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Discussion Starter #1
So what we have here is a failureto communicate somewhere. I have rode for years but never worked on these myself. The issue i am having is almost like a dead cylinder. This is a 2004 vtx1300. As far as i know everything is still factory. I took it to Rock Hill Powersports in SC and after 3 months and $1000 its still the same. I can pull the front right plug wire loose and increase the spark jump which seems to smooth out the engine. Where do we start to figure this out? Remember i am new at working on bikes.. Im a diesel mechanic.
Thanks
 

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I’d start with the common electrical ground at the front coil. Also common to have
Broken wires internally at the ECM... need to shake them around with the bike running.
Beyond that.....what’s the history of the bike. Sounds like you just got it.
You probably should have a conversation with the service manager if it’s still the same after a thousand bucks. Can you tell us what they did?
 

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Man I wish u the best of luck...I’m assuming u didnt get dinner...:mad:
 

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So what we have here is a failureto communicate somewhere. I have rode for years but never worked on these myself. The issue i am having is almost like a dead cylinder. This is a 2004 vtx1300. As far as i know everything is still factory. I took it to Rock Hill Powersports in SC and after 3 months and $1000 its still the same. I can pull the front right plug wire loose and increase the spark jump which seems to smooth out the engine.

Where do we start to figure this out?


Remember i am new at working on bikes.. Im a diesel mechanic.
Thanks
I would try swapping the coils.

Diesel mech...... Respect!
 

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A single coil on HV, spark plugs in a series arrangement on either end of coil. 32k to 36k ohms resistance.. Verify.. Like DD said ICM wires, the most forward ones, Green wire and/or the Black wire right at the connector..
 

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So what we have here is a failureto communicate somewhere. I have rode for years but never worked on these myself. The issue i am having is almost like a dead cylinder. This is a 2004 vtx1300. As far as i know everything is still factory. I took it to Rock Hill Powersports in SC and after 3 months and $1000 its still the same. I can pull the front right plug wire loose and increase the spark jump which seems to smooth out the engine. Where do we start to figure this out? Remember i am new at working on bikes.. Im a diesel mechanic.
Thanks
I'm assuming compression is good , and wondering if valves have ever been adjusted or gaps checked . as said there was isssue with coil ground losing connection at the coils and green and black wires breaking on the ICM on top of battery . wiggle on them with it running . Battery cable bolts tend to loosen over the riding season . I had a petcock issue once that made her backfire and or die . put a diaphragm in petcock to fix it . I'd check ohms on coil and wires too . new plugs ? Battery voltage ? Eo
 

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A single coil on HV, spark plugs in a series arrangement on either end of coil. 32k to 36k ohms resistance.. Verify.. Like DD said ICM wires, the most forward ones, Green wire and/or the Black wire right at the connector..
Been a while since I had my VTX.
I was thinking it had two 2 wire coils... I stand corrected, thanks.
 

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I had a very similar issue...turned out I was running on only 2 cylinders. Had done ground mod. Tried new plugs and coils known to be good. Turns out it was a couple of frayed wires leading to the rear coil (visible signs of scorching). Sometimes it's the easy thing. Sometimes....
 
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IGN coils pic updated. Will be added to Step by Step 1300 and 1800.
If cylinder heads were made of carbon fiber, than a wire
would have to be run from one spark plug shell to the other
to complete the high voltage current path.
 

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So what we have here is a failureto communicate somewhere. I have rode for years but never worked on these myself. The issue i am having is almost like a dead cylinder. This is a 2004 vtx1300. As far as i know everything is still factory. I took it to Rock Hill Powersports in SC and after 3 months and $1000 its still the same. I can pull the front right plug wire loose and increase the spark jump which seems to smooth out the engine. Where do we start to figure this out? Remember i am new at working on bikes.. Im a diesel mechanic.
Thanks
So what we have here is a failureto communicate somewhere. I have rode for years but never worked on these myself. The issue i am having is almost like a dead cylinder. This is a 2004 vtx1300. As far as i know everything is still factory. I took it to Rock Hill Powersports in SC and after 3 months and $1000 its still the same. I can pull the front right plug wire loose and increase the spark jump which seems to smooth out the engine. Where do we start to figure this out? Remember i am new at working on bikes.. Im a diesel mechanic.
Thanks
Your bike has 2 plugs per cylinder. Clean your spark plugs. I have a 2005 VTX 1300. This happens to me, the front cylinder goes dead. I remove the 2 front spark plugs and clean them in a media plaster. That seems to fix the problem for my bike.
 

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Discussion Starter #11
Thank you for the replies.. Ok so this work was done on 11-6-2019..
Replaced 4 spark plugs
3 ft of sparkplug wire
2 base manifold
1 insulator, carb
1 coil, ignition
1 petcock assembly
1 tube B vacuum
1 bulk hose
1 tube fuel
I bought this bike about 3 years ago. Started having issues last year finally took it to the shop and got screwed. I'll attach photos of service order.
171271
171272
171273
 

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Discussion Starter #12
Your bike has 2 plugs per cylinder. Clean your spark plugs. I have a 2005 VTX 1300. This happens to me, the front cylinder goes dead. I remove the 2 front spark plugs and clean them in a media plaster. That seems to fix the problem for my bike.
Has new plugs and coils. Only rode it twice since i got it got.
I had a very similar issue...turned out I was running on only 2 cylinders. Had done ground mod. Tried new plugs and coils known to be good. Turns out it was a couple of frayed wires leading to the rear coil (visible signs of scorching). Sometimes it's the easy thing. Sometimes....
Tried the wiggle test at ecm no change. Wiggled front coil seemed to help but not 100% sure. Where is the common electrical ground located. My coils are bolted to plastic.
 

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Your bike has 2 plugs per cylinder. Clean your spark plugs. I have a 2005 VTX 1300. This happens to me, the front cylinder goes dead. I remove the 2 front spark plugs and clean them in a media plaster. That seems to fix the problem for my bike.
If you use the choke to start your bike it will foul the plugs quickly. I try to not use my choke at all. I just had the problem and cleaning the plugs fixed the problem for me. Clean the plugs, before you start tearing everything apart.
 

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Discussion Starter #14
I'm assuming compression is good , and wondering if valves have ever been adjusted or gaps checked . as said there was isssue with coil ground losing connection at the coils and green and black wires breaking on the ICM on top of battery . wiggle on them with it running . Battery cable bolts tend to loosen over the riding season . I had a petcock issue once that made her backfire and or die . put a diaphragm in petcock to fix it . I'd check ohms on coil and wires too . new plugs ? Battery voltage ? Eo
Added pics of all work that was completed in november. As far as valves i do not know if an adjustment has ever been done. Trying to figure out where the common ground is...
 

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Discussion Starter #15
If you use the choke to start your bike it will foul the plugs quickly. I try to not use my choke at all. I just had the problem and cleaning the plugs fixed the problem for me. Clean the plugs, before you start tearing everything apart.
Ok I'll try that next.. I have been using the choke to try and get it to run.. Was flooding out real bad.
 

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The Rear coil is mounted on plastic. It does not need a Ground.
The Front Ign coil is partially covered by the fuel tank on the left front side.
It is bolted to the frame, main purpose is to Ground the Master Green
wire from the Yellow 14 pin connector that has all the Green ground wires on it.
About 10 Greens and 1 Black.

Backfire from carb???
Explosions from exhaust pipes??

Any air leak at the exhaust pipe can provide enough air(oxygen) to create an explosion in the pipe.

Carb slide valve diaphragm if it has tears or splits can create explosions.

Choke aka Starter Enrichment - I use mine on every cold start.
NEVER fouled spark plugs.

What cylinder appears to be dead?? Temp near exhaust port or pipe??

Loose battery connections, ICM wires, vacuum hoses, usual stuff.
Do a fuel flow test, pull fuel hose off petcock, apply vacuum to vac port, should have a good stream of fuel coming out.
Could be a loose connector in the headlight.
You can verify continuity from the ICM to the most Forward wires
that tend to break most often: Black wire and/or Green wire.
 
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Discussion Starter #18
The Rear coil is mounted on plastic. It does not need a Ground.
The Front Ign coil is partially covered by the fuel tank on the left front side.
It is bolted to the frame, main purpose is to Ground the Master Green
wire from the Yellow 14 pin connector that has all the Green ground wires on it.
About 10 Greens and 1 Black.

Backfire from carb???
Explosions from exhaust pipes??

Any air leak at the exhaust pipe can provide enough air(oxygen) to create an explosion in the pipe.

Carb slide valve diaphragm if it has tears or splits can create explosions.

Choke aka Starter Enrichment - I use mine on every cold start.
NEVER fouled spark plugs.

What cylinder appears to be dead?? Temp near exhaust port or pipe??

Loose battery connections, ICM wires, vacuum hoses, usual stuff.
Do a fuel flow test, pull fuel hose off petcock, apply vacuum to vac port, should have a good stream of fuel coming out.
Could be a loose connector in the headlight.
You can verify continuity from the ICM to the most Forward wires
that tend to break most often: Black wire and/or Green wire.
Front cylinder seems to be dead most of the time. Exhaust temp is cold on front and hot on back. I do have a short in a front side light. Will be checking wiring and that ground at the front coil when i get home. Vacuum lines are new and tight. Backfire is a combonation of exhaust and carb. Mainly exhaust.
 

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If air gets into exhaust pipe it will ignite the residual a/f and pop or explosion result.
If ICM wire is intermittently broken it can create backfires/misfires.
Check coil terminals, wire.
Black/White is +12v, Blue/Yellow from ICM pulses Ground to energize the IGN coil.
The official test is a peak voltage test, just a diode and a capacitor.
100v peak at cranking per Honda. I have measured much higher when running.
 

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