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Tech Tips Index > Yamaha Grizzly 600/660/700 Sign up or Logon

Grizzly 660 - Valve Adjustment

by dknarnd, 2005-03-23

  • Remove the left front tire. (You can get into the exhaust valves from
  • Not necessary but I also remove the right front tire and work from that side also.
  • Remove the front rack.
  • Remove hood underneath the rack.
  • Remove the gas tank cover.
  • Remove the gas tank.
    - Use a long extension and 10mm socket to reach the front two tank bolts, don’t loose the two spacers.
    - Remove fuel shut off knob.
    - Remove fuel line.
  • Remove white plastic under tank.
  • Remove left side engine cover.
  • Remove pull starter. Be careful with these bolts they will break eaisly, and at assembly I like to use anti-seize on these bolts.
  • Make sure all dirt has been blown or brushed off before removing the spark plug, valve covers and timing cover plug.
  • Remove timing cover plug.
  • Remove spark plug.
  • Remove intake valve cover.
  • Remove exhaust valve covers.
  • 2003 Intake valve clearance 0.004 ~ 0.006 in. (0.10 ~ 0.15mm)
  • 2003 Exhaust valve clearance 0.006 ~ 0.008 in. (0.15 ~ 0.20mm)

    Finding TDC

    Make sure you find the single line ( _ ) to line up on the housing. There is another set of marks connected with a line that looks like an ( I ) ,do not use this.(that is a capital I with the line across top and bottom) To find the correct mark turn the crankshaft counterclockwise very slowly while looking into hole, you may need a flashlight. If you go past the mark at all do not go backwards, continue counterclockwise and start over. I use a long plastic straw placed inside the spark plug hole and watch the stroke sequence, when a valve opens it appears to move downward from above.

    Watch the valves to determine the corresponding stroke.

    1. INTAKE STROKE (000° - 180°) - Intake valves open at TDC then
    as the piston moves down to BDC they close.

    2. COMPRESSION STROKE (180° - 360°) – All valves closed from
    BDC as the piston moves up to the next TDC and this is WHERE
    YOU NEED TO BE to adjust the valves.

    3. POWER STROKE (360° - 540°) – Piston moves down after spark
    ignites fuel and all valves are closed to the next BDC.

    4. EXHAUST STROKE (540° - 720°) – Exhaust valves open and
    close as piston moves up to TDC and this is NOT THE CORRECT

    After finding TDC loosen the locking nuts and make sure the rockers are free enough to allow the feeler gauge to work. Wiggle them with your fingertips before adjusting just to get a feel for the movement of them. Then put a finger under and lift slightly as you slide the feeler gauge under the valve. It has been suggested that you should place a feeler gauge under each valve, but I do not do that. You need to adjust the valve so that you can pull the feeler gauges out with a little drag but you will not be able to push them back in eaisly or at all. Once the valve is adjusted leave the feeler gauge in and tighten the locking nut. Make sure that you torque the locking nuts correctly. (2003 is 10 ft * lb) I do not use a torque wrench just do it by feel. You can practice on other bolts to get a feel for the 10lb neighborhood. Before putting it all back together, valve covers have to be on, start it up and listen to it, a slight ticking sound is normal. There should be enough fuel in the bowl to do this without installing the tank.

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