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Ignition timing - disassembly
Points and condenser replacement
Ignition timing reassembly
Recoil - disassembly/reassembly
Carburetor - disassembly/reassembly
Ignition
Timing - Fan cover and recoil removal
Tools required
Flat screw driver
Flat screw driver
To remove the fan cover, carefully pluck the three retaining
clips from the holes holding them into the fan tower. Then gently pull outward on the
cover, until it is off.
Recoil removal
Tools required
ratchet
ratchet
10 mm deep reach socket
Before removing the recoil, unplug the ignition suppressor box
(note color of connecting wires) by gently pulling on the two wires at their connectors.
Remove the 4, 10 mm socket head bolts and washers that retain the recoil to the fan tower
housing. The recoil will now come free.
Inspection:
-Inspect the recoil housing for cracking around the center and where the recoil rope exits
the housing.
-Inspect for proper recoil return spring action
-Inspect the recoil rope for fraying.
-Inspect ignition suppressor box at attachment points for cracking.
Ignition timing - Fanbelt, fan, starter pulley
removal
Tools required
6 mm allen wrench
locking pin
plastic mallet
6 mm allen wrench
locking pin
plastic mallet
Procedure
Located behind the recoil starter assembly is the starter pulley
and fan pulley.To remove these lock the crankshaft by placing the locking pin (supplied
with the Rotax engine tool kit), into the fuel pump impulse hole. Then slowly turn the
engine over until it locks.
With the crankshaft locked use a 6mm allen wrench to remove the
3, retaining bolts. This allows the removal of the recoil cup and fan pulley.Once the cup
and fan pulley have been removed rotate the fan belt in the fan blades until it is off.
Inspection:
-Inspect the starter pulley cup for signs of wear or damage.
-Inspect the fan pulley for signs of wear or damage.
-Inspect the fan belt for signs of wear or cracking.
-Inspect retaining bolts and washers for damage.
Ignition timing - Magneto removal
Tools required
Magneto puller
30mm socket
3 bolts, proper length
Magneto puller
30mm socket
3 bolts, proper length
Procedure
Install the bottom half of the Rotax magneto puller
using the 3, bolts. To align the holes in the puller correctly, rotate the crankshaft.
Make sure the bolts are the proper length if they are too long they can do damage to
internal parts, too short and they will strip the threads from the hole. Position the
puller so that the puller extension locks into the top of the fan tower on the intake
manifold side, as per fig F - 08 b. Before tightening the bolts install the 30mm socket
into the inside of the puller to properly align it. With the socket in place, the bolts
snug, use a ratchet or Johnson bar to remove the magneto nut and washer.
Ignition timing - Magneto removal
Now install the internal puller, TIGHTEN IT FULLY, then
using a wrench screw the puller bolt in until the magneto breaks free. Then by hand pull
the magneto clear of the crankshaft and engine.
Inspection:
-Inspect the key way area for signs of wear.
-Inspect the interior of the magneto for foreign material.
-Inspect the crankshaft end for signs of wear.
-Inspect lockwasher and nut for signs of damage.
Ignition timing
Tools required:
Flat blade screw driver
Dial indicator
Buzz box or continuity light
Feeler gauges
Business card
4mm Allen wrench
Flat blade screw driver
Dial indicator
Buzz box or continuity light
Feeler gauges
Business card
4mm Allen wrench
Parts required:
grease for phenolic block assembly
Procedure
Before installing the fan tower it is first easier to
do the ignition timing. To check the timing, place your dial indicator into the spark plug
hole in the magneto cylinder. Connect your buzz box to ground and to the magneto side coil
wire. This is the blue on black wire. Turning the engine over clockwise to bring the
piston to top dead center. Zero the dial indicator. Turn the buzz box on. Now turn the
engine counter clockwise. The buzz box should indicate the ignition is firing at .086
before top dead center.
Ignition timing
Repeat for the PTO cylinder using the blue on red
wire.
If the timing is not coming in at .086 BTDC, center the stator plate on the two retaining
screws. Gap the points at .015 Install the dial indicator in the magneto cylinder spark
plug hole . Turn the engine over clockwise until the magneto piston is at top dead center.
Zero the dial indicator. Connect the buzz box to the blue on black wire. Turn the engine
counter clockwise and note the firing position.If the engine is firing too early move the
stator plate clockwise.If the engine is firing too late move the stator plate
counterclockwise.
To time the PTO side cylinder insert the dial indicator in PTO
spark plug hole. Turn the engine over clockwise and bring the PTO piston up to TDC. Zero
the gauge. Hook up the buzz box to the blue /red wires. Turn the engine over counter
clockwise and note the firing position. It should be .086 BTDC.If the points are firing
too early decrease the point gap on the PTO set of points. If the points are firing too
late increase the point gap on the PTO side points.
Points and condenser replacement-Stator unit
removal
Tools required
4 mm allen wrench
4 mm allen wrench
Procedure
For points and condenser replacement it is suggested that you
remove the lower coil by removing the three retaining bolts, disconnect the wiring from
the top of the both coils, disconnect the ground wire, remove the rubber grommet where the
wiring enters the crankcase halves. Now remove the two allen screws, washers, and lock
washers holding the stator plate to the crankcase halves. The stator unit will now come
free. Slowly pull the stator plate out while carefully pulling the wiring harness through
the crankcase hole. Once the wires are free, the stator unit can be completely removed
from the engine.
Inspection:
-Inspect stator unit for signs of wear or damage.
-Inspect points and condensers for signs of oil contamination.
-Inspect points for signs of wear.
-Inspect the coils for damage.
-Inspect the wiring for wear, cuts or pinching.
Points replacement
Tools required
Vice
6mm wrench
Pliers
Screw driver
Hammer
With the stator unit completely detached from the engine it is
now possible to remove the points and condensers.
Points removal
For points removal, disconnect the points wire from the top of
the condenser. Then with a blade screw driver remove the screw and lockwasher retaining
the points to the stator unit. The points should now come free.
Repeat for the other side.
Points installation
Reinstall points in reverse order, ensuring wiring is routed
correctly.Repeat for the other side.
Condenser removal
To remove the condensers, remove nut and lock washer from top of
condenser, remove the points and ignition wires. Remove the insulating cap. Turn the
stator plate upside down on the bench so that the condensers are facing down. Support the
plate so that it rests above the bench. Place a small socket onto the bottom of the
condenser, and with a hammer, gently tap. The condenser will now come out.
Condenser Installation
For condenser installation place the stator unit sideways in a
vice. Place a new condenser into the condenser hole in the stator unit. Run a bead of
Loctite 242 around condenser where it meets stator plate. Place a socket the same size as
the outside of the condenser on to the top of the condenser. Close the vice down on the
socket, pressing the condenser into the hole. Make sure the socket is straight. Stop when
the bottom of the condenser is flush with the bottom of the stator unit.
Repeat for the other side.
Install the insulator caps, wires, washers and nuts.
Ignition timing- Magneto installation
Tools required
Puller ring 876 080 (1)
Bolts 940 581 (2)
Torque wrench
30 mm socket
Puller ring 876 080 (1)
Bolts 940 581 (2)
Torque wrench
30 mm socket
Shop supplies
Loctite 242
Loctite 242
Procedure
Before installing the magneto, check to make sure that the screws
holding the stator unit, points and coils are tight and that no wires have been pinched or
cut during installation.
Carefully place the magneto onto the crankshaft magneto end,
aligning the magneto key way cut up with the crankshaft key . Install the lock washer onto
the crankshaft, with the locking points facing toward the nut. Install the nut. Install
the outer half of your magneto puller, (A) locking the extension arm (B) into the fan
tower. Make sure to use the proper length bolts! Before tightening down the bolts, install
your 30 mm socket onto the magneto nut. This will centre the puller. Snug up the bolts
using the 30 mm socket and a ft. lb torque wrench and torque the magneto nut to 65 foot
lbs.
Ignition timing - Fan pulley, recoil cup, fan
belt installation
Tools required :
6 mm allen wrench
Torque wrench
Crankshaft locking pin
6 mm allen wrench
Torque wrench
Crankshaft locking pin
Procedure
Prior to installing the fan pulley install the fan belt. Fit the
belt through one blade of the fan and rotate it until it is installed in the fan tower.
Position the belt into the lower fan pulley and then pull it down and into position on the
magneto. Align the three holes. Install the recoil cup. Install the three allen head bolts
and lock washers.Install the locking pin into the impulse hole and lock the crank. Torque
the 3, allen bolts in two stages to 195 inch lbs.Remove the locking pin.
Check the belt tension.
Ignition timing -Fan belt adjustment
Reinstall the fan. After fan adjustment replace excess as per
update. install lock washer and install nut. Lock fan using fan fixation tool. Snug up
nut. Remove fan fixation tool. Spin engine over several revolutions, Install fan fixation
tool and torque nut to 45 ft lbs.
Ignition timing Recoil and wiring installation
Reconnect the ignition suppressor box, then install the recoil,
using the 4 , 10mm socket held bolts and washers.
Remember to check for correct recoil rope positioning.
Install the fan protector, making sure that none of the wiring is
disconnected during installation.
Fan belt adjustment
Tools required
Fan fixation tool
Rotax spark plug wrench/ 21mm socket
Fan fixation tool
Rotax spark plug wrench/ 21mm socket
Fan belt adjustment
Remove the fan cover by bending the three tabs retaining it out
and gently prying out on the cover. Insert the fan fixation tool into the fan as shown .
Using the small end of the Rotax spark plug wrench or a 21mm socket/ratchet, turn the nut
on the fan shaft counter clockwise. Remove the nut, washer and fan. Be careful not to lose
the key located in the fan shaft. Behind the fan are a series of shims. These control the
fan belt adjustment. The removal of shims tightens the belt by shortening the distance
between the two pulley halves while the addition of shims loosens the belt by increasing
the distance.
Proper adjustment is attained when belt deflection is
approximately 1/3 of an inch, at the belt center, when 10 lbs of pressure is applied.When
reinstalling place shims that have been removed as per update fig 1 so that they may be
reused when a new belt is installed. Belt adjustment should be done within 25 hours of
installation and checked on a regular basis.
Disassembly - Rewind starter
Removal from engine
Tools required
10 mm deep reach socket
Ratchet
Snap ring pliers
Knife
Matches
Shop supplies
Low temperature grease
Molykote G-N paste Part#H4372
Low temperature grease
Molykote G-N paste Part#H4372
It may be necessary to remove the recoil handle on some engines
to allow removal from aircraft. To do this tie a slip knot in the recoil rope immediately
in front of the recoil. Undo or cut the recoil rope at the handle. Disconnect the ignition
suppressor box wires, (black and red) from the ignition coil wire plugs (blue/red
-blue/black). Remove the four 10 mm socket head bolts and lock washers which hold the
rewind starter to the engine. The recoil will come free.
Disassembly-Rope removal
Remove snap ring (1), lock spring,(2) circlip (3) and pawl (4)
from recoil starter.
Remove the rope sheave from the recoil. Place a blade screw
driver into the hole where the recoil rope exits the sheave.
Reassembly - Rewind starter
When the screwdriver comes up against the key clamp
push until the key moves releasing the rope.
Inspection
Inspect recoil spring, rope and mechanism for damaged
worn or broken parts. Replace as necessary.
Maintenance
To ensure long trouble free operation of the recoil occasional
maintenance is suggested. This maintenance involves light lubrication of the recoil rewind
starter spring with low temperature grease. Plus lubrication of the pawl lock spring with
Molykote G-N paste.
Reassembly
Tie a knot in recoil handle end of the recoil rope. Install
sheave into starter housing, ensuring notch in sheave engages in the spring hook. Rotate
sheave assembly counter clockwise until spring is fully compressed. While holding spring
under tension, release one turn, and align hole in sheave with recoil housing rope inlet.
Install the other end of the rope through housing and into sheave until it passes through
window in sheave. Install key clamp into window with teeth pointing so that they bite into
rope when a pulling pressure is applied. Lock key clamp. Release tension and recoil rope
will be rewound into housing. Reinstall pawl, pawl lock and circlip. Prior to installation
of locking spring lubricate with Molykote G-N paste, install spring and install lock ring.
If convenient reinstall recoil handle. Pull rope out. Tie slip
knot at recoil, burn end of rope. Install rope into handle and tie knot in rope. Release
slip knot, install recoil on engine in reverse order or removal.
Disassembly - Carburetor
Tools required
Flat blade screw driver (supplied in Rotax tool kit)
Phillips screw driver
Small adjustable wrench
Flat blade screw driver (supplied in Rotax tool kit)
Phillips screw driver
Small adjustable wrench
Shop supplies
General purpose cleaner
General purpose cleaner
Carburetor removal
To disconnect carburetor from engine loosen clamps holding
carburetor to rubber flange intake boot.Gently pull and the carburetor will separate from
the boot. To remove the top loosen the two retaining screws and the top of the carb will
come off (1).
To remove throttle cable, compress the carburetor piston spring (3), push
the white plastic spring cup (4) out of the carburetor piston (7) move the throttle cable
side ways in the carburetor piston. This allows it to release through the larger hole in
the bottom of the piston. Remove the jet needle (6) and retaining clip (5). Be careful not
to lose the rubber sealing ring (2) located in the carburetor cover plate
With the top removed place the carburetor on the bench upside
down. Slide the bowl spring clip side ways and the carb bowl will come free. (It may be
necessary to gently tap the bowl to break it free from the bowl gasket). Carefully remove
the gasket.
Disassembly - Carburetor
In the center of the carburetor covering the main jet will be a
seeve sleeve (8) (this looks like a little filter) Remove it (its purpose is to stop foam
from entering the main jet).
Looking at the top of the main jet you will see a number. This
indicates the size of the jet. For jets specifications refer to section P - 01. Remove the
main jet (9) . Remove the mixing tube and (10) this will allow removal of the needle jet
(11).
Located beside the main jet is an orifice containing the idler
jet (12). Using a small screw driver (supplied in Rotax tool kit), remove the idler jet.
Next remove the float pin (15) This will allow removal of the
float bracket (16) or float depending on which type your engine is using.
Under the float bracket is the float needle (14)and float needle
clip (13)Remove them. Two screws, one large and one small, are located on the side of the
carburetor. The larger screw with the spring under it is the idle (18) adjustment screw .
The smaller with the rubber ring under it is the air regulating screw(17).
Cleaning
Using a general purpose cleaning solvent clean all the parts.
Check the main jet and idler jet orifices to ensure that they are not plugged.Using
compressed air blow through the vent holes, main jet and idler jet.
Reassembly
Place the carb body on the bench inverted. Replace the needle jet
mixing tube and thread the main jet into the mixing tube.
Install the needle jet needle clip,and float bracket or float. If
properly adjusted, the float bracket arms should be level when the carburetor is sitting
inverted on the bench. Now turn the carburetor right side up and check to make sure that
the needle valve is not sticking. Invert the carb once more.
Install the idler jet.Install
the float chamber gasket and sieve sleeve. Install the floats (depending on carb style).
Install bowl gasket. Install float bowl and lock into place with the spring clip. Turning
carburetor over install the spring and idle adjustment screw. Install the O ring and air
regulating screw.
Engine idle speed for the 377/447/503 engines is 2,000 rpm under
full load conditions. The proper air screw adjustment is 1/2 turn except with dual intake
silencer when it is 1 turn. Install the throttle cable through the rubber grommet and
replace throttle cover plate.
Make sure that the rubber O ring is in place under the cover
plate. Install the carburetor piston spring. Install the white plastic spring cup over the
end of the carburetor piston spring using the cup compress the spring and making sure the
throttle cable protrudes through the correct hole in the spring cup. Install jet needle
and holding plate into the carburetor piston. Place the throttle cable end into the piston
and down through the hole in the side.
Once through, slide the throttle cable over and up
to lock it into position. Now allow the plastic spring cup to slide down over top of the
spring clip. Install the unit into the throttle body making sure that the piston guide
hole and carb body guide line up. Tighten up the two cover plate retaining screws.
Slip the
carburetor body into the rubber socket and make sure the arrow is pointing the direction
of fuel flow and tighten the retaining clamp.
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