Megafire module vs points

[Terry Sullivan]

Has anybody tested the timing with a Megafire module ( points eliminator )?
I installed one on a Clinton E65 and it starts right up. I also have one on an MC-10. Just wondering what advance I now have and whether it will run better or worse than points. I know the E65 would normally have 27 degrees BTDC with points.
I suppose I could bolt a degree wheel to the PTO and see what a timing light says, but I was hoping somebody else had already gone to the trouble.
Russ? Have you done it?

Terry

[Russ Smith]

NO........but they work fine on an E65 or converted saw.

[Terry Sullivan]

A mutual friend in Oregon thought that the module mught have robbed the low end grunt from his MC-6.

[Gordon Duax]

All these moduals (Mega-fire, Novatron, Adom, Yamaha TCI) opperate on the voltage rise created by the magnets by the flywheel passing the coil.
Timing can be adjusted 2 ways, by advancing or retarding the flywheel with stepped key,
or in the case of the Mac, a plus 5 flywheel, or if your engine has it, an adjustable timing plate.
And by what distance you put the coil from the flywheel.
As little as .005" clearance change can alter the timing by several degrees.

When my son was running Jr. sprtsman many years ago, I had mapped timing on the TCI, and all the different Adoms that were available at that time.
Then I played with coil/flywheel gap, and documented that also.
It was a big advantage when traveling to different tracks, and weather conditions,
all I had to do is look at what we had done at that track during past races, and say, OK, put this modual on, and set the gap here.

By the way, not all Mac +5 flywheels are at 5 degrees.
I once went through about 30 flywheels, and the magnet location will vary +/- 3 degrees from what they are supposed to be.
They were all over the place.
Keep that in mind when someone says "only run the +5" or "only run the standard", as the 2 just may have the exact same timing, depending on how far out of spec. it is.

[Terry Sullivan]

Thanks for the info Gordon.
I probably won't do much in the way of changing the timing. I'm getting too old to go fast.
I am curious to know how the timing changes just by bolting the module in and not changing anything else.

Were you actually measuring the timing changes or just recording better or worse lap times?

Terry

[Rob Voska]

Don't the different modules have different curves? I mapped a stock Yamaha years ago and it was advanced at low RPM and retarded at high RPM. Changing the air gap seemed to changed the location of the curve not the curve. Also if gap is to tight you will bounce the flywheel off the oils legs.......

[Gordon Duax]

Were you actually measuring the timing changes or just recording better or worse lap times?

Terry

I was actually taking timing light readings off the engine while it was on a dyno when I mapped them.
The Atom 'white' was the worst, it actually went into severe retard past about 8,000.
I believe it was for a briggs or something.
The yellow, and orange were the best, purple wasn't too bad.
I haven't tried any the newer versions of the aluminum case units, like the mega-fire.

[Terry Sullivan]

** I did not do well in college electronics courses, so my assumptions may be worthless **

I can't find any specs on exactly how they work and perform.
I'm thinking that the Megafire triggers on a voltage change and has no additional logic that will modify the timing as the RPM changes.
Any change in the timing throughout the RPM range might be a result of the quality of the basic design or the quality of the internal components. Some components are better quality than others and some may be more susceptible to heat and vibration.
Maybe the Atom White module ran out of team above 8000?

Again, I won't be expecting optimum performance from my engines. I'm sure they will be faster than the driver.
Just wondering if being lazy and using the Megafire is foolish.

[Rob Voska]

The coil and magnet create the spark, the module "times" that spark. Correct?

[Scott Kneisel]

I have not seen a schematic of any of these modules but I am an electrical engineer and can pretty much speculate how they work.

The module is connected between ground and the primary of the coil. As the flywheel magnets approach the coil lamination, a voltage is induced in the coil. The module senses this voltage and when it reaches a certain level it breaks the ground (same as the points) using a power transistor and the secondary side of the coil discharges thru the spark plug. Due to tolerance variation in cheap electronic components, that voltage trigger value could be all over the place. These things were made for lawnmowers and snow blowers so timing probably was not the biggest consideration in their design.

I guess just as many have said in this post, the only way to change where the module fires the coil is by changing the relationship between the flywheel magnets and the coil lamination. And then I think the only way to see where the coil is firing is by using a timing light and some kind of timing graduations and a TDC mark. As Terry has already warned me...make sure that the timing light will work with a 2 cycle engine so that it fires at each spark.

I prefer points & condenser because of their versatility but I guess if you are not concerned about optimal performance, these things are just the ticket. Gee, I wonder how you could get an engine into maverick spark with one of these modules.

Have fun you guys,
Scott