RGS 1000/120 cam wear

[parrishsteve]

Hi,
As I was checking/adjusting valve clearance I noticed 2 oddities with the exhaust cam and cap/bearings. Take a look at the pics. One pic shows the middle cam cap. Note the grooves in the aluminum cap, they are deep enough to feel them with your finger nail, however the cam itself shows wear marks but I can't feel any with my finger. You think I can get away with just a new cap?

The other picture shows the end cap. I had to tap this bearing off with a punch. It was on there pretty tight. Also, note the burned oil stain on the cap too. It been getting hot. Again the cap looks worn but the cam itself doesn't feel worn, just looks it. Anyone have thoughts here? Do I need a new cam?

The bike has low miles, under 7K.

 

[IAG]

Looks like an oil supply issue- has the cylinder head been removed?

 

[Tree Hugger]

If the bike has only 7000km seems strange that valve clearances are out?

 

[Laverdian]

From the description, it could be that the cam blocks were not properly aligned within the head when last fitting the camshafts. Inspect the block land areas on the head and the underside of the cam block for crush damage. Not uncommon on the 120 engines.

 

[TeddyG]

If you need new cams and have trouble finding them, I've heard that Magacycle in CA does good refurbishing work.

 

[parrishsteve]

I don't think the heads have ever come off. It's definitely an oil supply problem (thanks IAG). As a matter of fact, upon further inspection, I noticed the oil passage hole in that bearing is sealed over from melted aluminum...so its been getting NO oil for a while.

Although that cam block was seated correctly, it was very very loose when I went to remove it, thus having the same effect as a mis-aligned bearing (I remembered this after your comment Laverdian, so thanks!!). I think the root cause is that bearing came loose, and the oil pressure inside that stud cavity where the oil comes out was bleeding off at the base and not getting to the oil passage, thus starving the bearing of oil.

Now, the middle bearings. Any thoughts? The bike sat for a long long long time before I bought it, could that scaring be from trying to start a sitting bike with dry bearings over the years?

 

[RGS1000RGS]

I don't think the heads have ever come off. It's definitely an oil supply problem (thanks IAG). As a matter of fact, upon further inspection, I noticed the oil passage hole in that bearing is sealed over from melted aluminum...so its been getting NO oil for a while.

Although that cam block was seated correctly, it was very very loose when I went to remove it, thus having the same effect as a mis-aligned bearing (I remembered this after your comment Laverdian, so thanks!!). I think the root cause is that bearing came loose, and the oil pressure inside that stud cavity where the oil comes out was bleeding off at the base and not getting to the oil passage, thus starving the bearing of oil.

Now, the middle bearings. Any thoughts? The bike sat for a long long long time before I bought it, could that scaring be from trying to start a sitting bike with dry bearings over the years?

If the bike has sitting for a long time peior to starting, it's good practice to remove the spark plugs, and cam cover and turn the motor over initially by hand to lift the oil and prime the oil system before running. Once you observe oil appearing at the cams, you can then turn over on the starter motor.

 

[andre g]

Again what I told to Kermit, check if the oil pipes and the oil cooler have a free flow and there are no aluminim particles visible, also check the filter element whether there are al particles or silicone or other sealing materials, those can block the oil flow.
How is the oil, any silver particles in the oil?

 

[parrishsteve]

If the bike has sitting for a long time peior to starting, it's good practice to remove the spark plugs, and cam cover and turn the motor over initially by hand to lift the oil and prime the oil system before running. Once you observe oil appearing at the cams, you can then turn over on the starter motor.

If the bike has sitting for a long time peior to starting, it's good practice to remove the spark plugs, and cam cover and turn the motor over initially by hand to lift the oil and prime the oil system before running. Once you observe oil appearing at the cams, you can then turn over on the starter motor.

Well, it's a bit too late for that. I bought it a couple years ago. I've been driving it around for a couple seasons. My thought it that those middle bearings may have been already damaged before I got it, or when I first got it running.

I guess at this point I'm just curious if I can get away with the cams as is and just replacing the cam bearings..??

 

[RGS1000RGS]

Well, it's a bit too late for that. I bought it a couple years ago. I've been driving it around for a couple seasons. My thought it that those middle bearings may have been already damaged before I got it, or when I first got it running.

I guess at this point I'm just curious if I can get away with the cams as is and just replacing the cam bearings..??

The cams should be usable, but the bearing surfaces could be metal plasma sprayed to repair any grooving. The end cap look as though it has a Glacier bearing insert, which could be replaced?

 

[GregT]

I'd linish the bearing surfaces on the cams - it's basically polishing with a fine abrasive cloth.
The end camblocks if excessively worn can be bored and bronze bushed
The center split block can have maybe ,005in taken off the joint faces and then resized.
If any dowel holes are oversized,stepped dowels can be made up if the head isn't coming off.
And of course clean out the oil passages in the blocks.

All fairly easy for a competent machinist.

 

[andre g]

Fotos of the manuals I have. One allows a clearance of .2mm between cam and bearing, the other .15 mm.