After Run Oil: After running, empty the fuel tank and then restart the engine to burn the remaining fuel from the fuel lines and engine. Squirt some oil into the crank-case via the breather
nipple on the crankcase. You should have a few inches of fuel tubing permanently attached to the crankcase breather nipple that is normally open to the atmosphere. It is easy to squirt oil into the
crankcase through this tubing. Use Marvel Mystery Oil (the air tool version is better), or any other brand of air-tool oil such as Snap-On Air Tool Oil. Other popular after-run oils are a 50:50 mixture of
transmission fluid and air-tool oil, just transmission fluid, Mobil-1 synthetic oil, or any light oil such as 5W30. WD-40 is not recommended.
Some people never use after-run oil and claim they never have a problem - take your choice - oil will do no harm so why not use it. Four-stroke engines are susceptible to internal rust on steel parts such
as bearings, and after-run oil is helpful for preventing rust and possible consequent bearing failure.
Adjust Valve Clearances: The valve clearances should be adjusted occasionally (I do it once per year for frequently used engines). Saito provide a small thickness measuring device with each
engine. The Saito thickness guage is 0.10 mm thick and can be used to determine if the valve clearances exceed the maximum recommended value; however I am unable to see how it is to be used to make a
correct setting. It is best to use feeler guages, or thickness gauges, obtainable from an auto parts store to set the clearances in the recommended range. The recommended range is 0.002 to 0.004 inches (or
0.03 to 0.10 mm) and I set the value about 0.002 - 0.003 inches.
To adjust the valves : first remove the valve covers and then rotate the engine shaft until the valves are closed on the compression stroke. When the valves are closed
you will be able to jiggle the tappet rocker arm up-down a little when you grasp it with your fingers. Next loosen the lock nut and turn the adjustment screw to get the
proper gap. The 0.002 inch gauge should easily slide through the gap with no friction whatsoever. Thicker gauges such as 0.005 should not slide though the gap, or
perhaps will go through the gap with some forcing. Tighten the lock nut and re-check the gap. Oil the rocker arm pivot and drip some oil down the push rod tubes, then re-install the valve covers.
Note: Some purists, or mechanical nerds, will tell you that the above method to set the valve clearances using thickness or ‘feeler’ gauges is not the most accurate
method. They argue (correctly) that use of a dial gauge is the better more precise method because after some engine wear the surfaces either side of the gap to be
measured are not precisely flat. Therefore use of ‘feeler’ gauges results in a slightly larger gap than suggested by the thickness of the gauge. While this is strictly correct, I
suggest the minimal difference is not significant, and use of a dial gauge is not something the average flyer is willing to fiddle with.
Repairs and Spare Parts
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