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post #1 of 33 (permalink) Old 05-23-2014, 04:59 PM Thread Starter
1987 Vulan VN750-A
 
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Starting problems

My Vulcan is in the shop, and the techs seem to be completely dumbfounded as to why it isn't starting. Great spark, carbs are working perfectly, and it cranks like nobodies business. What else could it be?
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post #2 of 33 (permalink) Old 05-23-2014, 05:02 PM
1986 VN750
 
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Did this just start happening, or after a service? Does it stumble @ all or just crank?

Pickup coils backwards?

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]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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post #3 of 33 (permalink) Old 05-23-2014, 05:14 PM Thread Starter
1987 Vulan VN750-A
 
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Ah yes, a little background. I purchased a 2001 VN750 back in August for cheap, then it turned out the guy didn't have a title. In preparing the motorcycle, I had the carbs cleaned and got everything running perfectly. The guy never came through with the title.

Saved up a bit, and bought a 1986 VN750 (the one they are working on now). It had been sitting since 2008. Traded my other carbs off of my 2001, replaced the gas tank (had a little rust in it). It has shockingly good ignition, and carbs are running good, and kicks over like a mule, but won't catch and run.

Oh, and it will after like 10 turns backfire, then go back to turning over. They checked the valves on both to make sure ever thing was good, and everything is within tolerance.

Last edited by ro35647; 05-23-2014 at 05:19 PM.
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post #4 of 33 (permalink) Old 05-23-2014, 05:22 PM
1986 VN750
 
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Ah, one thing with older wiring (the 86) is power can be lost in the wiring harness, causing weak spark. It'll be 'decent' spark, but not good enough.

My bike would barely get started.. I swapped to iridium plugs, and an AGM battery (much better on the older wiring as well) and she ran amazingly well.

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]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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post #5 of 33 (permalink) Old 05-23-2014, 05:24 PM
..have a vulcan good day!
 
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Quote:
Originally Posted by thtanner View Post
Did this just start happening, or after a service? Does it stumble @ all or just crank?

Pickup coils backwards?
Double check this.....wires get swapped ?


'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
Additional Flashing LED Brake Light on Trunk
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 #6 of 33 (permalink) Old 05-23-2014, 05:32 PM
..have a vulcan good day!
 
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Quote:
Originally Posted by thtanner View Post
Ah, one thing with older wiring (the 86) is power can be lost in the wiring harness, causing weak spark. It'll be 'decent' spark, but not good enough.
On my '86, I avoided potential problems in this area....performed the Coil Relay Mod.

(Battery +12 v thru a standard relay directly to the coils...relay activated via original rear cylinder 12V supply coil wire.)


'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
Additional Flashing LED Brake Light on Trunk
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!

Last edited by WilliamTech; 05-23-2014 at 05:35 PM.
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post #7 of 33 (permalink) Old 05-23-2014, 05:43 PM Thread Starter
1987 Vulan VN750-A
 
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Already installed a AGM battery.
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post #8 of 33 (permalink) Old 05-23-2014, 05:44 PM Thread Starter
1987 Vulan VN750-A
 
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Quote:
On my '86, I avoided potential problems in this area....performed the Coil Relay Mod.

(Battery +12 v thru a standard relay directly to the coils...relay activated via original rear cylinder 12V supply coil wire.)


Yea, I read about that too, but they insist I have GREAT spark.

Last edited by ro35647; 05-23-2014 at 05:51 PM. Reason: adding quote
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post #9 of 33 (permalink) Old 05-23-2014, 05:47 PM Thread Starter
1987 Vulan VN750-A
 
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Quote:
Originally Posted by WilliamTech View Post
Double check this.....wires get swapped ?

How would that even be possible? One is under the seat and one under the cover plate on the left side of the neck?
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post #10 of 33 (permalink) Old 05-23-2014, 06:18 PM
..have a vulcan good day!
 
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Quote:
Originally Posted by ro35647 View Post
How would that even be possible? One is under the seat and one under the cover plate on the left side of the neck?
Not the Spark Plug cylinder coils.....

Pick -Up Coils ! .... the proper name ? ? ?
The coils behind the Stator Cover.
Wires come out together from the upper portion of stator cover...

If coils are swapped (or the wired connections swapped), each cylinder will receive it's spark at the wrong time (timing way off - will not run).

hth

'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
Additional Flashing LED Brake Light on Trunk
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!

Last edited by WilliamTech; 05-23-2014 at 06:21 PM.
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