GENERAL FACTS
What do the letters stand for? Multiple Spark Discharge. It's a patented design that fires the spark plug multiple times every time the unit is triggered.
What will a MSD unit do for me?
Easier starts, more horsepower, better throttle response are the
expected results from a MSD capacitive discharge ignition - whether it's
an analog or digital system.
Why do I need more ignition power?
With the multiple spark discharge of a MSD ignition, it is finally
possible to completely ignite the air/fuel mixture in the cylinder -
giving you more horsepower. In a 2-stroke engine this is important. When
you suddenly give the engine "the gas" after idling, the engine will
bog down. This is the result of a weak stock ignition trying to burn off
the excess fuel that has built up in the cylinder. The stock ignition's
weak spark can't do the job. A MSD ignition has a hotter spark to start
with, and along with the multiple spark discharge, a MSD ignition will
thoroughly ignite the air/fuel mixture.
Spark Plug GapWith
a MSD Ignition you can run a wider spark plug gap than you would be
able to with a stock ignition. The MSD Ignition has a higher voltage
output and can jump the spark plug gap easier. As an example, if you
normally would run a .028 inch gap on your spark plug with a stock
ignition, you could run a .032-.034 inch gap with a MSD Ignition. There
are variables that will affect the gap size: the higher the compression -
the smaller the gap; the hotter the output of the ignition - the larger
the gap, etc.
What does "Total Loss" mean?
The flywheel no longer charges the battery. Usually the flywheel on a
total loss system has been replaced with a light weight aluminum
flywheel, without the charging magnets. Quicker acceleration is the main
advantage of a total loss system since you have lightened the moving
mass on the end of the crankshaft. The drawback is that you have to keep
an eye on the charge level of the battery - and how often depends on
how many times you use the starter (a big drain on the battery) plus how
long you are out on the water. Figure about 4 to 6 hours of ride time
starting off with a fully charged battery that has a 17 amp-hour rating -
depending on how many times you use the starter.
How do I find Top Dead Center(TDC)?
TDC is where the piston has reached its highest point in the cylinder.
It is the foundation to accurate timing. To find TDC, remove the spark
plug and use a plunger depth gauge to judge where TDC is. If you don't
have a depth gauge, place a screwdriver thru the spark plug hole until
the screwdriver rests on top of the piston. Turn the flywheel until the
screwdriver reaches its highest point, make a reference mark on the
flywheel and a reference point on the case. Then reverse the rotation of
the flywheel, allowing the screwdriver to lower down and come back up
again to its highest point. Make another reference mark on the flywheel.
If the two points match up - consider yourself lucky because you have
an accurate crank/connecting rod/piston assembly. If the two marks don't
match up, pick the point exactly between your two reference marks
(using the points closest together) - this is true TDC.
Analog vs. Digital Ignitions
Why the switch from analog to digital? The main advantages of a digital
ignition are: accurate timing; smaller ignition box size; full access
to the timing curve via dip switches; you can change the initial timing
at the MSD box electronically instead of moving the trigger around
physically; reliability (because there are fewer components to fail).
Can I get replacement instruction sheets? Yes. You can download instructions in the download section.
We can also mail them, or fax them to you. All we need to know is the
part number of the unit that you need replacement instructions for, and
we'll be happy to get them to you.
What is RF noise?
RF Noise stands for Radio Frequency noise. It is generated by spark
plugs when they spark, and on motorcycles by points. RF noise causes CD
ignitions to run erratically if they aren't shielded. A good way to
lower RF noise is to use a good set of RF suppression spark plug wires -
like MSD's 8.5 mm Super Conductor Wire or our 8mm Heli-Core wire. The
Super Conductor uses a special winding procedure with a ferro magnetic
impregnated center core that is an effective RF suppression spark plug
wire. In addition to using good spark plug wires, make sure that all
grounds are good and clean. If you still have RF problems, shielding the
ignition or moving it away from the RF source helps reduce
interference.
NO SPARK
Why don't I have spark? In most cases, it is usually due to a bad ground or no ground at all. Check all
connections. Here are a few things you could check: make sure the
ground wire is securely attached; that there is no paint under the
ground wire; the connectors have good secure connections; there are no
breaks in the wires; the battery is fully charged. Check for a bad
on/off switch to the ignition box. You could have a bad coil, and
switching it out for a coil that you know is good is the fastest way to
determine whether a coil is the culprit. Perhaps you have a bad triggering device.
Check it by removing the spark plugs (leaving the spark plug wires on),
and grounding them to the engine. Next: clip the two green trigger
wires coming out of the engine, and repeatedly touch the 2 wires going
to the ignition box together. Make sure the power to your ignition is
on. You should get a spark, or the L.E.D. (if equipped on your MSD box)
should light. If you get a spark, then the trigger is bad. If the L.E.D.
light turns on and there is no spark - then either you have a bad coil, a bad spark plug wire(s), or a bad spark plug(s).
REV LIMITERS
How does a Rev Limiter work?
A rev limiter does just what its name implies: it limits the revolution
speed of the engine. Why is this important? If you have the throttle
wide open on a watercraft and it comes out of the water, there is no
load on the engine. The engine will dangerously zoom up in speed past
its intended design and physical limits, possibly destroying itself. On a
motorcycle if you have the throttle wide open and miss a shift, the
same thing happens: a rapid increase in rpm's, possibly destroying
parts. A rev limiter is placed in the electronic circuitry that prevents
the engine from over-reving. At a pre-set rpm - say 7,000 rpm - the rev
limiter engages. Once the engine reaches 7,000 rpm, it interrupts the
signal to the coil, alternating on/off, slowing the firing sequence, and
preventing the engine from rapidly shooting up in rpms. Factory
rev-limiters are generally set at low rpm levels. If you have modified
your engine you may not notice any performance gains due to the stock
rev limiter's low rpm limit, which is why you would use a MSD Rev
Limiter. With our units you can set the point, where you want the rev
limiter to limit the engine's rpm.
Does a Rev Limiter automatically make my engine go faster?
Only if the engine is currently being held back by the factory rev
limiter. You never want to set the rev limiter's rpm cut off point too
high - serious engine damage could occur.
TWO STROKE WATER INJECTION
How does water injection work?
Water is injected into the expansion chamber at specific rpm levels,
this alters the sonic wave in the pipe. The water molecules directly
affect the sonic wave properties, modifying back pressure deflection.
You want the water to be injected at low to mid range rpms, and to be
tapered off before your engine enters your upper rpm levels (leaving
enough water to prevent any rubber couplers from melting). At 3,000 rpm
the MSD Pulse Width Modulated (PWM) Switch turns on the water, by gently
pulsing it on and off, then (at a rpm you preset) it will flow a steady
stream of water. At a user preset rpm, the water starts pulsating on
& off again, as the rpm rise, the volume of water decreases until
the shutoff point is reached. There is no abrupt changes in power with
the MSD PWM Switch...as though you are hitting a pipes' powerband. With
the water gently pulsing on and off, instead of suddenly on and then
suddenly off you avoid the unwanted pipe "power band" effect.
Will it help top end? The
primary benefits are low and mid range power increases. To also gain top
end performance you could restrict the water flow in your pipe's stock
cooling system, and use the MSD PWM switch to not only tune the pipe,
but cool it at the same time. This is tricky because if you restrict the
stock water cooling too much, you could melt the rubber couplers.
DIGITAL IGNITION
How Do I Program It?
Whether for motorcycle use or watercraft use, each MSD Digital Ignition
is optimized for the particular vehicle. Obviously, a full technical
explanation of correct ignition timing for each individual engine would
take up too much room here. A broad overview of how to arrive at a timing curve is shown in the guide below.
FACTOR
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ADVANCE FOR
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RETARD FOR
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Cylinder Pressure
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Low
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High
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Engine RPM
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Low
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High
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Energy of Ignition
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Low
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High
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Fuel Octane
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High
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Low
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Mixture (Fuel/Air)
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Rich
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Lean
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Temperature
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Cool
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Hot
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Combustion Turbulence
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Low
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High
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Load
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Light
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Heavy
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General Tuning Tips:
• You need to have all
systems operating properly before you can fine tune your ignition
system. Here are a few tuning tips for watercraft and motorcycles.
• Reading spark plugs is an important element of tuning. Take a good look at the insulator's ceramic coloring.
• A good light tan/gray color is perfect.
• If the plug is black with wet or dry deposits, it's usually a fouling
problem. Heavy dry deposits might indicate too rich a carburetor(s), too
cold a plug heat range, low compression, timing is retarded too far, or
the gap is too big.
• If the deposits are wet, it could be due to a blown head gasket, bad rings or valvetrain problems, or too rich a carb setting.
• Silver specs, black specs, melting, or breakage at the firing tip on the plug is a sign of detonation.
• A white or real light plug color could possibly mean the carb(s) is too lean.
• Spark plug color is only accurate when checked after a high speed run,
engine turned off at max rpm, and craft glided in with engine still
off. No idling allowed!
• Each cylinder should be fine tuned as a separate motor/pipe/carb
combination. Not all carb screws on multiple carb set ups will
necessarily be adjusted the same - or jets necessarily the same size.
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