How do I install a dual coil setup?

Z

ZR440

New Member
Hello,

To introduce myself, my name is Kirk and I have been a member here for about a year. Although I do not have a big dog chopper, I do have a swift bar chopper, and thought it may benefit to be a member of this forum, for technical chopper info. if ever needed. I am in the middle of searching for a coil replacement for my bike. Being somewhat of a back yard mechanic, I want to do a two coil install on my bike. For a swift bar chopper, it is darn near impossible to find a wiring diagram, due to the company out of business and very limited info. on the internet. And I don't want to take it to a shop, and pay a ton of money, if I can do the work myself. I currently have a 3 ohm crane single fire, dual coil. It is mounted behind a "cheesy" swift coil cover that I believe does nothing for heat dissipation. That is my reason for looking at an exposed coil set-up. When I came across forum member MTpockets post & photos of his coil set-up, I immediately began researching. I am looking to purchase a similar bracket & two 3 ohm coils as he has done.

Now for my question, again I am a novice here, and if I can't figure it out, I will have to take it to a mechanic. But........I have 4 wires going to my single fire, dual coil. I have narrowed down the wires and figured out 3 of them going to the coil

blue wire = front cylinder
yellow wire = rear cylinder
white wire = "+" battery

Then I have a green wire that I can't figure out it's purpose. It attaches to the front cylinder pole with the blue wire. Any idea what this wire may do?

Lastly, I am assuming I will need to split the white wire/"+" battery, to go to each separate coil to supply power. Correct?

If I haven't thoroughly bored you with my issue, I am wondering if someone could explain a bit about a two coil hookup.

Thank you so much for your time.
 
BroadBand

BroadBand

Since late 60's
A quick search of the www brings up an interesting LINK that you may want to study.

Depending on your set-up & equipment, one diagram shows it not used on a Crane H4. Or could be as simple as a tach feed.

Check it out before putting on power so as not to fry it.

I am sure some others will chip in here before too long. Let us know what type of electrics you are using...

:flag:
 
V

V

Guru
Trace the green wire to see were its destinnation is may be as Broadband mentioned a RPM feed. You didn't mention the engine or year of your bike but I know some later model Swifts had the 117 cu in motor as well. Any aftermarket coil set up that will fit a Big Dog should fit your bike as well.

Couple of items that have been rub into are:

The two allen head bolts mounting the coil/ motor mount bracket could be longer. These have come loose in the past and a the soultion was longer bolts

The bolt at the top of the motor mount has come loose as well. Deping on what type of bolt you got make sure it is torqued properly and it would'nt hurt to use a bit of red locktite.

On any set up you get. You might do a mock up especialy if it s a 2 pc set up. Bolt on the top mount first. Then the bottom mount to the engine. You most likely find that you will need a spacer for the top mount to line it up with the bottom bracket.

If you get a one pc set up bolt it to the engine and you will most likely see that you will need a spcer at the top bolt/mount. and or a longer bolt.
 
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