How To: Valve Clearance and Adjustment

Routine maintenance for your XJ600's engine.
Post Reply
User avatar
ammvio54
One of the Regulars
One of the Regulars
Posts: 136
Joined: Fri Apr 24, 2015 1:50 pm

Image

This How-to describes the process of checking and adjusting the valve clearance.

Correct valve clearances that are within specification, are needed for a properly running engine. It's necessary to perform this procedure before synchronizing the carburetors or your efforts will be futile. It's recommended that this procedure is performed every 2 or 3 riding seasons, and more often if you ride during the winter. It's also a good rule of thumb that if you don't remember the last time the procedure was performed, to perform it.

One important aspect is that this procedure needs to be performed when the engine is cold, so keep that in mind the next time you want to do this procedure. It usually takes me about an hour, from start to finish.

The required tools for the procedure:
  • 14mm wrench or socket
    8 mm socket
    5mm hex (allen) wrench
    Small flathead screwdriver
    Tweezers
    Zip-Tie or wire (I recommend a thicker, mid-range to lower gauge)
    Metric Feeler Gauge
Optional tools: 1. Remove the gas tank, airbox, and carburetors.


2. Remove the timing plate cover (4, 8mm bolts) & the valve cover (8, 5mm allen wrench). If the valve cover doesn't want to come off, do not pry at it with something metal, use something that will not ruin the gasket.
Image


3. Remove all four spark plugs (it isn't absolutely necessary at this point but will make turning the motor easier and you will need them removed later anyways).


4. Turn the crankshaft counter-clockwise (using the 14mm wrench or socket) and use the Top Dead Center (TDC) mark is aligned with pick-up coil. There are two of these TDC marks, on opposite sides of each other.


4a. For #1 and #4 cylinder use this TDC:
Image


4b. For #2 and #3 cylinder use this TDC:
Image


5. When looking at the cylinder you are about to perform the adjustment on, the cam lobes should be opposite of each other.
Image


6. When you get the cam lobes opposite of each other, grab the feeler gauge. You want to start with the smallest size on the gauge and put it between the lobe and the shim.
Image


6a.If the smallest one fits (it should) go to the next size up, and so on and so forth until you get to one that doesn't fit between the lobe and shim anymore. You can use two of the sizes on the feeler gauge to make a size in between 2 of the regular sizes on the gauge (i.e. using the .051mm and .203mm to make a .254 that is between the .203 and .279). You want to make these measurements as specific as possible so you can put the correct shim in the bike.
Image


7. Once you have the measurement, record it for later reference. Do this for all 8 shims. The order of measurements is cylinder #1, #2, #4, #3.


7a. Make sure the lobes are opposite of each other when taking the measurement, rotating the crankshaft counter-clockwise (as mentioned in step #4).
Image


8. Once you have all of the measurements recorded for all 8 shims, you need to compare them to the shims already installed in the engine.
Image


8a. If you don't know the size of shims in the engine you will need to remove all of them to compare them with your measurements. We'll get to removal of the shims now.


9. If you haven't already done it, remove the spark plugs. Get your tweezers and small flathead screwdriver ready. Take your wire and bend it into the shape of a number 2; something like in this picture:
Image


10. Take the wire and gently insert the shorter end of the wire into the spark plug hole corresponding to the cylinder and shim you need to remove. Move the wire around in the cylinder and face the short end of the wire toward the shim the needs to be removed.
Image


11. Once you get it in position, turn the crankshaft until the lobes are opposite the shim. This should create a gap between the lobe and shim. If you don't get the wire in the correct position the shim will move up with the lobe and there will not be a gap between the two. IMPORTANT: IF THE CRANKSHAFT DOESN'T WANT TO ROTATE ANYMORE, DO NOT PUSH IT, BACK IT OFF A LITTLE AND RE-POSITION THE WIRE. Once you get the hang of positioning the wire you can usually position it in the correct place the first time.
Image


12. Once you have created the gap between the lobe and shim, rotate the bucket (what the shim sits in) until you can see it the small slot in it. Place the small flathead screwdriver in this slot and pop the shim up, out of the bucket.
Image


13. Next, take the tweezers and pull the shim out of the engine.
Image


14. Inspect the shim, make sure there are no dings on it. If you don't know the size of the shim, flip it over and the size is printed on the one side.


15. Now we're going to compare the measurements we took with the feeler gauges with the specifications to see if the measurements are within the correct range. If the measurements are within the specifications, no action is needed!


15a. If the measurements don't fall into these ranges of specifications you will need to consult a table to see what size shim you need to replace the old shim with. You need to know the size of shim within the engine for this step. This is why knowing what shims are in your engine can lessen the amount of work needed to be done. I generally make note of what shims are in my engine and put the paper with my shim box.
Image


MEASUREMENT VALVE SPECIFICATIONS FOR COLD ENGINE:

INTAKE:
.11MM - .15MM (.004INCH - .006INCH)

EXHAUST:
.21MM - .25MM (.008INCH - .010INCH)


15b. If the measurement doesn't fall within the specifications for the INTAKE, consult this chart.
Image


15c. If the measurement doesn't fall with the specifications for the EXHAUST, consult this chart.
Image


15d. If the shim needs replaced, follow these instructions to understand the chart and which size shim needs to be put in the engine. You need find the installed shim number on the chart (x-axis) and the measurement found (y-axis). Follow the x-axis down and the y-axis across until the two lines meet; the box you land on is the shim size that needs to be installed in the bike. If these instructions were unclear, an example is shown on both charts shown above.


16. Perform this for all of the measurement clearances that did not fit the specifications listed above. If you do not own all sizes shims needed, there is a shim pool on the forum:
http://xjrider.com/viewtopic.php?f=57&t ... =shim+pool


17. Once all correct shim sizes have been discovered, put the shims back in the engine, with the number on the shim facing down (into the engine). Make note of what shim sizes are in which cylinder for future reference!!! Rotate the crankshaft until the lobe compresses the shim back down and then remove the wire from the spark plug hole.


18. Place the spark plugs back in the engine, put the valve cover back on tighten the bolts and tighten them all evenly. Put the timing plate back on, as well as the infills or side fairings, carbs, airbox, and gas tank.


19. After adjusting the valve clearances, you should synchronize the carburetors since the amount of air going into the engine has changed.


20. Have drink of your favorite beverage (I recommend chocolate milk) and have a nice snack. You're all done!! :clap:


Some important information: Do not rotate the engine if there is no shim in a bucket! Be careful not to drop anything down into the engine!


If you have more questions I have included pictures of this procedure from the service manual. They are all in correct order:

Image

Image

Image

Image

Image

This topic has 5 replies

You must be a registered member and logged in to view the replies in this topic.


Register Login
 
Post Reply