Valve Adjustment Procedure - Yamaha MX825V-EFI Service Manual

Model : MX825V-EFI
SERVICE TIP

Valve Adjustment Procedure

1. Place the first cylinder at TDC on the compression stroke (either cylinder, order is not critical).
2. Measure the clearance between the rocker arm and the valve adjustment shim, as
shown in the illustration, using the Go – No Go system.
Intake 0.04～0.08mm (0.0015~0.003 in)
Exhaust 0.08～0.12mm (0.003~0.0045 in)
For example, on the intake valves: a 0.04mm feeler gauge blade should slide in easily,
but a 0.08mm gauge should not – if so, the clearance is within the correct range.
3. Adjustment shims* are only available in 0.05mm increments, and in most cases a shim
one size thicker, or one size thinner will usually bring the clearance within spec.
• If the 0.08mm gauge slides in, try a 0.13mm feeler gauge – if 0.13mm feeler does not
slide in, replace the installed shim with the next thicker shim, and recheck the
clearance (ex., installed 280, replace with a 285)
• If the 0.13mm slides in, it may require a shim 2 or more sizes larger.
4. To remove and install shims, remove the rocker arm shaft retaining bolt (1) and slide the shaft (2)
out of the cylinder head for the valve(s) that need adjustment – NOTE the location and
placement of the two push rods (3).
5. Remove the rocker arm(s) (4) and replace the installed valve adjustment shim with the new size shim.
6. Reassemble the rocker arm and shaft and recheck the valve clearance (you do not need to tighten the retaining bolt until the clearance is
correct.)
7. When the clearance is correct for all valves, install and torque the rocker arm shaft retaining bolt(s) to the proper spec, reassemble the
remainder of the engine, and adjust as needed, following the steps in the appropriate service manual.
* Shims installed as OEM may be in 0.01mm increments, service parts are only available in 0.05mm increments.
(1)
25
(3)
(2)
(3)
(4)