Engine Stumbles, Tach Spikes - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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Where does this wire go?
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post #1 of 16 (permalink) Old 05-28-2014, 01:04 PM Thread Starter
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Engine Stumbles, Tach Spikes

So, I'm cruising at 60MPH on a cool spring evening in Colorado (Denver altitude, not in the mountains) on my 1990 stock 750 (with about 23,000mi.), and the engine starts to momentarily and intermittently cut out in a manner very similar to the POOGS problem. However, the engine did not die, and out of the corner of my eye I notice that the tach was momentarily spiking UP in RPMs as the engine seemed to hesitate (as much as 1000-1500 on the dial). The problem has persisted now into a second day, and it seems to happen at all speeds and in all gears. I cannot determine yet if it happens with the bike just at idle.

A forum search led to one thread (#19054) which suggested a faulty/loose battery ground connection. I immediately checked that, but it does not "seem" to be the issue. The very last thing I did as far as work on the bike was to synchronize the carbs, but I cannot imagine this would be the cause of the problem.

I realize the tach is electrically (not mechanically) driven so I am posting this in the Electrical Section, but since I am at best just an amateur mechanic, I seems it could be any number of things. Does anyone have other suggestions for a strategy to find out what the likely source problem is?

Thanks for any help you can offer.
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post #2 of 16 (permalink) Old 05-28-2014, 01:07 PM
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I still think it's a ground. Every time mine did that, it was one of the ground wires. (and it did it 3-4 times after I first got it.. had to keep tracking down the various ground cables, and using some loctite.)

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
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Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
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Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

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Last edited by thtanner; 05-28-2014 at 01:12 PM.
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post #3 of 16 (permalink) Old 05-28-2014, 01:47 PM
..have a vulcan good day!
 
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Quote:
Originally Posted by thtanner View Post
I still think it's a ground. Every time mine did that, it was one of the ground wires. (and it did it 3-4 times after I first got it.. had to keep tracking down the various ground cables, and using some loctite.)
the tach operates off the Front (#1) Cylinder.....

so yes, absolutely x2 on thTanners remedy.

...check/clean ALL connectors...

'86 VN750 13,700 mi -Stock
-Purchased 2008 w/8800mi
Replaced ALL Cables . Kuryakyn LED Voltmeter
SilverStar Ultra 9003/HB2 H4 Headlamp, Jardine Fwd Controls,
Iridiums DPR7EIX-9 & Wires, Tuxedo Mod, Coil Mod, P/U Sensor Mod, Fork Seals,
Splines Lubed - 11/4/2012 - MF AGM Battery
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Dampers went out @ 13+K !
After TOC MCCT's..... so amazingly quiet I discovered a rattling heat shield on my stock exhaust !
...have a vulcan good day!
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post #4 of 16 (permalink) Old 05-28-2014, 11:25 PM
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This sounds an awful lot like what happened to me right before my bike went out the other day. Mine turned out to be a couple of loose connections and a loose ground.

It's a bit of a pain but the best thing to do would be to carefully check over all of your electrical connections to make sure that nothing came loose.

If they aren't soldered on I would check the ring terminals to the battery to make sure that they are still tight as well.
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post #5 of 16 (permalink) Old 05-29-2014, 09:38 AM
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Make sure also your key is not in the "wiggled a bit to the left of 'on'" position.

I had an issue starting my bike - it wouldn't start with the key in the on position. I had to turn it slightly counterclockwise to get it to work. This slight counterclockwise position was giving me the same issue you seem to have.
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post #6 of 16 (permalink) Old 05-29-2014, 02:00 PM
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Quote:
Originally Posted by crowley1027 View Post
Make sure also your key is not in the "wiggled a bit to the left of 'on'" position.

I had an issue starting my bike - it wouldn't start with the key in the on position. I had to turn it slightly counterclockwise to get it to work. This slight counterclockwise position was giving me the same issue you seem to have.
I was just about to suggest removing the puck under the key tumbler and cleaning the contacts in it.
It sometimes cuts out completely, but has been known to also give intermittent issues and symptoms like a loose connections.
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post #7 of 16 (permalink) Old 05-29-2014, 02:53 PM
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clean all connections while doing this you may find the issue. there is a ground that goes to the engine. its on the back of it on the right side. use contact cleaner and 1000 grit sandpaper for connections held by a bolt. a nail file works good too. i used a welding tip cleaner set pretty much the same as a carb cleaning set on the harness connections. get some electrical grease to prevent more corrosion once cleaned.
good luck hope its something simple.

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tp stator
dampers
coil relay mod
other stuff not listed
mustang seat
motorcycle repair at a stealership 1 million bucks, repairs with the help of the Vulcan750 forum priceless.
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post #8 of 16 (permalink) Old 05-29-2014, 04:51 PM
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Try jumper cables to the battery from the car. If it runs like new, the battery is taking a dump. Had similar problem a week ago, ran great on the cables from the car, died when they were off. Replaced the battery and runs like new.
It may be the battery is shorting internally.
Bronson.

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post #9 of 16 (permalink) Old 05-29-2014, 05:01 PM Thread Starter
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Thanks to everyone for the, as usual, excellent advice and willingness to help out a fellow rider.

I have not yet put on enough miles to say with certainty that the issue has been resolved, but I think it has. I did not see any faulty connection/ground issues, but I did clean and re-seat the major ground points at the battery, frame and engine block. Also cleaned up the left side ignition coil wire connector tab for the black wire.

If all goes well in the next day or so, I will post a message to share my final conclusions. Suffice it to say this for now: if you don't usually get your bike wet while riding, you just might be surprised by what happens when you do!

Thanks again.
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post #10 of 16 (permalink) Old 05-29-2014, 05:55 PM
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hope you got it fixed. let us know the anticipation is killer lol

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2003 kaw vn 750 pushing 40,000 miles.
tp stator
dampers
coil relay mod
other stuff not listed
mustang seat
motorcycle repair at a stealership 1 million bucks, repairs with the help of the Vulcan750 forum priceless.
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