Author Topic: Help me narrow this down pls...  (Read 1951 times)

Offline boatdetective

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Help me narrow this down pls...
« on: May 16, 2015, 03:19:31 PM »
OK- so this is the littel V50.  NArrowed down problem to left cyl. not firing.

Background:
The bike has seen major going through and had been running just dandy. The problem showed up after the ignition crapped out and I just wired the bike up with a simple kill switch. At the same time, I changed out the throttle/start switch assembly. Aftermarket switch and Tarozzi throttle.  I have no idea how this might create an issue- but the problem started immediately after i did this project.

The ignition is a Dyna S with Dyna coils. I have tested them ten ways to Sunday. I sent the rotor assembly and sensors back to Dyna and everything checked out. Voltage to both coils is okey dokey (11.4VDC). Ohms OK.  Just because- I switched the coils from side to side and no change.

The problem is consistent right from startup (does not show up as bike warms up). I put a little test light in line with the plug wires and the light does not flicker on the left side.

Of course, plugs changed.  Plug wires changed (which i never asked for-nightmare with repairer who never figured this out). -On a side note: I do not know if these are "resistor" plug wires and do not know if that will be a problem.

Repair guy had removed the rotor, sensors, cleaned/lubed/reinstalled - nada 

Timing checked multiple times. Just because carbs gone through again and again.

Once again- I think I've got it narrowed down to ignition- one side is not firing off.  
Thoughts?  






« Last Edit: May 16, 2015, 03:43:16 PM by boatdetective »
Jonathan K
Marblehead, MA

1981 V50III "Gina"
2007 Griso 1100 "Bluto" (departed but not forgotten)
2003 EV "Lola" gone to the "Ridin' Realtor" in Peoria
2007 1200 Sport "Ginger"

"Who's the cat who won't cop out, when there's danger all about?"  -Isaac Hayes

Offline Monza-jockey

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Re: Help me narrow this down pls...
« Reply #1 on: May 16, 2015, 04:13:02 PM »
I had a bad plug cap; it was an NGK.

 I replaced it with non resistor caps as I'm running resistor Iridium plugs. Also 6mm non resistor wires. Everything works fine for me. just my $0.02 worth.
I don't always ride motorcycles, when I do,  I prefer  Moto Guzzi.

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1982 V50 Monza

Offline lucian

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Re: Help me narrow this down pls...
« Reply #2 on: May 16, 2015, 04:23:49 PM »
Did you try pulling both plugs, grounding both against the heads and cranking the starter with ignition on to actually see if both plugs are sparking? If so what color is the spark? And are they arcing to the electrode or off to the base rim? Sounds like your kill switch may be grounding one side out.

Offline boatdetective

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Re: Help me narrow this down pls...
« Reply #3 on: May 16, 2015, 05:56:19 PM »
You may be on to something. The left side does not spark at all. Please translate "your kill switch may be grounding one side out". I'm not cracking wise, I literally don't know what you mean. How can the kill switch affect one plug and not the other?
Jonathan K
Marblehead, MA

1981 V50III "Gina"
2007 Griso 1100 "Bluto" (departed but not forgotten)
2003 EV "Lola" gone to the "Ridin' Realtor" in Peoria
2007 1200 Sport "Ginger"

"Who's the cat who won't cop out, when there's danger all about?"  -Isaac Hayes

Wildguzzi.com

Re: Help me narrow this down pls...
« Reply #3 on: May 16, 2015, 05:56:19 PM »

Offline lucian

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Re: Help me narrow this down pls...
« Reply #4 on: May 16, 2015, 05:59:27 PM »
How did you wire in the new switch?

Offline Idontwantapickle

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Re: Help me narrow this down pls...
« Reply #5 on: May 16, 2015, 07:02:17 PM »
Disconnect the negative side of the coil (the side hooked to the Dyna) and attach a jumper wire. You stated that power is at the coils. Remove plug for that coil from engine and attach lead to it and set it on the engine to ground it. Turn on the ignition. Ground the other end of the lead attached to the negative side of coil to the engine. Then pull it away to break the circuit to the coil, repeat. Plug should spark each time the connection is broken. This is what the points or Dyna would normally be doing. If it sparks then the problem resides in the Dyna or the wiring to it. If it does not the there is either no power to the coil or coil, HT lead, cap or plug are defective.
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