try and explain the way I saw it happening
Imagine the cam bucket was so loose in there that the thing rocked side to side. When the lobe came around and pushed down on the shim and bucket, it would make the bucket rock to one side and as it pushed the bucket down, that made the bucket tip back and then in the middle it would tip to the outside for a second and the whole shim and bucket seemed to have rotated 45 degrees. Then when over center the bucket would shift to the other side and you could see it push the cam as it rotated outward and then let it go once the shim had rotated 90 degrees.
Here's another way of looking at it. Imagine you stuck a feeler gauge in there to measure and then rotated the cam around and got the thing stuck but you only caught the corner of the cam. As you rotate it, only the edge of the cam is hitting the feeler gauge and hitting the shim. As you rotate the cam your actually making the bucket rotate and if the bucket is sloppy and rocks to the side its resulting force wants to push the cam lobe away. And in this case away is towards the side instead of straight up and down.
I think its the rocking motion that gives a resultant force that pushes the cam to one side which causes the clink clink and then let's it go while the cam is not loaded anymore.
And if it was an issue with the chain (as in bent or warped which is possible) you would hear it more randomly or not as often. If for example two links were bent, They would make their way around the sprockets several times before hitting the same place at the right time to push the cam sideways. So they could only be affecting the cam when it wasn't loaded and free to float but the next time it came around the cam could be loaded and not be able to shift over to make that sound.
There was something about this a while back with a 4 cylinder doing the exact same thing. The only fix was new buckets after messing with just about everything else. Even a discussion about making thrust bearings and machining the head to limit the cam walk's travel as a fix.
Easiest thing to try is remove the half moon and use something pointed to push on the center of the cam and see if you can feel it pushing back rhythmically or push harder and make it stop all together.
Could be just one bucket and shim causing it.
Could be dirt under the shim causing this too!!
If you were to take a plain head and put a cam in it and then put the cover on, you can shake it side to side and make this exact noise!
As a matter of fact I was bored one day and measured the sound with a audio analyser while shaking the head. Then compared that to the noise my bike was making. Same frequency clinking.
As for why the rythmic clink only every so often and not every rotation of the cam. That's harder to envision but I'll try and explain the way I saw it happening
Imagine the cam bucket was so loose in there that the thing rocked side to side. When the lobe came around and pushed down on the shim and bucket, it would make the bucket rock to one side and as it pushed the bucket down, that made the bucket tip back and then in the middle it would tip to the outside for a second and the whole shim and bucket seemed to have rotated 45 degrees. Then when over center the bucket would shift to the other side and you could see it push the cam as it rotated outward and then let it go once the shim had rotated 90 degrees.
Here's another way of looking at it. Imagine you stuck a feeler gauge in there to measure and then rotated the cam around and got the thing stuck but you only caught the corner of the cam. As you rotate it, only the edge of the cam is hitting the feeler gauge and hitting the shim. As you rotate the cam your actually making the bucket rotate and if the bucket is sloppy and rocks to the side its resulting force wants to push the cam lobe away. And in this case away is towards the side instead of straight up and down.
I think its the rocking motion that gives a resultant force that pushes the cam to one side which causes the clink clink and then let's it go while the cam is not loaded anymore.
And if it was an issue with the chain (as in bent or warped which is possible) you would hear it more randomly or not as often. If for example two links were bent, They would make their way around the sprockets several times before hitting the same place at the right time to push the cam sideways. So they could only be affecting the cam when it wasn't loaded and free to float but the next time it came around the cam could be loaded and not be able to shift over to make that sound.
There was something about this a while back with a 4 cylinder doing the exact same thing. The only fix was new buckets after messing with just about everything else. Even a discussion about making thrust bearings and machining the head to limit the cam walk's travel as a fix.
Easiest thing to try is remove the half moon and use something pointed to push on the center of the cam and see if you can feel it pushing back rhythmically or push harder and make it stop all together.
Could be just one bucket and shim causing it.
Could be dirt under the shim causing this too!!
If you were to take a plain head and put a cam in it and then put the cover on, you can shake it side to side and make this exact noise!
As a matter of fact I was bored one day and measured the sound with a audio analyser while shaking the head. Then compared that to the noise my bike was making. Same frequency clinking.
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