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Anyone in central Fl could help with this mod??
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This seems pretty straight forward, but I have one question. Instead of the 3 way splice between the relay and the coils, couldn't you go from relay to back coil to front, with there being hot in and out together in the spade to the rear coil? Or bring both front and rear to the relay and make the junction in that spade instead? It seems the three way joint is an unnecessary point of potential failure.
1991 VN750, purchased 5/5/15, 9092 miles
Senior Member
Note- if you are having firing issues or hard starting issues after a while after doing the mod, check your connection points. I found corrosion on my positive terminal that stopped my bike from cranking. It would turn over but wouldn't crank.
Grace and Peace to you!
Richard
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thanks bro for this post . such a great work , you have explained us so well .

I have a question here. If the wire for the original rear coil is being used to trigger the relay, wouldn?t that mean that all of the plugs are only getting spark when the ignitor box is sending signal for the rear coil to fire?
- "Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats."
'92 VN750
AGM battery, Iridium Spark plugs, Repaired/upgraded wiring per Mcinturff method, RLU removed, Repaired shift linkage, Exhaust baffles removed, Black ISO grips installed, installed SH775 R/R, Ignition coil relay mod, replaced stator housing.
Future projects: whatever it takes to keep riding
Currently working on: Light bar, LED upgrades, Dash cleanup/paint
Quote:
Originally Posted by TR_Irish
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I have a question here. If the wire for the original rear coil is being used to trigger the relay, wouldn?t that mean that all of the plugs are only getting spark when the ignitor box is sending signal for the rear coil to fire?
1992 US-nonCA * tuxedo mod * r/r relocated
Vulcan slang for newcomers
Service Manual Download
Wiring Diagram + annotations * still undergoing revisions, but still more useful than the generic one. Let me know if you find mistakes or think something additional should be added
Quote:
Originally Posted by Thorn
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This mod does not cause the new relay to turn on/off each time a coil fires, but rather provides a more direct path from the battery to the coils. You're cutting the wire from the killswitch to the coils and using that old voltage (weak because it passes through ignition and kill switch) and using it to switch strong voltage to the coils from the battery. The coils have two inputs. One solid voltage (now from the relay) on red wire, and one pulsed input (from the ignitor box, controlling the timing of the spark, untouched by this mod) on dark green and black wires, one for each coil.
- "Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats."
'92 VN750
AGM battery, Iridium Spark plugs, Repaired/upgraded wiring per Mcinturff method, RLU removed, Repaired shift linkage, Exhaust baffles removed, Black ISO grips installed, installed SH775 R/R, Ignition coil relay mod, replaced stator housing.
Future projects: whatever it takes to keep riding
Currently working on: Light bar, LED upgrades, Dash cleanup/paint
Ok, figured out that it doesn't matter which wire you put on which post of the coil.
I did mine a little differently by using a five pin relay and connecting each coil to its own pin of the relay (both pins 87 on the relay) and seems to work great. Spark is incredibly improved on the front cylinder, unfortunately didn't resolve my rear cylinder no spark issue like I had hoped it would. Problem is that it isn't geting the signal voltage to the other connector on the coil. It's unrelated to this mod, but I've gotta track down the issue either between the pickup and igniter box, or between the igniter box and the ignition coil. Or it IS the igniter box. Here we go again.....
I did mine a little differently by using a five pin relay and connecting each coil to its own pin of the relay (both pins 87 on the relay) and seems to work great. Spark is incredibly improved on the front cylinder, unfortunately didn't resolve my rear cylinder no spark issue like I had hoped it would. Problem is that it isn't geting the signal voltage to the other connector on the coil. It's unrelated to this mod, but I've gotta track down the issue either between the pickup and igniter box, or between the igniter box and the ignition coil. Or it IS the igniter box. Here we go again.....
- "Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats."
'92 VN750
AGM battery, Iridium Spark plugs, Repaired/upgraded wiring per Mcinturff method, RLU removed, Repaired shift linkage, Exhaust baffles removed, Black ISO grips installed, installed SH775 R/R, Ignition coil relay mod, replaced stator housing.
Future projects: whatever it takes to keep riding
Currently working on: Light bar, LED upgrades, Dash cleanup/paint
I think these machines run on whats called a wasted spark so the plugs will spark on every stroke hence( wasted spark) mean compression and exhaust stroke
Vn 750 A2 1986 rebuilt engine, crank shaft, half casing,shell bearings,con rods,rear cylinder head,oil pump,water pump ,(had ceased bearing rusted up),tie bar upgrade,clutch basket drilled,front cylinder cam chains,toc springs,stator,shaved, rectifier,agm battery,solenoid ,starter motor (used) re-spray ongoing.

Last edited by JETHRO; 10-11-2017 at 12:40 PM. Reason: make plainer
My '93 starts much better with the new (sealed) battery...if it aint broke,dont fix it!!
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