I have a 1993 FatBoy with 95K miles. Bike has a Dyna 2000 single fire ignition, crane single fire coils. Lately the bike hasn't been running well. Bike would cut-out while riding, start-up again and you would hear an explosion out the exhaust. Sometimes the bike will just cut-out completely, and I would hit the starter button, but the bike would not start. The strange thing is that the lights would still be on. I've pulled the gas tanks, checked/yanked on the wiring and even took apart the kill switch, but everything looked good.
This weekend, I was completely frustrated since I wanted to get this ride back on the road running strong. What I noticed was the following:
I start the bike in the driveway, and if I jiggle the ignition switch, the bike will stop, but the lights stay on. Hmmmmm maybe now I'm getting somewhere. I took the ignition switch apart, and I do see some small gouges/dimples on the contact roller. Could this be what's causing the engine to shutdown? Is this a typical part that wears out? I've attached a picture, unfortunately it's a little blurry.

 

Exact same problem on my '86 Softie. I find I could be riding and it will miss and splutter and if I wiggle ign. switch will get a huge backfire, why the backfire, I don't know.

Try it on the "lights off" position to see if it runs ok.

I was also thinking of one of these:
http://www.ebay.com/itm/HEAVY-DUTY-E...ht_2190wt_1270

Seems like good value and I have dealt with Al's before and found him good.

TC

 

The backfire is easy to explain, and I did in another thread. Here's what happens; when the ignition is cut off, even for an instant, the carb still feeds mixture to the engine, only now it doesn't ignite (no spark) and passes out into the header, unburned. Stock Evos use a "waste spark" ignition that fires the plugs on the compression stroke, and again on the exhaust stroke. When the ignition comes back on, the waste spark touches off the unburned gas in the headers, causing the backfire.

I converted to one of those "electronic" switches a few years back and I'm completely happy with it.

 

Thanks for that Uncle G. Well explained and makes perfect sense.

Since posting my first reply have ordered switch, but being in Ireland it will be a week or so before delivery.

TC

 

I cleaned mine up with some sandpaper and it has been working well for the last few years. Since the contacts are exposed to the air you can't grease them or they will collect dirt.

I suspect the new style switches can't be easily repaired/cleaned when they fail like the original but they probably stay clean longer.

 

The last stock switch I had failed when one of the conical rivet contact points sheared and broke off, leaving me with a dead position. Fortunately, it was the accessory position. That's why I decided to try something different.

 

Had something similar, started manifesting itself as carb flooding funny enough. Besides the switch being a bit worn, it turned out to be the grey wire (coils), broken inside the insulation, near the switch.

 

Just wanted to post a follow-up to the issue/problem I posted about a few years ago. I've been tired of looking at the FatBoy sitting in the corner of my garage for the last couple of years, plus I miss riding it. This past weekend I decided to take a look and get it road worthy again. Spent a considerable amount of time searching and reading old HDForum posts and gathering as much information and knowledge as possible. Replaced the following parts:

1. Ignition Switch. Old switch seemed to be worn out.
2. Starter relay (Napa replacement Part Number: AR143)
3. 30 amp circuit breaker (Napa replacement Part Number: 782-3107)
4. All (3) 15 amp circuit breakers (Napa replacement Part Number: 782-3002)
5. New battery (Autozone Duralast Gold ETX20L)

The battery that was in the bike has been kept on a Battery Tender, but it did not have enough power to turn over the starter. I estimate the battery was about 12 years old. Date code on removed battery was 4/2003. Didn't want to spend the money for a HD battery. The physical size of the Autozone battery was slightly smaller which led to a bit of play in the rubber strap that secures the battery. I had some Styrofoam packing material, which I folded up and placed between the battery and the rubber strap.

The starter relay I replaced was the original one on the bike. It tested out fine, but I thought that it was a good idea to replace it since I was having intermittent problems.

I read about other people having similar intermittent issues and the problems seemed to point to issues with circuit breakers, especially ones that have been in service for awhile. The replacement circuit breakers I purchased at Napa have slightly longer studs than the original Harley ones. After I installed the circuit breakers and attached the connectors, I coated the connections and studs with dielectric grease.

I cleaned all the wire connectors that connect to the circuit breakers.

When I was going over all the wiring, I found that the grey wire on the ignition circuit breaker inside the connector was badly frayed. I spliced on a slightly longer wire with a new connector.

I'm happy to say that all my electrical gremlins seem to be history!
Bike starts easily and runs great.

Basic Engine Build Information
Air cleaner: Screaming Eagle
Cam: Andrews EV-27
Exhaust: Python II
Carburetor: stock Keihin 40mm CV
Main Needle - N65C (27094-88 or sportster 88 XLH needle)
Main Jet - 165 (27116-88)
Pilot Jet - 45 (27170-89)
Ignition: Dynatek Dyna 2000-HD1
Coil: Crane Single Fire Performance Ignition Coil (8-3001)
Pushrods: Crane Timesaver Pushrods (4-0030)
Rocker Arms: Crane Bushing Roller Tip Rocker Arms (4-1015)
Heads: port/polish/shave, 3-angle valve job

Did I say the bike is running (and sounding) great???

I missed cruising the backroads on this machine. It obviously rides much differently than my road sofa (2011 Ultra). My first stop after getting it back together was the gas station to fill up. I remove both gas caps and begin filling the tanks. The gas jockey (NJ is only full service, but they all typically allow you to fill your own bike), walks over, looks the bike up and down and says.... now that is cool.......