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Deleted member 12676
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I finally got hold of a Lightning CDI to test it against a Jaguar Performance CDI on the bench. Below is a graph showing the timing curve difference.
The spark strength of the two is the same, using the same high voltage coil. The main difference is that the Jaguar CDI retards the timing at a higher rate than the Lightning above mid range RPM. How/why the Lightning designer thought it unnecessary to give a normal retard curve is beyond me, but it's in my favor. If you will look at motorcycle ignition curves you will see that the final timing is always close to 10 degrees BTDC at peak RPM and that the downward slope towards that starts early. Take a look at these graphs to see what I'm talking about:
The RM curve to watch is the full throttle one since motorized engines at peak RPM are always at full throttle. The RM peaks at around 9200RPM, typical of 250cc motocrossers.
In conclusion it looks like the Lightning is too retarded at around 3000RPM, which limits power, and too advanced at high RPM, very similar to the standard CDI, which limits power and rpm and causes vibration. Now I see why he never has made available the timing curve.
I'm sure now Huffy will huff and puff like a big bad wolf and say his makes more power, blah blah blah without giving a good technical explanation of why. Soon JNMotors will have dyno results for a modified engine using both CDIs so we can all see the actual power difference. But apart from power there are two other things to consider; vibration and reliability. More retarded timing at high RPM lessens the vibration from these engines. Why? It counters the imbalance. The flywheels have too little metal removed at the counter-balance holes. Reliability is improved by retarding high RPM ignition because having the ignition happen too early means the peak combustion pressure will be happening more around top dead center instead of around 10-15 degrees after top dead center. That early peak means much more pressure on the bearings which wears them out early.
The spark strength of the two is the same, using the same high voltage coil. The main difference is that the Jaguar CDI retards the timing at a higher rate than the Lightning above mid range RPM. How/why the Lightning designer thought it unnecessary to give a normal retard curve is beyond me, but it's in my favor. If you will look at motorcycle ignition curves you will see that the final timing is always close to 10 degrees BTDC at peak RPM and that the downward slope towards that starts early. Take a look at these graphs to see what I'm talking about:
The RM curve to watch is the full throttle one since motorized engines at peak RPM are always at full throttle. The RM peaks at around 9200RPM, typical of 250cc motocrossers.
In conclusion it looks like the Lightning is too retarded at around 3000RPM, which limits power, and too advanced at high RPM, very similar to the standard CDI, which limits power and rpm and causes vibration. Now I see why he never has made available the timing curve.
I'm sure now Huffy will huff and puff like a big bad wolf and say his makes more power, blah blah blah without giving a good technical explanation of why. Soon JNMotors will have dyno results for a modified engine using both CDIs so we can all see the actual power difference. But apart from power there are two other things to consider; vibration and reliability. More retarded timing at high RPM lessens the vibration from these engines. Why? It counters the imbalance. The flywheels have too little metal removed at the counter-balance holes. Reliability is improved by retarding high RPM ignition because having the ignition happen too early means the peak combustion pressure will be happening more around top dead center instead of around 10-15 degrees after top dead center. That early peak means much more pressure on the bearings which wears them out early.
