1.  Don't turn the engine to seat the shim if there is not a shim in every bucket. 
1(b).  Especially don't do this with the starter motor.

2.  The bucket and camshaft contain about the same hardness of material.  If you do 1(b) then you're going to damage the cam lobe and the valve bucket and have bits of metal shavings in your engine. 

3.  When taking the camshaft off to take the damaged valve bucket out to remove the metal shavings, be sure to mark the timing chain at TDC before you remove the cam shaft.  Do this even if you don't plan to remove the camshaft from the chain.  This will save you much time when you have to retime the engine because something slipped.

4.  When you're trying to remove the camshaft, be sure to read the instructions.  Taking out the cam chain tensioner is necessary when reinstalling. 

5.  When you forget to do 4, and then don't read how the tensioner works, and it's way too tight when you put it in, if you turn the engine to try and figure out why the cam chain is too tight, be sure to install the cam bearing holder things.  This will keep your camshaft from coming off and damaging the  pins upon which these sit. 

I have not had a good day of wrenching.  I've made more stupid mechanical mistakes in one day than I have in I believe my entire life....

Quote from: Egaeus on March 19, 2006, 09:26:03 PM

2.  The bucket and camshaft contain about the same hardness of material.  If you do 1(b) then you're going to damage the cam lobe and the valve bucket and have bits of metal shavings in your engine. 

Yikes... 

Quote from: Egaeus on March 19, 2006, 09:26:03 PM

5.  When you forget to do 4, and then don't read how the tensioner works, and it's way too tight when you put it in, if you turn the engine to try and figure out why the cam chain is too tight, be sure to install the cam bearing holder things.  This will keep your camshaft from coming off and damaging the  pins upon which these sit. 

and double yikes! 

So I guess you're in the market for a new head?  How bad is the damage to the cam lobe?  There are a couple of used cams on e-bay right now for ~$50 but if you need a whole new head you're up in the $100-$150 range.  Sorry to hear about your troubles, I've got problems too: http://gstwins.com/gsboard/index.php?topic=24883.0

-M

Yeah, I saw that.  That's some crazy valve clearance!  I guess you could always just take the head off and do a valve job....

The cam lobe only has damage to the edges.  The actual face of it isn't damaged and it seems servicable.  The bucket has some gouges in the edges, but it also works.  I can still put a shim in it.  The metal shavings were isolated to the area around the valve bucket, so I think I got them all out between the magnet and paper towels.  Thank goodness they are tilted the way they are.  The pin is a $0.98 part, and I was able to get it to work for now.  Strangely enough, I don't think any fatal damage was done to anything. 

You need to remove the galled area on the lobes before you put everything back together.  Failure to do so will cause the valve shims to spall in short order as the contact patch of the cam lobe will be very small.

Get a small needle file and some sandpaper.  Very gently blend the galled area on the edge of the cam lobe, then finish with 800 followed by 1000 followed by 1500 sandpaper.  Do not remove any more material than necessary, and avoid surfacing the face of the lobe.

Quote from: GeeP on March 20, 2006, 09:51:50 AM
You need to remove the galled area on the lobes before you put everything back together.  Failure to do so will cause the valve shims to spall in short order as the contact patch of the cam lobe will be very small.

Get a small needle file and some sandpaper.  Very gently blend the galled area on the edge of the cam lobe, then finish with 800 followed by 1000 followed by 1500 sandpaper.  Do not remove any more material than necessary, and avoid surfacing the face of the lobe.

Before I take it apart, are you sure you understood the location of the damage?  The damaged area is on either side of the camshaft lobe.  The contact area is the same except for about 1/16 of an inch on the outsides of the lobe.  The rest is nice and smooth. 

I'm not trying to question your knowledge, just making sure before butterfingers tears into the engine again. 

That's correct.  The reason why I know is because I did nearly that myself.  I had a sticky clutch, and moved the bike in gear with the shims out.  Got about 6" when I realized what I had done.   

That little area will be upset, causing the shim to ride there instead of the whole lobe.  You will be able to feel it with your fingernail.  Don't worry about the sides of the lobe, just where it will contact the shim. 

Gently touch them up with a needle file.  Use oil-soaked paper towels around the area to collect the filings.  (The oil will help hold the filings on the towel when you remove it.)  Keep a magnet handy just in case.

34

The cam bears on *most* of the surface of the shim.  The lobe axis of revolution is slightly off-axis with the projected axis of revolution of the valve.  The result is that the shim and bucket will slowly spin on top of the valve tip.  This slow rotation exposes more of the shim to wear, and will be seen on the shim as a concentric wear pattern.

You are correct that the very center of the shim will have the most wear.  In fact, the shim will wear in a dish-shape.  That's because the center of the shim is subjected to a higher cyclic loading that the circumference of the shim.

You are also correct that the shim should be measured with a micrometer.  For all practical purposes, a dial caliper is rarely repeatable to closer than .001".  A good micrometer in a trained hand will repeat to .00005" very easily.

Keep in mind that temperature plays a big role in precision measuring.  As an object warms up it gets bigger.  As a measuring instrument like a micrometer warms up, the value of it's measurement gets smaller.  Therefore, it is good practice to insulate your workpiece and measuring instrument from the heat of your hands, and to keep the measuring instrument and object to measure at the same relative temperature.  This is why micrometers have plastic pads.  It's also why you never take a micrometer from a hot room into the garage to take a measurement, and why you never take a cold shim from the garage into the house to measure.

To put this into perspective, the ubiquitous "human hair" is roughly .004" to .007" in diameter.  That's the width of an ocean to a toolmaker, and roughly twice the cold valve clearance of the GS.

Edit:  I keep hitting the "Quote" button instead of the "Modify" button.