DRZ Valve Clearance Check and Adjustment plus Cam timing


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  • E.Marquez

Posted August 10, 2009 - 02:26 PM

#1

This preventative Maintenance "fix" is applicable and recommended for all year and model year DRZ 2000 -present

NOTE: This How To white paper is just a guide; it does not replace a service manual, general mechanical knowledge, specific motorcycle repair experience and good old common sense. With the proper tools, some general experience and this guide most users will be able to successfully check valve clearances and if required replace shims to adjust the valves to service specifications. As always if after reading though this guide, you do not feel capable of performing this maintenance task, STOP, ask questions on the forum, take pictures of your point of confusion and get your answers before you start.



TOOLS:
Basic hand tools, all metric

3/8 Drive socket set, 10mm to 17mm
Allen key set 5mm to 15mm
Wrench set 10mm to 17mm
Feeler gauge set that covers up to .30mm

 

TOOLS SUGGESTED:
Magnet on a stick
Digital camera
Pen and paper

You will be taking pictures, writing notes, removing the seat, tank, the timing sight plug on the left cover, the crank access plug on that same cover. Spark plug and valve cover. If adjustments are needed, removing the cam chain tensioner (CCT) and cam caps. Measuring the clearance between the bucket and cam, reading a very faint number printed on the valve shim, or better yet measuring it with a micrometer. This list is not all inclusive, as stated its basic. So if what is shown above is beyond what your comfortable doing, STOP find a Knowledgeable friend to help or take it to a shop.

As you will be opening your motor up, the first step is to thoroughly clean the bike; both the valve cover and left side cover will be open, and accessible to dirt and other debris. Clean, degrease, and start with a clean work environment.

Motor should be cool to the touch prior to starting the valve check.

After bike is clean and dry, remove the seat, tank and set aside.

Remove the spark plug boot, and blow out the spark plug well with compressed air. I like to squirt a shot of brake clean in there, and hit it again with the air till dry. I do this from both directions, the drain hole in the side of the head, and down the spark plug well. No Air compressor? Brake clean is a good second bet.. just not as good as high pressure air.  

Take out the crank access plug. CAUTION: This plug is often over tightened by a previous person, making it difficult to remove. See footnotes at the end of this article for removal of a stuck and damaged access cover plug.

  • Remove the timing window plug on the top of the left cover.
  • Remove the spark plug.
  • Remove valve cover.

Congratulations, you have finished preparing your DRZ to check the valves.

Setting Timing and Checking the valves

Set the motor to Top Dead Center (TDC) on the compression stroke. The timing index mark on the flywheel will be in the center of the sight window (Note your looking to align the index line NOT the T next to it center of the sight window)

TDC_mark.jpg

Looking at the cams from the side the lobes should be pointed at 10 and 2 O’clock
If not and the index line is in the center of the window, you're not on the compression stroke. Try again; turn the motor in the normal forward direction, until the index line is centered.
Cam sprockets.jpg
The cam sprockets will look like this if you’re using OEM cams.
The #3 and #2 should be straight up. The other index lines even with the top flat surface of the head.

So the motor is at TDC now, it’s cool to the touch and it’s time to check the valve clearances.

Take a quick look at the timing mark, and make sure the crank has not rotated and the index line is still in the center of the sight window (this is a repetitive step, but key to getting good readings off valves)

The OEM service limits for clearance is:
Intake 0.10mm ~ 0.20mm
Exhaust 0.20 ~ 0.30mm

So starting with any valve and bucket, pick the feeler gauge blade of the minimum service limit and see if it fits cleanly, without force between the shim bucket and the cam face.

valve check drz.jpg

Starting with an intake valve try a 0.10mm blade, if it does not fit in, your clearances are too tight. Go to the next size down blade in your feeler gauge set until you find one that fits, and write down the size. If the 0.10 blade fits, go up one size at a time until you get to a blade that does not fit. Write down the last blade size that fits.
Do so for the remaining three valves. Bottom line, your job here is to find the blade that fits the valve clearance gap, it should be a slight drag as you pull it though..

If your clearances are too small (below service limit) you will need a smaller (thinner) shim. Swapping to a thinner shim under the bucket will move the bucket farther away from the cam and increase your clearance.
If the clearance was too large (above the service limit) you will need a larger shim (thicker shim) In order to move the valve bucket closer to the cam face.

If your clearances are within the service limit. You’re done, put everything back together and go ride.

Remember as the valve face wears, they recede into the head and the valve clearances get smaller (less) So if you are measuring a clearance close to the minimum service limit,, consider adjusting them now.

Once the hard coating on the valve face starts to wear, the valve clearances will close up in just a few hours. You can adjust them again to service limits, but they will rapidly continue to wear. It’s time for a valve job.

Removing the Cams and Adjusting Valve Clearances

In order to remove the cams to gain access to the valve bucket and below it the shim, you will need to make sure the cams are at TDC (or close) then remove the cam chain tensioner (CCT).

Next break loose each of the cam cap bolts in a criss cross pattern, taking note of the position of each one. You will find two different lengths, two long, 6 short. If you mix up the position later upon install and put a short one in a long hole you will pull out (strip) the threads when you try and tighten it down.

cam cap fastener position.jpg

Once all eight cam cap fasteners are out, remove chain from the sprocket as you remove the cam. Set the cams aside in a protected location, clean and dust free as you can. To keep the chain from falling down, use a long spring, piece of wire or zip tie to hold it up. If it falls free, no worry.. Just retrieve it with a hook before you turn the crank. It cannot fall so far down you cannot retrieve it; nor can it fall off the lower sprocket.

The valve bucket is now accessible, remove it with a magnet, or I sometimes use an old valve lapping tool (suction cup). CAUTION: the small shim (9.48mm dia) may stick to the underside of the bucket, it may come part way out of the valve top, or it could stay in place.. Be careful it does not come off with the bucket and then drop free to be lost in the motor. Retrieving a shim from the motor is possible, but time consuming, and often requires further disassembly and or removal of the motor from the frame. Many hours may be lost doing this..So spending a few extra minutes to stuff clean lint free rags in the open parts of the head is well worth it till you understand what is happening.

What shim do I need to fix my clearances?

Now that you know what the clearance is for each valve, you have the shims out and know what size each is, and you know the service limits it's time to do some math and figure out what shim you need to install.

The OEM service limits for clearance are:
Intake 0.10mm ~ 0.20mm
Exhaust 0.20 ~ 0.30mm
Shims come in two types, The OEM has half sizes or increments of 0.02mm, and the aftermarket ones come in .05mm increments only. You can use either to correctly adjust the clearances. Speaking of shim sizes, the diameter of a DRZ valve shim is 9.48mm.. and then the shim thickness is noted on the shim itself.. Typically they start at about 2.00mm and go up to 4.50mm or so. Normal shims used in a DRZ are in the 2.00mm to 3.50mm. Less than 2.00 or so will often be so thin that the shim would be below the surface of the valve spring top… causing the bucket to push down on the top and not the shim. This will damage the bucket, and often cause the valve locks to come loose.
So for the sake of explaining what shims you need, lest try some math. Assume you want the clearance to be in the middle of the spec. and you’re using an aftermarket shim from Hotcams
Intake valve, measured clearance of 0 .05mm
Valve shim is a 2.50mm
Service limit is 0.10mm to 0.20mm (you decide you want it in the middle of the spec at 0.15mm)
So you need increase the clearance .10mm
That means you need a 0.10mm THINNER shim.
If you install a 2.40mm shim you will end up with a clearance of 0.15mm. Your desired endstate.
One more:
Exhaust valve, measured clearance of .25mm
Valve shim is a 2.85mm
Service limit is 0.20mm to 0.30mm (you decide you want it in the far end of the spec at 0.30mm)
So you need increase the clearance 0.05mm
That means you need a 0.05mm THINNER shim.
If you install a 2.80mm shim you will end up with a clearance of 0.30mm. Your desired endstate.

Timing the cams

Timing the OEM cams.. Not as hard as you think,,,,so just stop thinking... :busted:

This is a very easy thing to do, and often misunderstood or over complicated.

From the start, cams on the table, the only think you have to get right is the crank at TDC.. Line up the timing mark.. There is no "stroke" to move it to, as that is related to the cam position and they are on your work bench.

So set the timing mark center of the window.
Pull up on the cam chain, Install the intake cam with the sprocket timing marks close to the correct position lobes at 10 0’clock.
Install the exhaust cam, timing marks in the general position and lobes pointing at 2 O'clock.
Stick your finger in the hole where the CCT goes, and push against the timing chain guide to take up chain slack.. Check the flywheel timing mark and look at the cam timing marks..
Make note of which cam needs to roll forward or backward to get the timing correct. One at a time, remove the cam, lift the chain of the sprocket and rotate the cam, sit it back in the head and do the other.
Check flywheel timing mark again, push against the chain guide, check the cam timing marks. Adjust again if needed. If not, install the cam caps.. Remember those two longer fasteners…. Get them in the correct holes.
As you most likely do not have an expensive 1/4” drive torque wrench, of known accuracy do yourself a favor, and just snug up the socket head cap screw with an Allen key.
Reinstall the CCT (if using a ACCT, reset it first)
THE NEXT STEP IS VITAL …..
Cams in, caps tight, CCT installed.. Rotate the motor one full cycle, till it is back on compression stroke, flywheel timing mark centered in the window. CHECK the cam timing marks… check the flywheel timing mark, check the cam timing mark. Over kill?? Yes, destroying your motor because you skipped 30 seconds of checking a few timing marks several times.. Priceless.

 

Verify your valve clearances

If you measured carefully before, your notes were correct and math right.. The clearances are dead on where you wanted them. But a few minutes to check is important.

 

You can do this before putting the cam chain tensioner back buy just sticking your finger in the head hole and pressing in on the guide while you rotate the motor over one full rev. This helps squeeze out any excess oil between the shim and cam/bucket.. as well as ensure the shim is fully seated..

 

Follow the procedure found above in Setting Timing and Checking the valves. If valves are in spec, you're done here. 

At this point you're done.. reinstall the CCT, double check your timing.
Reinstall everything you took off, and go ride.


Edited by E.Marquez, August 04, 2014 - 10:28 AM.






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