Well, I'm sitting in my shop, looking out at about 20 feet of snow, wondering what to write about. Whose even thinking about motorcycles? This month, I decided to write about ignition systems.

Let's start by explaining what it does. The ignition system is probably the most important part of the bike because it is the most likely to leave you stranded. It is the system that is responsible for lighting the mixture at the proper time. The first type of system is the magneto, which was used when a bike didn't have a battery because a mag doesn't need power to operate. You don't see them used to much because there are many more advanced options. The second type would be a points-type ignition which was used for a long time and is still some people's choice due to it's simplicity. It used battery voltage and when the point set is opened and closed it charges the ignition coil. The last kind is electronic, which is the most popular. It uses a pickup off the cam to trigger an electronic pulse which charges the coil. There are two styles of electronic ignitions, single fire and dual fire. The difference is in the way they fire the cylinders. Dual fire will fire both cylinders at the same time, but only one cylinder is on compression stroke. The other spark is a wasted spark, which means it really does nothing. A single fire system, fires each cylinder by itself. This is done by having two pickups on the cam, one for each cylinder.

Stock Harley's come with a dual fire system which sends a signal to a module which controls the timing. The module has an input from the Voes valve which will retard the timing when the bike is under an extreme load. This is to prevent pinging. The stock system works well, but many upgrades are available.

Most of your street applications can be handled with a module replacement. The module controls most of the areas affected by performance changes. The tow most important areas to look for are the rev limiter and advance curves. Most good aftermarket modules will do. I recommend a Dyna, but that's just an opinion.