Ignitions

Ignition systems tend to frighten a lot of folks off but they are really not that hard to understand.
(The problem is keeping all the different ones straight)

This is just a quick outline of some of the basics.   

Terms - Understanding what is what

History - Understanding when is what

Operation - Understanding how is what

Ignition timing - understanding how to do it

Terms

•Points - a set of electrical contacts used to interrupt current flow to the ignition coil.

           •Coil - (also called a spark coil) is an induction coil in an ignition system which transforms a battery's 12 volts to the thousands of volts needed to spark the spark plugs.

          •Single Fire - Spark plugs fire independently and only at the correct time. "Unfortunately, CCI (Custom Chrome Inc.) has taken it upon themselves to reverse the definitions of dual and single fire when referring to their proprietary Rev-Tech ignition products. Rev-Tech dual fire systems are really single fire systems, and vice versa.
Single-fire will not provide more HP but will give better idle, easier starting and better throttle response off idle to 3K RPM. A 'dual' coil is required as it is actually two coils in one.

        •Dual Fire - In the stock HD ignition system (pre-1999), both spark plugs fire at the same time, so one plug is firing when it's piston is at BTDC of it's compression stroke while the other cylinder is also firing on its upward moving exhaust stroke, "wasting" a spark and igniting unspent gases while firing against the engine's rotation. This causes a noticeable and unnecessary vibration and makes for harder starting. As of the 1999 model year, all stock H-Ds bigtwins have gone to single fire.

        •Dual Plug - this is a popular Shovelhead modification but I have also seen it in Evos, a second spark plug is installed in each head, on the side opposite the stock plug. This is a total waste of time as you are only covering up an inefficient combustion problem.

    •Rev Limiter - The ignition retards the timing at a preset RPM to prevent the motor from revving higher than desired. This is a Good Thing, as high revs will prematurely wear a motor and very high revs will find you saying interesting phrases like "Oh fuck, what was that !?!" and "Who do I know with a pickup truck".

 

A little history

Harley-Davidson has used many ignitions over the years. In the early days (pre-1979) an advanceable Points & Condenser system was used. Advancing and retarding the ignition was operated manually by twisting the left handgrip (pre-1965). A dual points single fire system was developed and installed in the early sixties by the Harley dealers. The factory developed the parts, but would not install them, the dealer had to.

In 1965 automatic advance was developed, utilizing a set of weights that by centrifugal force at around 1500RPM would turn the points cam, advancing the timing. While the auto advance was very dependable, it was also high maintenance. Points and condensers had to be periodically replaced and the advance weights had to be kept lubricated.

In late 1979 H-D stepped into the electronic age with an ignition from "Presto-lite" that eliminated the points and condenser, but still used the mechanical advance weights. This was a good move, but to put it mildly, it was a "Piece O' Shit" system. It was not unusual for folks to remove this system and install the earlier points ignition system. For many years after this nobody trusted H-D electronic ignitions. 1980 saw an upgrade to the Magnavox ignition system, but it really wasn't much better.

In 1982 The V-fire ignition was developed. This system was primarily contained in a black box more commonly known as an ignition module with a separate cam sensor plate. No more advance weights because the module advanced the timing electronically. Triggered by a rotor cup and a hall effect transducer at the cam sensor plate, this system required no maintenance. Due to the different ignition requirements between the Sportster and the heavier Touring bikes, a Vacuum Operated Electric Switch (VOES) handled changing the advance curve. Under heavy load conditions or idle the ignition is retarded, advancing at higher RPMs. This ignition soon proved to be very reliable but was often plagued with problems associated with heat. 

In 2001 the cam sensor was eliminated and the ignition timing was completely handled by the Crank Position Sensor (CKP).

All Harley-Davidson electronic ignitions that came direct from the factory prior to 1999 were "Dual Fire" (firing both spark plugs at the same time). One coil triggers two spark plugs, one producing power on the compression stroke, and the other plug firing during the exhaust stroke. 

Crane, Dyna, Compufire & Spyke are just a few of many companies that offer both single fire and dual fire ignitions. H-D itself has gone to the single fire type ignition on today’s Twin Cams. Each brand of ignition has its advantages and disadvantages. A Duel fire system is the same type that has been around forever and if you select one of these types, the 1979-1998 coil will usually work. But a single fire ignition has the advantage of better starting and reduced low speed vibration. These advantages are distinct and very noticeable. Its drawbacks are the increased initial cost and the requirement of a different type coil be purchased. 

For folks with a generator bottom end that want to upgrade to electronic ignitions, there are several aftermarket companies that have electronic replacement for that old points circuit breaker but a warning to those folks doing replicas or restorations, they don't look stock.




I have installed many different ignition systems and there is very little difference between most.
As far as overall performance, reliability and ease of installation, I would have to say that I like the Crane HI-4 Single Fire system the best.

 

Theory and Operation

Points Ignition:

When the ignition switch (key switch) is on you have power to the points even though the engine is not turning over. When the points are closed current 'charges' the primary coil creating a magnetic field, this is called "Dwell". When the points open, breaking current flow though the primary coil, the magnetic field collapses energizing the secondary coil and firing the spark plugs. You can open the points with a screwdriver, they will spark the spark plugs every time you open them.
When checking for no spark, bear in mind that most times it is caused by dirt or corrosion on the contact surface of the ignition points.   Ignition coils rarely fail, and if a condenser is bad you will get a tit built up on one of the point contacts and a pit on the other.  Also check that the pivot for the points is not sticking, so they do not close properly.
      There should be a small amount of grease on the cam lobe that opens the points to prevent the rubbing block from being worn down  Most points will work gapped at about 16 to 18 thousandths (old school folks use a matchbook cover, it's close to the right thickness).

Ignition Coil:

A coil is exactly what it's name implies and nothing more. It's just a coil of wire wrapped around an iron core. Actually it's two coils of wire, the primary (wire terminal to wire terminal) and the secondary (spark plug wire outlet to spark plug wire outlet).
 Test for continuity between terminals and test for continuity between outlets to find if the internal wire is broken. The only other test possible is to replace with a "known-good" coil and see if it solves the problem.
An ignition coil for electronic ignitions can be used with a points ignition but a points coil cannot be used for electronic. Single fire coils can only be used for single fire ignitions and they can use nothing else.

Electronic ignition components:

Electronic ignition serve the same purpose as a points ignition except they do it electronically with no mechanical moving parts. 
Electronic ignition components are solid state and are not serviceable. The only testing procedure is to replace with "known-good" components and see if it solves the problem.


Ignition Timing

  Static timing:

 On the flywheel and (viewed through the timing hole or window' of the engine case) there will be a set of marks for timing. An advance mark, and a top dead center mark (see your service manual for your year and model).
  Points -  When turning the engine in the direction of rotation, the points should just crack open as the advance mark lines up with the window in the case (Be sure that mechanical advance weights are open to full advance.

Electronic Carbureted - Many electronic ignitions have a L.E.D. light to indicate static timing. With the TOP DEAD CENTER flywheel mark in the window (ignition switch on, engine not running), turn the cam sensor plate counter clockwise until the light goes OUT.

EFI (injected) - Timing is controlled and/or adjusted by the ECM, timing may not be altered by the customer.

Dynamic timing:

Dynamic (or strobe light) timing is not an optional step in the timing process, it is the final step. Static timing is only intended to be the initial timing step to get the timing close enough to start the engine to dynamic time it (gets you in the ballpark).
You will never get the dynamic timing right if you cannot see the flywheel mark through  the oil! It is often helpful to paint the mark. With the engine off, remove the spark plugs and rotate the engine so the mark is visible in the hole and use carb or brake cleaner to degrease it and then use a bright color paint on the flywheel mark (fingernail polish works well, dries quickly and comes with it's own convenient little brush in the cap).
Sometimes it is possible to time the ignition with the hole open but you will spray oil all over your timing light, bike, shop and your eyes (making it difficult to see anything very well for several hours), I don't recommend it.
You will need a clear plastic timing 'Window' to screw into the timing hole. It is vital that you choose the correct timing window, the short ones do not work - don't even buy one. Why don't they work? Because you have to have a window that will screw all the way in until it touches the flywheel. It can be difficult to tell if the window has bottomed against the flywheel or if it has just bound up in the threads so put a small dot of grease on the end of the window and then watch for it to spread out when it touches the flywheel. Once the window touches the flywheel, back it off 1/4 turn, this allows the window to scrape the engine oil out of your way and see the mark while the engine is running. Connect your timing light to a battery source (does not have to be the one in the bike) and connect the pickup to the front cylinder spark plug wire. The ignition timing must be set at full advance so start and run the engine @ or above 1500 RPM, the advance timing mark should be in the window.