Fire It Up
A long time ago, someone said, "If mechanical innovations kept pace with electronic innovations, an automobile would cost $2000." While this sounds ridiculous, it's not far from the truth. In the past 20 years, we have witnessed incredible advancements in the design and production of many electronic items. Quite often, newly designed systems are obsolete by the time factories gear up for production. A good example of these innovations is the change in electronic ignitions. I remember when tuning an auto or motorcycle equipped with breaker points had to be done routinely every 2500 miles. Then came capacity discharge ignitions which used several triggering systems. These worked much better than distributors equipped with mechanical points; however, the major drawback was the astronomical cost for such an ignition. Today, thanks to American ingenuity, competition, and the free competitive market we enjoy in this country we have products of exceptional quality and advanced technology. Also, these products come reasonably priced, which opened the door for applications such as watercraft, motorcycles, and other small engines.
Combustion begins at the positive electrode of the spark plug. It is very important to select the correct plug for any given application because if neglected, performance suffers. Maladjustment of spark plug gap as little as 0.002" can cause a loss of mph! Why? Because the gap between electrodes controls combustion temperature to some extent and if your ignition is weak to begin with, combustion will not occur as it should. This causes loss of power. A common mistake most people make is not using a torque wrench when installing plugs. Most riders use Popeye strength when tightening plugs, which causes stress at the electrodes and could lead to misfiring. Below is a list of recommended torque for various plug diameters: 10 mm - 7 ft/lbs, 12 mm - 10 ft/lbs, 14 mm - 14ft/lbs, 18 mm - 18 ft/lbs.
Selection of the proper plug heat range can make a big difference in performance. If the plug is too hot, you can blow a hole in the top of the piston. If the plug is too cold, the engine will never develop full power. My advice is to study plug design and heat range info from the charts and books that plug manufacturers can provide to you. The reason for studying plugs is simple: By accurately reading plug condition, you can determine what is happening in the combustion chamber and you can make horsepower increases by selecting the proper plug for your application. Note: This rull applies to quality racing fuel, must pump fuell is very dirty which makes plug reading vertualy imposible. The lower limit for plug operating temperature is 700 degrees Fahrenheit at the tip. At this temperature the plug will burn off carbon deposits and stay clean. Go lower than this and you will foul your plugs. The high limit is 1700 degrees Fahrenheit. At this point it is possible to start preignition. The trick is to find that plug which will operate within the needs of a particular powerplant.
Please pay attention to this statement: Poor ignition will reduce horsepower. Also, a claim of a gain in horsepower due to some revolutionary plug design or ignition is false. Ignition does not contribute to horsepower. What a properly designed system will do is to deliver a strong pulse of energy at precisely the right time and interval in order to extract every drop of energy which is present in the combustion chamber. Why do we need to spend money for a fancy system such as a total loss ignition? Well, if you are happy with a stock 38 mph, save your money for a fancy paint job or something like that. But, if you are power hungry you need to adjust your ignition for the many variables present in your environment. For instance, a motor set up for maximum top end speed has different ignition needs than a hard-hitting mid-range motor. With the quality after market ignition system such as MSD you have the ability to change your ignition timing which cover many conditions. With this system you can control advance and retard, rate of advance, as well as maximum rpm. There are three two-prong cables which permit quick module changes right at the beach. The retard rate can be from 0, 1/2, 1, 1-1/2, 2, 2-1/2, 3, 4, and 5 degrees per 1000 rpm. What all this means is that we can chose what kind of power we want. For example, if you are a heavy rider your high speed retard will start at 4000 rpm using a 4 degree module. If the engine reaches 7000 rpm then we will have 4 degrees of retard at 5000 rpm, 8 degrees at 6000 rpm, and 12 degrees at 7000 rpm. Let's say the rider is lighter. We can reset the ignition to compensate for this difference. Start the retard at 5000 rpm using a 3 degree module. Then, at 6000 rpm you have 3 degrees retard, 7000 rpm has 6 degrees. This allows for a much more responsive machine. For all out race conditions. When you spend thousands on motor mods, it makes sense to ignite that precise air-fuel mixture at the correct time. The adjustability of the MSD system is wonderful because we are constantly making changes to compression ratios, pumps, impellers, plugs, fuels, rider weight and style, and by changing the ignition characteristics, we are able to capitalize on these changes.
Since the system demands precision, I decided to use my own technique just to double check the accuracy. Stock timing marks on the MSD flywheel are round dots spaced at 5 degree intervals and are 1/16 inch in diameter. Since 1 degree equals 0.044" flywheel rotation, I made very accurate markings at the 5 degree and 2-1/2 degree points from 0 to 40 degrees advance. To make the job easier, I marked the stator plate with reference points from A to F which gives me a neat way to make adjustments quickly and precisely when needed. After positioning of the pickup coil on the stator plate I selected a mid-range gap of 0. 075". MSD specs call for 0.050" to 0.094" clearance between magnets and pickup coil. After installing all components, timing began. First of all, if you are looking for accuracy, you must apply precision.
Since the spacing between points is 2-1/2 degrees, I had to make a very thin and precise reference point. I used 1/16" piano wire ground to a sharp point and it works just fine. The unique feature of this system is that you don't need a timing light. The saturation point of the pickup coil repeats itself within 1/2 degree each time. I did not tighten the flywheel to the crankshaft until everything was set up properly. Since the system begins firing 5 degrees ahead of TDC at idle in order to keep spark plugs clean, you must set up accordingly. I chose a firing point of 25 degrees so the static point was 30 degrees. I was amazed at how accurately this system works. If you can't see the lines very well you can listen for a strong cracking sound at the spark plugs by rotating the flywheel in the direction of rotation. The energy delivered by this system is astronomical. There is a very strong pulse at the plugs which is approximately lmm in diameter and can reach over 25mm! The MSD ignition draws 5OOmA when the system is not running and will not burn out the coil. The reason for the on/off switch is to protect from accidental starts, because this system starts immediately! At 5000 rpm the system draws 2.5 amps, and at full throttle 5 amps from your battery.
Words of wisdom: When working on your ignition, always ground out your plugs because ungrounded plugs can burn out the system. Also, make sure you've vented your engine compartment of fumes because the potential for explosion is great. Always have a fire extinguisher handy, you never know...
Once you've started the engine, you will notice an improvement in the idle characteristics. Testing was done on my X-2 with twin 44mm carbs and stroked crank. To begin with, I used the 5000 rpm chip and 5 degree retard chip which gave very little improvement. As I changed to 3, 2, and I degree, throttle response became much better and I gained 1 mph top speed. In the final setup, I liked the 5000 rpm chip and 2-1/2 degree retard module in my particular machine. We need to understand the reason for a strong ignition on our two-stroke engines. Automobile and street bike four-stroke motors can use hotter plugs and stay clean for a long time. A two-stroke motor works twice as hard as a four-stroke motor. Firstly, it fires twice as often and secondly, this nasty stuff called premix is thrown in the combustion chamber. Add this to an already weak stock ignition and the colder plugs we must use in race motors so that we don't blow up each time we ride, and you can see the need for a powerful system such as the MSD ignition. Also, engine modifications will place totally different demands on the ignition system. For instance, when power is increased without raising the rpm range, the spark must be retarded from stock settings. Then, if the engine's rpm range is increased and powerband is also raised, this requires a more advanced spark. Once again, the MSD system comes through like a champ.
Accurate reading of spark plugs is limited to a small group of very gifted people and you can be sure they are employed by the major plug manufacturers. They don't send these people to your local riding spot to evaluate your engine's performance. So, you must become your own "expert" at this mysterious art. You must remember that the only way to begin spark plug reading is to run your engine wide open and make sure your engine is at maximum temperature. After running full throttle, hit the kill switch and coast into shore. This will give you a true plug reading. Selecting the proper plugs is both time consuming and expensive if you err in the wrong direction. My advice is to start with colder plugs and work your way hotter. You know that the plug is too hot when the insulator is scorched white and has signs of blistering around the nose area. A too-lean mixture will also produce a white insulator, but it will not produce the blisters a too-hot plug will. Also, any sharp edges on new plugs which begin to appear rounded or melted is a warning sign that the piston is going to fail soon. A plug's heat range is selected correctly when they get hot enough to burn away oil and carbon and have dry, brown deposits on the insulators after a hard run.
Failure of the ignition system can cost you much grief and money if you can't figure out what has happened. Modern CDI ignitions use electronic retard and advance circuitry which does fail upon occasion. There is nothing you can do to prevent these failures except keep the engine compartment as dry and clean as possible. I know some racers that spend an entire season chasing after lost power or suffering constant seizures and spend hundreds of dollars on replacement parts when the problem is a CDI unit stuck in the full advance position. If you ask around as to the last time someone had their ignition checked by using a strobe light, the usual answer is "What is that???" I know for a fact that even reputable mechanics do not own or even use a timing light to inspect the advance system for proper operation. In fact, most dealers and shops don't even have the means or knowledge to troubleshoot electrical problems. The only way for them to fix your problem is to start replacing components until the problem is cured. This haphazard approach to troubleshooting can cost you $400-$600 in unnecessary part replacement. Most of the time, it's a simple fix that could have been found by proper troubleshooting.
As I mentioned above, advance and retard circuitry does fail on occasion. If it gets stuck in the retarded position, the worst that can happen to your motor will be a loss of horsepower. But, when the system gets stuck in full advance, be prepared for some bigtime trouble. Regardless of the type of ignition system used, the plug must fire at the correct time to provide good power and avoid engine damage. When it gets stuck in the advance position, the mechanical problems which follow can puzzle most mechanics. Engines start suffering seizures and the mechanic's "fix" to the problem is to bore out the cylinder and replace pistons and rings. When the engine seizes again later, they go out and even replace the crank. All this could be avoided if they would simply check the advance/retard on their CDI. There are other factors which influence advance and retard characteristics. For example, the burn rate of various fuels is different. Methanol burns slowly, therefore more advance is needed. Low octane fuel burns quickly and needs retarded ignition. An increase in compression ratio causes temperature changes which increases the rate of combustion and therefore needs more retard. A very rich mixture burns slowly, requiring more spark advance. Increased engine rpm promotes fuel atomization and results in smaller fuel particles which burn more rapidly; therefore, less advance is needed. Any modification that raises peak horsepower results in higher cylinder head temperatures. A hot fuel charge burnss more quickly so the advance must be reduced. An engine with a bell-shaped squash band head requires less advance in timing. Conversely, hemi heads and big-bore cylinders will require more advance. As you can see, there are too many variables for a stock ignition to handle; that's why the need for a system such as the MSD ignition is so great.
George Grabowski HPT Sport USA