Things you should know when using or installing
an electric start.
Several electric starters are available for
the Rotax line of engines. The only one that I recommend is the Rotax
more information click here.
The starter should be used with a minimum
20 amp hour battery. The battery leads should be no more than 5 feet
in length. and a separate ground cable must be run to the engine
from the airframe, to ensure proper ground.
Several owners have reported burning up
their engine wiring system when they failed to follow instructions
and properly ground the engine.
This is caused by the single small ground
wire that is grounded to the coil mounting bolts, melting in the
wiring harness, fusing wires together when the engine is cranked.
This wire is not large enough to carry the kind of current
When using an electric start on a Rotax
aircraft engine TWO grounds are required, one going from the engine
to the airframe and another going from the engine to the negative
side of the battery.
These ground cables should be about the
same diameter as that used on a GOOD set of booster cables, that you
would use to jump start your car. (In many cases that is what pilots
Other pilots have reported failure of the
starter solenoid supplied with the Rotax starter. It would appear
that this failure is caused by improper mounting of the solenoid.
The solenoid should be mounted in free air away from vibrations, and
as close to the engine as possible.
I don't recommend using the solenoid
that is USUALLY supplied with the starter from Rotax. Instead drop
into your local Canadian Tire store or a good automotive supply
center and get a solenoid for a Ford car, or truck. It can usually
be found on the fender. I have never had one of these fail and it
can be purchased locally.
Another reported problem with the starter
is the failure of the studs used to secure the starter to the ring
gear housing. If your starter is mounted in any position other than
the 6 o'clock position failure of the stud will result in the two
big washers found on the end of the stud falling into the magneto.
The washers are then picked up by the magnets with catastrophic
results. Usually destroying the crankcases and ignition system.
||9 - Stud 841 950
|13 - O ring 850 585
|14 - O ring 230 260
To help prevent this it is suggested that
the starter only be mounted in the six o'clock position. If the
studs break in this position the washers would fall harmlessly to
However I also suggest that you run a bead
of silicone from one
end of each stud to the other end, including over the casing. This
way if the stud fails you still have the washers, and ALL of the
little rubber shock absorbers that are on the studs [about $60 worth
If you have had to replace the studs, or
have done other work which requires removal of the starter motor,
remember that there is suppose to be a TWO milli meter gap between
the starter and ring gear housing.
On the old specs the lock nut part#842-O3O on the end of the
retaining stud that goes through the starter cover was to be torqued
to 195 inch lbs. This spec's was incorrect. If torqued to 195 inch
lbs contact could take place between the starter cover and starter
flange, resulting in the stud fracturing The correct spec's are as
follows and have been corrected in the newer parts manuals. Tighten
this lock nut to obtain a .040" (forty thousandth of an inch)
between the starter flange and the starter cover. This allows the
starter to move and absorb the vibrations that normally occur
during engine and aircraft operation.
Rotax has also updated the ring gear on the
electric start the new gears are slightly thicker. The older gears
were found to crack and fail around the gear teeth. Rotax also
updated the spacer used to support the ring gear. The older spacers
only had three support fingers while the new supports have five
Some owners have reported finding their
ring gear housing breaking at the point where the stud runs through
the housing. This can usually be traced to a succession of hard
landings, or to the starter striking something on the airframe
The only other problem I have heard of is
slow cranking starters, or starters that will no longer crank. This
problem can be traced to the starter brushes. One brush can be
replaced easily The other requires the purchase
of the complete plate assembly.
Brush holder with springs
Carbon brush with screw
While not an electric start problem, the
use of the proper regulator rectifier on the 582/618 can lead to the
battery going flat, and the electric start not working.
While the points equipped can use the CHEAPER regulator
rectifier the 503/582/618 Ducati ignition engines require the use of the more expensive
regulator. The reason for this is that the the NEW 503/582/618 put
out considerably more charging power than the old 377/447/503's
This translates to more HEAT in the
regulator/rectifier. The more expensive regulator/rectifier is
larger and has aluminum fins which are used to dissipate this heat.
Single Phase Regulator
(Used on 377/447/503/532 with points ignition)