Translations:KAVAN FS400AR - Instruction manual/38/en

A: To check the valve clearances:

1. Remove rocker cover by unscrewing the hex cap screws from the rocker box on the top of the cylinder head. Use the hex key supplied with your FS 400AR to remove the hex cap screws.
2. Turn propeller until compression is first felt. Once you feel compression, turn the propeller an additional 1/4 turn. At this position, both valves should now be closed.
3. With the valves closed, the required valve clearance is between 0.04 mm and 0.10 mm (0.0015 to 0.004 inch) measured between the valve stem and the rocker arm. Use the 0.04 mm and 0.10 mm feeler gauges to check clearances. (See Fig. 29) If tolerances are within range, move to step 4. If tolerances are outside of range, see NOTE and move to step B.
4. It is important to ensure that the valve clearances are consistently within range. It is for this reason that all valve clearance checks are completed. Rotate propeller through compression stroke (approximately 2 rotations) and complete steps 2 & 3 again to ensure that tolerances are within range. Complete step 4 again.

Note: In most cases, the 0.04 mm feeler gauge should pass through the gap, while the 0.10 mm feeler gauge should not. However, if your engine is starting easily, and running satisfactorily, it may not need any adjustment, even if the valve clearance is below 0.04 mm, and up to 0.14 mm (can be tested by having 0.04 mm and 0.10 mm on top of one another).