larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Mar 21, 2021 19:49:22 GMT -5
I have a quick question. I have a Kymco agility 50 with a DC cdi and I want to add a tachometer. Should I connect to the COIL+ or the trigger wire going to the DC CDI? I was thinking the coil is best but, I keep questioning my thoughts. Let me know yours.
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Post by FrankenMech on Mar 21, 2021 22:37:54 GMT -5
Use the connection method specified in the tachometer instructions.
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Mar 22, 2021 9:31:02 GMT -5
I do not have the instructions. I have 3 wires on the tach. ground, Pos, and signal. I hooked up the ground and positive but I wanted opinions on whether to hook to the pick up trigger coil or spark coil.
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Post by FrankenMech on Mar 22, 2021 12:30:46 GMT -5
Find the instructions.
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Post by aeroxbud on Mar 22, 2021 12:56:42 GMT -5
What make is it? Someone might know.
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Post by snaker on Mar 22, 2021 13:10:54 GMT -5
If you have to guess, I would try the coil first, should be less risky to the CDI.
You should be able to tell if the display is in the ballpark.
Keep in mind that the GY6 crankshaft mounted pickups give 2x the needed signals, wasted spark (assuming yours is 4 stroke.
So the tach should be set for that or you will have to half the readings
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Mar 22, 2021 19:38:21 GMT -5
Yes I have a qmb139 4 stroke. DC cdi system and the tachometer is just a cheap Chinese one analog. It has 3 wires 1 pos 1 neg and 1 signal. I do not need instructions for the tachometer. What I am looking for is the best place to get the signal from as it is NOT factory wired for a tach. I have read to use the coil+ and I have also seen to wire it to the pick up coil. I think if I use the pick up I will have too many pulses.
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Post by FrankenMech on Mar 22, 2021 20:06:21 GMT -5
There are different types of 'cheap Chinese one analog' type tachs. If we knew more about yours we might be able to help. Otherwise it sounds like you can experiment with different hookups by yourself. BTW, the pickup coil will give the same number of pulses as the coil.
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Post by GrumpyUnk on Apr 3, 2021 8:58:32 GMT -5
CDI trigger from the flywheel pickup and coil pulse count will(SHOULD) be exactly the same. CDI causes coil pulse. The coil pulse will be a stronger signal, which most coils will need.
You can connect it all, except signal, and then touch the signal wire to the coil and see, or try the trigger signal first(just touch for a second). My bet is the coil wire is what will work. Not all require a strong signal, but most will.
tom
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larryhobman
Scoot Enthusiast
Posts: 117
Location: Delaware beaches
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Post by larryhobman on Apr 3, 2021 11:48:54 GMT -5
Thank you Tom.
That is what I thought, I just wanted see if I was right.
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