johnson tach

[bansheetaz]

73 johnson 115. on the back of the tach there is a dial that you can adjust for 2 4 or 6 pulses per revolution. which setting do i use with this engine. <br /><br /> also how do i idle the engine down. it idles about 2500rpm with the muffs on. i havnt run it in water yet. my manual hasnt arrived yet.<br /><br />thanx for the help<br />troy

 

[Joe Reeves]

Re: johnson tach

Troy.... Set that tachometer dial to number six (6).<br /><br />Now, before you start adjusting the throttle, perhaps the idle is okay but the tach is either set wrong or it may be faulty? An enging actually running at 2500 rpm on a flushette would be pretty scary!<br /><br />High idle..... Rack off the idle set screw that you'll find about halfway up the vertical throttle arm on the port side of the engine (left side as you're standing in back of the engine), then adjust the threaded trunion to reduce the throttle that is on the throttle cable where the cable is clamped in.<br /><br />The throttle adjustment above assumes that everything else is as it should be.... compression, spark, connecting carburetor linkages, etc etc.<br /><br />On a flushette, the idle should be for a 20" shaft engine 1000 rpm, for a 25" shaft 1200 rpm.

 

[bansheetaz]

Re: johnson tach

yea its on 6 right now. the tach isnt working at all right now. i was measuring rpm with a voltmeter using the tach feature. is there any way to test a tach or the wires hooked to it? the engine sounded pretty fast also. the throttle plates look like they are pretty well closed already. maybe i gotta vacuum leak. ill keep looking. <br />thanks for the help<br />troy

 

[Joe Reeves]

Re: johnson tach

Possibly the tach is okay but the rectifier is faulty. The tach (gray wire) operates off of the charging system rectifier (yellow/gray wire). You can check the rectifier as follows.<br /><br />(Small Rectifier Test)<br />(J. Reeves)<br /><br />Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction. <br /><br />Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other. <br /><br />Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires. <br /><br />Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.

 

[bansheetaz]

Re: johnson tach

thanks for the info . i will check all that. <br /><br />the rectifier is brand spankin new and when i had the engine running , the battery voltage was over 13 volts so i figure it was charging. i will double check the rectifier though. <br /><br />thanks again<br />troy