Original forum post can be found here:
This is NOT my mod. I am posting this for research purposes only. If this procedure is not preformed properly, SERIOUS DAMAGE TO YOUR ENGINE MAY RESULT!! I assume no liability for any damage or harm to your bike or yourself as a result of this modification. Refer to the factory service manual for all torque specifications!!
Ok, so a quick run down of the modification: Eagle Mike and Mike Coe discovered on a 2009 model that if the exhaust cam is advanced one tooth (7.X degrees) that a significant amount of horsepower and torque are achieved throughout the power band (upwards of 7 to 10 percent in some parts of the power band). I have personally found that this mod cut out a very considerable amount of "back popping" on deceleration, and made for a more responsive and smooth running engine with this modification alone.
These pictures are from a 1995 KLR650. There are some differences that I will try to point out along the way. I only have experiences with the first gen, but this procedure should work for most models!
Once again, this is only how I personally have performed this procedure. There are other ways to go about this, but I believe this to be the easiest!
First of all, you will want to follow the guide of your choice for removing the rear fairings, seat, radiator shrouds, and gas tank. Follow your guide of choice for removing the valve cover. If you have not checked your valves in a while, now is the time to do so. There are plenty of valve adjustment guides out there, so use their procedures to get the valves exposed.
Once your valve cover is off, it should look something like this
On these older models, the cam chain guide is on the valve cover itself. On newer models, there is a separate piece that will sit between the cam sprockets. You can see the difference in this picture (not my picture)
I'll get to this in a second.
Now that your valve cover is off, roll the engine over so that the T mark indicating top dead center is lined up with the mark on the stator cover.
Insure that you are on the COMPRESSION stroke by confirming that the cam lobes are facing away from the cylinder.
If they are facing in towards the cylinder, you will need to rotate the crank another 360 degrees and line the T mark up again. Ensure that the T is centered on the mark and that you are at TDC Compression stroke before you go further.
With the engine at TDC, the cam sprockets look like this. Remember if you have the later style chain guide, it will cover up part of the cam sprocket, but you'll still be able to verify this.
On this engine, the line marks in the cam sprockets lined up perfectly with the surface of the head. On my own personal bike, they were a little angled. Just remember that your bike may not be PERFECTLY straight. It's ok, but you'll want to take note of it.
It's time to remove the cam chain tensioner. With the tensioner still installed on the bike, loosen up the 12mm bolt in the middle of it. This will make things easier when it is time to reinstall the tensioner! Once your 12mm bolt is loose, loosen the two 10mm bolts that hold the tensioner assembly in place. You'll want to loosen them evenly so as not to cause damage to the tensioner. At this point it still has tension, so damage could occur if you don't evenly back the bolts out!
You may need to use a small punch and apply some pressure by hand to the tab that sticks out past the cylinder. Use hand force only. Do not beat it with a hammer or you risk breaking the tab!! Once removed, it should look like this:
At this point, since you already have loosened the 12mm bolt holding the spring in, simply unthread it by hand (making sure not to let it go flying when it is unthreaded), and you should be left with something like this:
With your finger, press in on this tab, and the tensioner arm should collapse into the body.
Once it's cleaned up and compressed, it should look like this:
Now that there is no chain tension on the bike DO NOT move the crank again!! You could cause some problems. There should be plenty of free play at this point since there is minimal chain tension.
And you can see that you can pull up on the chain.
Now you will have to loosen up the exhaust cam cap bolts , and remove both exhaust cam caps. Be extremely careful not to drop anything down into the abyss. For models with the large style chain guide, there are three 8mm bolts that hold the chain guide into place. The one that sits under the oil line running from intake cap to exhaust cap will be EXTREMELY easy to drop if you're not careful. If you drop it you will have to take off the stator cover and fish it out with a magnet. BE CAREFUL! The other two bolts that sit towards the outside of the engine are quite long and should be much easier to remove. You can see the two longer bolts in this picture, as well as the threads where the shorter 8mm bolt sits.
Now the exhaust cam can be lifted by hand and moved.
You will want to move the exhaust cam ONE TOOTH counter clockwise. You will probably have to lift the cam up so that the chain doesn't try to bind up while you're moving it.
At this point, your intake cam should be in the exact same place it started at.
And your exhaust cam should be advanced one tooth (or moved one tooth counter clockwise.)
You can see that instead of pointing straight even with the head, it is now slightly lower.
Here is what it looks like with the tensioner out.
Reinstall the cam caps and the cam chain guide at this point.
Now it's time to re-install the tensioner assembly. With the spring, washer, and 12mm bolt removed, make sure that the arrow is pointing down and the removal tab is facing the outside of the bike. This only goes in one way, so if you try to force it in incorreclty, damage could result. This is the orientation for installation:
Installed on the bike:
Now install the spring, washer, and 12mm nut. You should hear the tensioner extend when you put tension on the spring.
On my 2006, I had to move the cam chain a little on the intake side before it took up the slack.
Ensure that you are still at TDC
One final inspection to ensure that the timing is correct after the tensioner goes on.
Now, roll the engine through by hand for a few revolutions. This will be much easier if you pull the spark plug out. With the plug in, you will feel some resistance as the engine goes through the compression stroke, but if you hear anything make contact or if it's REALLY hard to turn the engine over, move the engine back to TDC and reinspect to make sure everything is installed properly.
If the bike turns over easily by hand and the valves are not contacting the pistons (there is no chance of valve to piston contact if this is done correctly) then it is time to reassemble!
Have fun and enjoy the extra power!