XR600R Valve Adjustment by Craig Cullen

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4Strokes
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XR600R Valve Adjustment by Craig Cullen

Post by 4Strokes » Sat May 14, 2016 6:48 pm

  1. Ensure the motor is cold.
     
  2. Remove the fuel tank, fuel line, seat and side covers.
     
  3. Remove the four large valve inspection bolts with a socket the same size as the rear axle nut.
     
  4. Remove the spark plug, place a screwdriver through the hole and rest it on the top of the piston.
     
  5. Remove the timing inspection bolt on the LHS engine case.
     
  6. You want to adjust the valve clearance on the compression stroke, that is when the intake valve has opened and air has been sucked in, then the piston rises up compressing the air. Rotate the motor with the kick starter so that the exhaust valve has just open, and then shut and the intake valve is just about to open. You will feel with the screw driver that the piston is at TDC and the 'T' mark will show through the LHS inspection hole. This is not the correct TDC. Rotate the motor a little further and you will notice the intake valve open up. Keep rotating slowly and you will feel the piston rise again to another TDC. This is the correct TDC to adjust the valve clearance from. If you look through the LHS inspection hole now, you should see the letter 'T', but it might not be perfectly lined up the groove in the case cause the kick-starter spring won't let it sit perfectly. I used a length of string to hold the kick-starter at the perfect angle to line up the two marks. There should be play in all the valve arms at this point. There are several marks, so be sure you have the 'T' mark. The key things to remember are the T mark must be lined up, and there should be some play in all 4 of the rocker arms.
     
  7. With your feeler gauge, (intake is 0.10mm and exhaust is 0.12mm or 0.003" and 0.004"), use a smaller feeler gauge just to see how the clearances are at the moment on the intake valve. If you can't get it in between the bottom of the adjusting screw and the sub rocker arm, the clearances are to tight and need adjusting. If the smaller feeler gauge fits in and is quite loose, try the 0.10mm. If you can get it in without struggling and there is just a light grab on the finger it is perfect so don't adjust it. If it to tight or loose, adjust it. Check the exhaust clearance using the relevant gauge fingers.
     
    Update 5/6/08: Changed valve clearance specifications from 0.010mm to 0.10mm, 0.012mm to 0.12mm, and 0.005mm to 0.05mm, as indicated by David Closs and IVG.
     
  8. Using a 12mm ring spanner, loosen the locking nut. Using a flat head screwdriver, screw the adjustment screw out just enough for you to slide in the correct gauge finger. Screw the adjustment screw back in so it is just applying a small amount of pressure to the gauge finger. You should be able to still slide the gauge finger around, but it should feel like it is grabbing a little. Screw the locking nut down to secure the adjustment screw. When the locking nut is tightened, it appears to raise the adjustment screw slightly and reduce the amount of grabbing on the gauge finger, so experiment and get it all tight but with the slight grab.
     
  9. Continue this for the remaining three valve clearances.
     
  10. Adjust the decompression system if required so it is not affecting the rocker arm action and only touches the rocker arm when you pull the decompression lever. The decompression system cable mount on the cylinder head may cop a few hits and could be bent, so check this, as it will affect the way the decompression system works. Then recheck the clearances for peace of mind.
     
  11. Replace the four large valve inspection bolts and the timing inspection bolt on the LHS.
     
  12. Replace the tank, fuel line, side covers and the seat.
     
  13. Fire her up.
Credits: XR600R Valve Adjustment article written and submitted by Craig Cullen. Edited and published by 4Strokes.com.

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