Checking Valve Clearance on a 2004 KLR-650

Objective

Valve clearance adjustment is required at regular intervals. My manual specifies checking every 10,000 Km. For me, checking and, when necessary, adjusting is the most technically challenging thing I’ve done. For that same reason, it’s the most satisfying, and the most money-saving.

This job takes a long time — allow 4 to 8 hours, with a trip to the shop at the halfway point.

Perhaps that needs clarification. This job took me 4 to 8 hours and, if you have never done this kind of thing before, it will probably take you that long. Maybe a little less, because I was pausing to take pictures. No doubt experienced mechanics can do it in a hour, with one hand, while grooming their dog with the other.

Required

Tools Required

  • Rear stand (recommended)
  • Factory service manual or 3rd-party manual such as the Klymer (there are too many critical specifications to go without, and I can’t promise yours will be the same as mine. Get the manual, and use my description here just to help you understand the steps).
  • Phillips screwdrivers
  • Hex wrenches
  • Metric sockets.
  • Torque wrench
  • Feeler gauges in the appropriate range. As much graduation as you can get in the 0.1mm — 0.3mm range is what you are looking for.
  • Micrometer (not actually required; in theory you can do the calculations with the shim-type code marked on the shim, and the shim substitution table in your service manual. I prefer to measure and do the subtraction myself.)

Supplies Required

  • Replacement shims (but you need to do half the job before you know how many or what sizes)
  • Possibly a valve cover gasket (with care you can reuse the old one but I keep a new one on hand just in case)
  • RTV silicone sealant

Difficulties & Warnings

Some difficulties could be:

  • It takes a long time because of the number of steps and the amount of disassembly required. Also, because you must do a bunch of work before you know the details of a part (replacement shims) you need, it requires a trip to the motorcycle shop mid-job, so you probably are forced to take at least two days to do it. Or, you can buy a complete set of shims — one of each size — in advance (about $75 on eBay) to improve your chances of already having what you need.
  • Also, check if your bike shop keeps shims in stock. If they have to order them for you, your bike will be out of commission while you await the order. Usually they have a complete set in the service department and will, if you ask politely, sell you stock from their service set. Some shops will also take your old shims in trade.
  • Lots of opportunities to drop small parts into dark corners
  • Correct torque of engine bolts is critical
  • Correct re-installation and alignment of cam chain is critical (only done if actual shim adjustment is needed, not for just checking clearances)

Procedure

Unfortunately the time I took these photos the valves were in-spec, so no adjustment was required, so this article only covers checking the clearances, not adjusting them. Next time I will probably have to adjust, will take photos, and will fill out that part of the procedure. Meanwhile, there is a reference below to the adjustment procedure for another bike.

Putting the bike on a rear stand makes this job much easier by levelling the bike and holding it steady.

First you must

  1. Remove the seat
  2. Remove the gas tank

Then:

Since this job involves removing a lot of small parts, I like to have a divided parts box on hand, and place the parts in it, in order, as they come off. The 6 screws involved in removing the seat go in the first compartment, then the 4 for the gas tank go in the second compartment, etc.

This makes it far easier to ensure that all the parts go back where they belong and in the right order.

With the gas tank removed, you can see the top of the engine. The top cover, above the black gasket, has to be removed. It is held in place by 4 bolts that are easy to remove, but the challenge is getting the cover lifted off with the small amount of room that is in there under the bike frame. So we need to spend some time clearing obstacles out of the way.
Here’s the cover from the other side. Again, you can see several other bike parts that will be in the way.
First we’ll remove the cooling fan from the back of the radiator, since its motor housing is in the way.
Remove the electrical connection from the bottom of the radiator.
To free up the wires to the fan itself, bend open two small soft metal clips that hold the wire bundles.
Remove the 3 10mm fan mounting bolts.
Notice that one of the bolts has a ground wire with an eye attached to the bolt. Remember this wire when re-assembling later.
Just hang the fan over the top of the front fairing, out of the way.
The gas tank was sitting on two thick rubber disks, one on each side of the frame. Pull these off and set them aside.
The wires to the spark plug and temperature sensor, visible from the right hand side of the bike, are in the way.
Remove the spark plug wire by pulling the coil upward sharply.
And remove the thin wire leading to the temperature sensor by pulling the connector off the lug.
You do not need to remove the spark plug itself — leave it seated in the engine.
Clean the accumulated debris off the valve cover so it doesn’t fall into the engine when you open it.
Remove the 4 cover mounting bolts and set them aside.
Just above the cover on the right hand side, there is a black plastic connector block of some kind (whose function I do not know) connected to the frame. That’s in the way too, so remove the single mounting bolt and move it aside.
Tug up on the valve cover and it will break free of the gasket seal.
Do this on both sides, so the valve cover is loose.

Now the hard part — getting the cover out of there. You must lift the left side and remove the cover out the left side of the bike. You have to lift it as high as possible before pulling it out, so the cover clears the cam timing chain and wheel on the left side of the engine.

You will be sure it doesn’t fit and you’ll need to struggle with various angles for a while. Pressing the nearby radiator hose out of the way may help.

Suddenly, all the angles line up and it will slip free like it was never a problem.
Locate the rubber gasket — it may be stuck to the cover or to the engine — and carefully remove it.

If it is undamaged, you can carefully clean the old silicon off it and use it again. If it is broken or torn you will have to replace it.

For your first time doing this job, you may prefer the confidence of spending the $10 and putting in a new one. (I keep a new one on hand just in case, but haven’t had to use it.)

Here is the left-side view of the engine with the valve cover removed.
And the right-side view.

Standing on the right side of the bike, look into the engine. You can see 4 pear-shaped cams of highly polished metal. Each one presses down on a shim, and on a valve, or releases it, as the cam shaft rotates. The shims are the dull gray disks the size of a Canadian Loonie immediately under the cams. There is one visible under the bottom left cam in this photo.

The two cams toward the rear of the bike (on the left in this photo) are over the intake valves, while the two toward the front are for the exhaust valves.

You will be measuring the clearance between each cam and the shim underneath it.

The cams need to be in specific rotation positions for this measurement. In this photo they are pointing in various random directions, whereever the last use of the engine happened to leave them. This won’t do. Next we will rotate the engine and the cams to exactly the right position for measurement.

On the left side of the bike, locate the large roundish cover with two slotted plastic plugs in it (circled in green here).
Using a large slotted screwdriver, remove those plastic plugs.

The upper one (circled in red here) reveals a rotating disk with some reference marks, called timing marks, engraved on it.

The lower one (circled in green here) reveals a large hex bolt head that can be used to rotate the engine counterclockwise.

Fit a socket to the rotation bolt and gently rotate the engine counter-clockwise while looking through the inspection window.

Only turn the engine counter-clockwise. If you overshoot a timing mark, go around another time, don’t try to back up.

You will see various engraved marks go by. Stop when a line, and the letter “T”, lying on its side, are centred in the window. Click the photo to the right for a large version to see what this looks like.

The “T” is for “Top Dead Centre” and indicates the piston is at the exact top of the engine. This also means all the valves will be fully open, which is what we want.

Unfortunately, there are two “top dead centre” positions, and some confusion in the documentation I’ve found about which is appropriate. I believe the one in this photo is the one we want. Note that all 4 cams are pointed “out”, away from the centre of the engine.
This is the other setting, with the cam lobes all pointing “in”. This is not the position called for in the manuals — you want the “pointing out” one above. (I suspect that it doesn’t matter, as long as the cams are milled symmetrically, which they should be.
Here are the cams on the exhaust side, toward the front of the bike.
And here are the cams on the intake side, toward the rear of the bike.

Unfortunately, my photo of the actual measurement of clearances was spoiled by carelessness. Next time I do this I’ll fill in this photo. Sorry about that.

But what you do is measure the clearance between each cam and the shim underneath it by sliding various sizes of feeler gauges into the gap, looking for one that fits with some resistance.

Here is a photo of doing this on a different bike (a ZX-6R).

It’s easier on the KLR because there is much more space to work in.

Check all 4 valves (2 intake, 2 exhaust) and write down the clearances, carefully recording which one went with which valve. Here is the table I wrote down doing this check just now.

The manual says that the clearances should be 0.10 to 0.20 mm on the intake side and 0.15 to 0.25 mm on the exhaust side, so the numbers measured here are in spec — no adjustment is required.

Right Left
Intake 0.12 mm 0.11 mm
Exhaust 0.16 mm 0.20 mm
Target Range
Intake 0.10 to 0.20 mm
Exhaust 0.15 to 0.25 mm

If any adjustment was necessary, we would do it here.

Next time I do this service I expect I’ll have to do adjustment, and will document it here. Briefly, the steps are:

  1. For each valve whose clearance is out of spec, calculate the different shim size that would put it in spec. (Calculate how much out of spec the gap is, measure the thickness of the current shim, add or subtract the deviation to calculate what size the shim should be)
    • You can do this by measurement and math. Just measure the thickness of the shim with a micrometer. A thinner shim will make the gap bigger, and a thicker shim will make the gap smaller.
    • Or, your service manual will contain a table in which you can look up the current gap size and the code stamped on the shim, and it will tell you what new shim you need. Personally I find that a very complex way to avoid subtracting two numbers, and I prefer to just measure and subtract.
  2. Buy replacement shims of the needed sizes (or take them out of the set you already have on hand).
  3. Remove the cam shafts, getting access to the shims (also involves removing the cam chain and the cam chain tensioner).
  4. Replace the out-of-spec shims with the new ones.
  5. Replace the cams shafts (also involves re-installing and resetting the cam chain and the cam chain tensioner).

It’s not hard, although it takes a bit of time, and the re-installation and re-synchronization of the cam chain can be a little intimidating until you have done it once.

For now,  here is a link to doing this procedure on a different bike (harder) just to give the general idea.

Having checked, and possibly adjusted, the valve clearances, we now need to reassemble the valve cover.Using a fingernail or a soft tool like a piece of plastic or a popsicle stick, carefully clean off any old silicon sealant that may be stuck to the rim around the engine casing. Also wipe away any oil or grit, leaving a clean flat surface.

Lay the valve cover gasket down and put a thin layer of RTV silicone sealant all around the surface that will face down, with a little more sealant and a little more attention around the two “half moon” shaped bumps on the gasket (circled in green here).

Carefully install the gasket on the engine head, making sure it is perfectly lined up with the edges all around, and pressing gently down so the sealant grabs hold. Make especially sure that the sealant has sealed the half-moons into the half-moon-shaped depressions in the head.

If possible, take a break for a few minutes to give the adhesive time to grab hold.

Reversing the removal process, struggle with the cover until you get it back in under the bike. This time you have the extra challenge of being careful not to dislodge the gasket.
Slowly and gently press the cover down all around, ensuring that the gasket doesn’t slip out of position, and that the ridge on the gasket mates with the groove in the cover.

Now we’ll replace the cover bolts.

You might not have noticed, when you removed them, that they are not all the same. Two are longer.

The shorter two go on the left side, adjacent to the raised part of the cover where the cam chain is.

Put the bolts in place and snug them up, then use a torque wrench to bring them to the specified torque.

My manual calls for 8 Newton-Metres. That’s not very tight — if you’re doing this by hand without a torque wrench (which you should not be) it’s just a bit more than snug with a socket wrench.

You’re Done

That’s it. The rest of the reassembly is just a careful reversal of the disassembly steps: put all the bits back in place around the engine head, then reinstall the gas tank, seat, and fairings.

(While you still have the gas tank off would be a great time to remove and service the spark plug, if that is on your to-do list.)

As soon as possible, test-run the engine and carefully check for oil leaks around the valve cover gasket. The most common problem with this procedure is that if the gasket is not installed flat and clean and well-aligned, oil will leak out around it. It’s not subtle — if you have it wrong you’ll know quickly because the oil will trickle over the hot exhaust header and smoke.

That was a pleasant afternoon, and a saving of a couple of hundred dollars. Thanks for following along with me.


4 Comments

  1. I’m pretty sure you have the cam lobes pointing the wrong way in the picture, they should be pointing out wards.

  2. Well done. My bike has only 3500 miles, but I still intend to check the valves this winter regardless.

Leave a Reply

Your email address will not be published.