SE coil- Bad?

Derekm · #1 16th May 2006

I was given a spare SE coil for the bike when I bought it. PO said he ran it for a while and it ran fine, but would trip the CE light. Said the dealer checked the part number and resistances on the coil and everything was OK, but he decided not to run it ( He only wanted it cause it was black instead of stock grey). Today I was going through some stuff and ran across it and decided to check it out.

So now I can't find the part number on HD website (P/N-31698-98), or any SE coil for my 1200S for that matter, but obviously it is for an "S" model with dual-plug heads.

Besides that, when I check it using resistances from the FS manual, I get continuity across 1-4 & 3-2 which should be 10-12k ohms ( I think).

Anybody know what could be up? I was thinking of selling it, but if it has a chance of being dead, well then that's not gonna happen.

Thanks- Derek

Just thought of something- Could it be a Buell coil and not be on the HD website? Going to check it now......

jssport · #2 16th May 2006

the 1200s SE coil is no longer made or available, only the stock unit can be purchased

same as the 1200s SE ignition module that allows over 5200rpm operation

btw, 1200s coils blow up very easily, you must unplug the 3-wire "boat" connector to properly turn engine over without firing, if you just unplug the cap on the plugs, the coil can be damaged.

sportsterrific · #3 16th May 2006

That ignition would be nice. I keep bumping redline on my 1200s. Seen a few 1200S coils and ignition modules on ebay.

chrishajer · #4 16th May 2006

The 31698-98 coil is still available from HD dealers. True, it's obsolete, but a dealer can order it from the company they sold all their slow moving inventory to. Just give the dealership parts dude the number, and have him check around. They can find it. Just find yourself a good parts person.

-- Chris

Derekm · #5 17th May 2006

Well, I guess that's good- I've got some rare parts

.

For you guys that know something about these things- what do you make of the resistance (or lack of) between terminals 1-4 and 3-2? Is this a sign that the PO may have fried it while on the bike?

jssport · #6 18th May 2006

The resistance between 1-4 and/or 2-3 should be 11.7K and 12.7K ohms.

You will get continuity because it is the same wire, however you should still get the above mentioned range on a multimeter set to measure resistance. If it is low (0-1k) the coil is shorted, infinite and it has broken or "opened". Both indicate the coil is bad, toss it.

If it seems good check the primary coils, this the the 3 wire "boat" connector. measure resistance between the center lead and the outside leads. Each should be .4-.6 ohms. More or less indicates a short or an open.

The question in my head is what is the right range for a SE coil. It would seem that something must be different for it to step up the voltage over the stock unit. Wether it is the number of turns or the diameter of the wire, this would result in "slightly different" resistance.

You want more info? OK....

Our 1200s's were the first to use these low impedence input coils, they later became std on the twin cams in a dual (vs-4) version. The twin cam coils can be used on the stock 1200s ignition if you ever choose to switch to single plug heads, just get a std xl coil bracket.

The 1200s coils are in series not parallel. The arc on the spark plug jumps from the inside electrode out on one, then from the outside to the center electrode on the other spark plug.

The SE coil initially seemed to be giving false error codes to the original 98 engine lamp in the tach, causing calls to dealers and the factory. This resulted in the 99 models coming without that "engine diagnostic" lamp in the new tach. I guess that fixed that. Originally the modules and coil could be purchased seperatetly but by revision 3.5 the came as a set that had been tested at the factory.

I don't think they ever grasped the fact that most problems were blown coils from running them without a load because of not disconnecting the input lead.

JimS
owner of:
2 good stock coils
1 bad stock coil
1 bad SE coil
1 98 stock module
1 99 stock module
1 se 6800 module
1 se 7500 module

Derekm · #7 18th May 2006

Thanks, thats good stuff! Unfortunately I think my se coil is toast, but I've got a stocker on it now and it works well enough.

I also have the 6800rpm se module and I really like it. The bike seems to be pulling well beyond the stock limit and is fun to ride up there when on a good road.

Thanks jssport