Front Cylinder not firing, then tachometer zero'd out - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 3 (permalink) Old 05-27-2012, 03:45 PM Thread Starter
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Front Cylinder not firing, then tachometer zero'd out

Hey, Guys.

I'm posting a new thread as slimvulcanrider asked.

I'm in the process of resurrecting a 1985 VN700 that sat in my uncle's garage for 10+ year w/o being started. I've fixed (I think...knock on wood) the carb flooding issue I had previously by doing a second cleaning/rebuild on the carbs (thanks for all the help from everyone on here), but after riding my now floodless bike for about 1 hour, I suddenly lost some power. I got back home and realized the front cylinder was not very hot compared to the rear and figured out that my front cylinder is not firing. I double checked by doing the spark test on the frame and have verified that the front only is not sparking. The rear is fine (thus the diminished power I was feeling, I assume). At that time the tachometer was still working fine. I let it sit over night, and took it out the next day for about 15 minutes, when suddenly I watched the tachometer zero out, and it has not functioned since. The back light still works, as does the speedometer.

I fished around the forums for quite awhile and saw some say that it could be the ignition coils($$), a faulty connection($), the ignitor ($$$$) or possibly a short in the tachometer ($$$).

I have fairly limited mechanical/electrical experience, but can usually figure things out. I followed the testing procedures in Clymers for the Pickup Coil testing, which tested in the normal range (488 ohms for the black/yellow & black connectors, 470 ohms for the black/white & black/red connectors on the pickup coil side). The Ignition Coil resistance testing showed that the secondary coil resistance for both front and rear was w/in limits (26K ohms), the rear primary resistance was fine at 2.1 ohms, but the front ignition coil primary resistance was only 0.0-0.2. According to the manual, that means a faulty ignition coil (will cost me about $80 to replace). I couldn't do the I.C. ignitor test w/o the $135 Kawasaki meter they suggest.

I had also tested the tachometer according to Clymers by placing a bare jumper wire b/w the brown connectors from the 6-pin connector in the headlight casing, and touching another bare jumper from the female black connector. It was supposed to make the tachometer jump, but it didn't move, meaning a faulty tachometer according to the manual. But I don't know that I was doing it entirely correctly, and a new tachometer looks to be about $250. I have not started tracing wires, partially b/c I'm not exactly sure about how to do that. All the connections have been cleaned w/ a spray electrical cleaning agent and steel wool where accessible.

So my questions are:
1. Is this just a faulty front ignition coil, since the primary resistance is zero on that front coil? I really hope it is, b/c it would be relatively easy to replace. However, on this site, many have said that these don't typically just go out?

2. Why did my tachometer stop working after the fact, not before or at the same time. Did it stop b/c it stopped getting input from a non-firing front cylinder (I hope), or did something short out in the tachometer afterwards ( I hope not...$$$)

3. Is it just my luck that I finally get the carbs straightened out, run the bike for a bit, and then this issue arise?

Any and all help and suggestions are greatly appreciated in advance. This forum rocks.
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post #2 of 3 (permalink) Old 05-27-2012, 07:03 PM
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2. Why did my tachometer stop working after the fact, not before or at the same time. Did it stop b/c it stopped getting input from a non-firing front cylinder (I hope), or did something short out in the tachometer afterwards ( I hope not...$$$)
The tach sensor does get its signal from the front cylinder ignition coil or spark plug wire, but I do not know exactly where the physical connection is. Also not sure why the tach would continue to function for a time if the coil and cylinder loose power. It just gets curiouser and curiouser.

Gordon

1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
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post #3 of 3 (permalink) Old 05-27-2012, 07:07 PM
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it sounds like you have a bad ignition coil.
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