1998 sportster 1200 problem

[RussosRide]

Hey guys, I’m new to this but I’m in the process of building a chopper out of my 1998 sportster. I bought it stock a month or so ago and had 0 problems. But I rode it down to SC and when I got there I started to get a problem I couldn’t figure out.
It would randomly sound like the motor is bogging down if that makes sense. I would lose almost all power to the belt and wouldn’t be able to go over about 50-60mph. So far I’ve cleaned the carb. Replaced the petcock from a vacuum to a gravity. Replaced the fuel line, bought new plugs, put in a new coil and wires, did a compression test to where i had 120-125psi in each cylinder, and checked out the ignition. Everything is fine but I’ve narrowed it down to where I noticed the right side of the coil isn’t producing spark.
Is the coil my main problem for not getting power randomly? Or is it something more? Also how could I fix the coil problem?
Thanks!
-Russo

[TriNortchopz]

when the problem started, was it still stock, or pertly chopped? Did you measure voltage at the coil? What make/model coil ya got? what make model ignition ya got?
check all wires for shorting or grounding? All ground wire connections clean and tight?
and, what carb ya got?

[JBinNC]

On the standard HD dual fire coil, the secondary terminals (for the plug wires) are connected to each end of the secondary winding. When the coil is triggered, a spark is produced at both terminals. If you have one side with no spark, the wire or plug is bad, or the coil has a short to ground internally. If you are checking spark in the usual way, with the plugs laying on the heads, and you are getting no spark at one plug, replace the plugs first and retest, then replace the wire and retest. If it fails both, the coil may be bad, even if new.
If the coil, wires, and plugs test good, your problem is probably in the pickup or module.

Jim

[RussosRide]

So I’ve done some more trouble shooting and found that I had connected the wires to the single fire coil the wrong way. The left side of the coil isn’t producing spark. I’ve tested a bunch of different things to figure out if it’s the plug, the wire, or just the coil and figured out that the pink wire that runs from the ignition to the coil has either shorted out or is disconnected somewhere. So now I have to trace the wire throughout the bike and figure out my problem. Thank you for all the help though Jim, and TriNortChopz

[JBinNC]

If you have a stock ignition, it is dual fire, and it doesn't matter which side of the coil is pos. 12V and which is the trigger wire.
On your stock wiring harness, the pink wire should be the tachometer trigger wire, and can be left disconnected for diagnostic purposes.

If you have an aftermarket ignition, which you failed to mention, disregard the above.

Jim

[RussosRide]

This updates been long overdue. But for some reason I bought a new coil and wires and it fixed the problem right away. Since then I took the bike to Gypsy Run and have been ripping it around no problemo ever since. Thanks for all the help and quick tips. Keep on choppin’ dudes

[farmall]

Glad ya fixed it!