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Quick question about an old Sun Tachometer

Z

Zwolle

New member
I have a 2000 Johnson 225 HO outboard that, from the looks of the spark plugs, looks like it's idling rich. I was going to buy a new handheld tach so I could adjust the idle mixture, but most reviews said the new tachs are cheap and inaccurate. So I have an old Sun dwell/tachometer laying around. If I connect the hot side of the tach to the primary wire on coil No. 1 and ground the other side, will I get a good reading or will I smoke the old Sun tach?

Much obliged for you time.

Z
 
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You cannot adjust idle mixture with a tach or engine out of the water. has to be in water, in gear with load to adjust.
 
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If you can get engine deep enough to simulate boat floating in water to create needed backpressure, then sure you can do it that way...
 
Meh, It's not deep enough. To the lake I go. All I have is a 130 gal watering trough. It gets the motor pretty far in the water, but about 4 inches shy of the boat floating. Front to back it has plenty of room (there is about 2-1/2 feet of free water behind the lower unit)

Much obliged for the advice.
 
I've been tied up at work. Going to try and get it close in the watering trough tomorrow, and then take it to the lake for a last go round. It has been forever since I had it tuned up. It smokes like a mosquito truck at idle. All my curtain climbers are grown so now I figure I'll get back to the fun stuff. I'll let you know tomorrow.

I also want to test all the warning system for the VRO, etc. due to the age on all the parts. I'd rather limp home to fight another day than have a 420lb paper weight.

I have the original service manual and found where the gray wire comes out of the power pack that goes straight to the tach (and the VRO). I'm going to try and put a tap in that wire to attach the Sun Tach. If I figure I might as well. I'm gonna keep this engine until it dies or I do. :cool:
 
So - long story short a Sun Dwell/Tachometer does not work on a multi-coil 2 stroke motor, sad to say. The gray wire that comes out of the power pack is the pulse wire for the tach in the dash. I did not attempt to hook the Sun up to the primary wire for coil number 1 because I figured even if it did not smoke the box, it would not work. The tach is built to sort the RPMs for all cylinders, not just one. I should know that.

On the bright side I got the plugs changed, SP wires changed, carberators sync'd and adjusted, Max timing adjusted, lower unit lube changed and figured out that my Quick-Start does not work.

I tested the white/black wire which should be open, but found it closed to ground when the engine was below 89 degrees. I have not pulled the temperature switch out to test it in oil for the high temperature circuit... I had no idea that little dual circuit sensor could cost so much.

I'm much obliged for all that helped here.

Tight Lines,
Z
 
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