yanmar 3ym20 e giri motore

[giosur]

TARATURA CONTAGIRI , MI SCUSO,MA IN ITA NON LA TROVO.
First, obtain access to the front of the engine. Place one piece of white tape on the face of the large pulley mounted on the engine's crankshaft (usually this is the largest pulley in sight). Illuminate the front of the engine with light from the fluorescent lamp. Run the engine at 1,800 rpm, as shown on the tachometer. If the tachometer is accurate, four stationery, or very slowly moving, white marks will appear on the face of the pulley where the tape was placed. If the tachometer is inaccurate, the tape marks may be rotating in either direction. Adjust the throttle until the four tape marks appear to stand still. Note the tachometer reading. If the difference between the reading and 1,800 rpm is at all significant, look for a small adjustment screw on the back or within the body of the tachometer. Turning this screw slightly should make the indicator needle move to exactly 1,800 rpm. If the speed range of the engine permits, increase the engine speed to 3,600 rpm. At this speed, only two tape marks should be visible on the crankshaft pulley. Repeat the check of the tachometer reading and, if necessary, readjust the tach. The basis of this stroboscopic speed calibration is quite simple. At 1,800 rpm, the engine is turning at 30 revolutions per second. The lamp is flashing at 120 flashes per second, or four flashes per engine revolution. Therefore, if the engine is turning at exactly 30 revolutions per second the tape mark will appear four times, with each apparent tape position 1/120 of a second or 1/4 revolution apart. When the engine runs at 3,600 rpm there will be only two light flashes per engine revolution. If the boat is in a country where the standard AC power frequency is 50 Hz, the check speeds would have to be 1,500 and 3,000 rpm since the light would flash 100 times per second.


Don't use the boat's generator to power the lamp when doing this calibration test. If the genset is off frequency, the calibration will also be inaccurate. It is possible, however, to make use of the engine to check the frequency of the genset. After adjusting the engine speed so that the reference mark on the crankshaft pulley is exactly stationary, connect the fluorescent light to the output of the genset. If the frequency of the genset is precisely 60 Hz, the reference mark will still be steady, not rotating. If the reference mark is rotating slowly don't worry, maintaining precisely 60 Hz is not critical for most uses of shipboard AC power."