Hi Guys. I have a stock 1988 FLHS with the only add on being drag pipes. (previous owner.) The bike misses when the lights are turned on, even more if the fog lights are on. It has had this problem for the 2 months that I have owned it, however it would run fine after thoroughly warmed up. Now it misses and carries on whenever lights are on. Any thoughts? I do have my service and parts manual, but I'm no pro mechanic. Going to a mechanic is not an option due to being stubborn and wanting to fix it myself. Any thoughts appreciated.

 

Do an electrical system check per the sticky. If that is OK, then it is likely a bad ground connection or a dirty/corroded connector somewhere. Check the voltage at the coil positive with the lights on and off. Oh, and on your bike, the lights should be on all the time, unless the wiring was hacked. Or are you talking about some other lights?

 

When the government mandated that headlights be on all the time, Harley simply added a jumper wire on the ignition switch...many people removed it so the two positions on the switch actually worked like the older bikes...gotta be low voltage...do the tests he suggests.

 

My bike has an "on" position and a "lights" position, it also has a acess. position that kills the bike, but mine is without the fairing or associated Police add- ons.
I have made a copy of the charging system sticky and I will follow it and post if I get stuck or solve my problem... Thanks.

 

Yes, an On and Lights positions. From the factory, they are jumpered together, so there is no difference in operation between the 2 positions. Someone cut the jumper at some time in the past.

 

Since that switch has been hacked, it could also be a dirty ignition switch, which is a known issue. While your digging through this, assuming you pass the electrical system tests, and there's a difference at the coil, check the voltage at the coil with the switch in the Lights position and the headlight disconnected at the plug.

 

My 1990 FLHS, bought new, came with the lights switched on on the Lights position only, not jumpered, so it is possible there are variations. They are still that way!

Dr H has the definitive Sticky on our charging systems, so follow that, however I would first go over all your main power connections, clean, coat with dialectic grease and check again. Especially check both ends of the battery ground cable, also the ground strap under the trans.

 

U.S. spec since the late 70's had the jumper, Tups. Dunno about them foreign markets.

 

By the time I bought my Evo H-D did acknowledge there was a World outside North America, but not when I bought my original shovel! That also had separate lights in 1974, but told me to ride on the right.......

 

I made a point of disconnecting the jumper lead between the main running lights and basic lighting / power for accesories to operate. I prefer to start my bike without the load of all the lighting pulling on the battery at the same time. I also will run for a period of time without the addition of the running lights / headlights to return a full charge back to my battery. I do make sure my headlights are operating when riding in conditions where they will help me to be seen in traffic.

Are there additional aftermarket lighting on your bike? Maybe a heavy duty upgraded headlight or additional running / brake lights?

Odds are good that your charging system is overtaxed and beginning to fail. As the voltage output is dropping there is less voltage to properly run the ignition system.

Open up your derby cover and take a whiff of the odor. If it smells like a burning transformer instead of oil odds are good your stator is frying out and dying.

There's a sticky thread at the top of this forum to help with trouble shooting the recharging system. Give that a try.