Valve Adjustment on 2001 DRZ 400
First we'll have a little disclaimer. If you work on your own equipment, you are responsible for it. Don't come whining to me if you break something. If you aren't comfortable with your mechanical skills, then don't practice on your motorcycle... practice on somebody else's. (just kidding)
Checking your valves is pretty easy to do. Most people with enough skill to remove a bolt with the right size wrench can handle it. And no, beer, contrary to popular opinion, does not increase your mechanical abilities. It simply makes working on things fun. I highly recommend you obtain a shop manual for your bike before beginning a job like this. Each model may have some quirk that you find out about in the manual. The manual will also contain the all important torque specs for the fasteners. Torque specs are something that many people over look. When using steel bolts in aluminum pieces, torque is very important. Too loose and the effects are obvious. Too tight, which is the most common problem, and you can disfigure the threads in the aluminum. Sure it may work for a few times, but the more you disfigure the threads the more likely they are to come out all together.
Ok, enough of the disclaimer crap. The DRZ has been known to have an extremely long wearing valve system. Most modern shim under bucket systems have extremely long maintenance intervals. Unlike the 1000 to 3000 mile intervals of the old school rocker arm systems, shim under bucket systems have been known to go for 100,000 miles or more and not need any adjustment. Most DRZ owners have never had to adjust their valves. Many would think that after reading reports such as these that checking the valve clearance would be a waste of time. Don't let your self fall into that thinking. Sure you may be ok skipping a maintenance interval here or there, but the truth is, checking the valves on the DRZ is very easy to do. So why risk it?
To check the valves on the drz, you need to start by removing the radiator shrouds. You can get away with just undoing the bottom shroud bolt if you are in a hurry, but it's easier to get to the fuel tank bolts with the shrouds removed. There are three bolts on each shroud. This is a good chance to clean the crap out of your radiator fins. You may also want to straighten any fins that have gotten smacked around or squashed.
Next you will need to remove the seat. There are two bolts at the rear of the seat. These bolts need to be removed before the seat will come off.
The seat will come off by pulling the rear of it up and then back.
Under the seat, at the rear of the tank, you will find a rubber strap with a metal hook connected to a screw on the tank. You will need to pull the hook off of the screw.
There are two bolts holding the front of the tank to the frame. They are at the front bottom edge of the tank. You will need to remove those bolts.
Next you need to disconnect the fuel line that feeds the carburetor from the tank. Make sure you have the fuel turned off and there are no flames in the garage. Put that big stogie out. Squeeze the clamp and slide it back.
Sometimes the hose will be stuck fast to the spigot. You can use a semi sharp object to work between the rubber and metal of the spigot. In this case I used a dart that had been abused in a prior life. Pull the fuel line off.
Make sure the vent hose on the fuel cap is removed from where ever you have it stuffed and gently lift the tank off the frame.
At this time take a few minutes to clear any debris that has collected between the frame and fuel tank. Also, check the cables, wires and hoses that are routed under the tank. Check and make sure nothing is chaffed and or broken. Make sure to clean any mud dirt and any thing loose that can fall down into the engine.
Trust me, you will only drop something down into an engine once. If you know you've dropped something into the engine, you will have to tear it apart to get it out. If you don't know something has dropped into the engine, then you will find out the hard way. Hey.. is that screw driver bit wedged into those gears? Next there are a few things that need to be removed from the valve cover. Remove the crankcase vent hose.
and remove the oil reservoir tank overflow.
Now it's time to remove the three allen bolts that hold the magnesium valve cover on the engine. Make sure you have a snug fitting allen wrench.
Remove the spark plug wire. Now GENTLY pry the very brittle magnesium valve cover from it's resting place. DO NOT use a metal hammer or mallet to remove it. If it's stuck, then use a rubber mallet. A nice squeaky clean valve cover, in one piece. This is what you should see...
Ok, now that the guts are hanging out, you need to put the machine at top dead center. You need to remove the timing inspection plug. Remove the allen bolt.
The shop manual tells you to remove the magneto plug and use the bolt under the cover to turn the engine, but I've found that putting the bike in 5th gear and using the rear wheel is easier. There are two TDC positions on a 4 stroke. One at the end of the exhaust stroke and one at the beginning of the combustion stroke. You want the one at the beginning of the combustion stroke. It's the TDC where both intake and exhaust valves are closed. This is what the cams look like at TDC.
This is what you should see in the timing inspection port.
Now get a set of the correct sized feeler guages for you valve clearance. Make sure you clean the feeler guages well and make sure you don't have chunks of your lunch stuck to your fingers. There are several methods people use to check the clearance of their valves. I like to start with the larges clearance tolerance and work my way down. If the largest clearance size fits in and slides easy then try the next larger size. If it fits in and slides easily then you are going to have to adjust them. We'll cover that in another installment. If the largest allowed clearance size doesn't fit, then try the next one. And so on.. until you get one the fits between them. If it's within tolerance then you won't have to adjust them.
If everything checks out, then you finished. If they need to be adjusted, you will have to remove the cams, which I won't get into yet.. Hey, my valves didn't need to be adjusted, so I'm not going to tear it apart yet. ;)
Checkin those valves..
While you are in there, you might as well replace your spark plug. Get a new plug, don't bother cleaning up the old plug.
Nasty old spark plug.
Nice new spark plug.
Reinstall everything and carefully torque the bolts on the valve cover. You may want to loctite everything upon reassembly. I've made a habit of doing that and it's nice... I don't have bolts falling out on the trail any more. You may want to start the engine up after reassembly and then change the oil right away. That will help flush out anything that may have fallen into the engine. The oil filter should catch everything, but most oil filters run in bybass mode at higher rpms.