Rotax 277, Rotax  reduction drive removal.

Rotax Reduction Drive-Removal .
Tools Required.
13 mm socket
() mm socket
ratchet
() mm allen wrench
propane torch
hammer
Oil drain pan
Rotax reduction drive gear puller
Johnson bar
12 inches rope
Spark plug wrench 

For engine disassembly, or reduction drive repair it is necessary to remove the reduction drive from the engine assembly. First drain the oil from the gear drive assembly, using a () mm wrench to remove the drain plug from the bottom of the gear drive. With a ratchet and socket/wrench and loosen the six, 13 mm nuts, retaining the drive to the adapter plate. With all the nuts loose remove the top 4 in a gear down assembly, or the bottom 4, in a gear up assembly.

Grasp the drive by the output shaft, and pull outwards on the drive. On older model drives it may be necessary to turn the engine over while pulling out to allow the gear to clear the gear oil slinger
This slingers no longer used and should be discarded.
With the drive removed it is next necessary to remove the adapter plate. To allow access to the 4 allen head screws securing the adapter plate to the gear drive, it maybe necessary to remove the 4 studs used to hold the gear drive to the adapter plate. To do this screw one of the 13 mm nuts removed from the studs onto the stud, until it is near the bottom of the threads. Now install another nut onto the stud until it locks against the first nut. Now using 2, 13 mm wrenches tighten the nuts against each other. Then come in and using a 13 mm wrench remove the stud, by turning counter clockwise on the first nut. Repeat for the remaining studs as necessary.

With the studs removed, use a hammer and sharply wrap each of the allen head retaining screws. This will help shock them loose from the Blue Loctite used to help retain them. Before attempting to remove the allen screws it is suggested that you use a propane torch or B tank to heat the crankcase, in the area of the threads holding the bolts.

With the bolts shocked, the crankcase thread areas heated, use an allen wrench to remove the four retaining screws. If you strip the heads of the screws, use a pair of VICE GRIP style pliers to grab the outside of the screws, to aid in removal. 

Tools Required Tools Required
.() socket
ratchet
Rotax gear puller
12" piece of rope spark plug wrench

Procedure

Using a spark plug wrench remove the spark plug from the PTO side cylinder. Turn the engine over clockwise until it is past TDC and the piston is positioned about 1 inch down in the cylinder. Take your 12 inches of rope and feed it through the spark plug hole until 8 inches or so are located in the combustion chamber.

Turn the engine over counter clockwise, until it locks up. Place your () mm socket onto the bolts retaining the gear to the crankshaft. Using a Johnson bar turn the socket counter clockwise until the bolt comes free. Remove the bolt, washer, and impeller, if so equipped.

With the bolt removed, remove the rope from spark plug hole. Turn the engine over until the PTO piston is at TDC. Rotate the crankshaft counter clockwise until the piston is approximately 1 inch down in the cylinder. Again install your rope. Bring the piston up until the engine locks up.

Install your Rotax gear puller into the threaded section of the gear being sure to thread the outer puller half of the puller all the way in. Then by hand turn

Install the puller bolt in until it butts against the crankshaft end. Install a () mm socket onto the end of the puller bolt, then using a Johnson bar turn the bolt in a clockwise direction until the gear comes free of the crankshaft. 

1. Clean and degrease the crankshaft end and mounting holes on the crankcase before starting.
2. Using the Rotax fixation tool supplied in the Rotax tool kit lock the engine up by installing the pin into the impulse hole, used to run the fuel pump. With the pin in place rotate the engine, until it locks.
3. Install drive gear onto crankshaft end, with the lockwasher under the head of the bolt, and the flat washer under the lockwasher. Torque to 45 FOOT lbs.
4. Install the rubber O ring (#3) into the back half of the gearbox adapter plate, if necessary use dielectric grease to hold ring in place.
5. Position back half of gearbox (#1) onto crankcase. Apply loctite #242 to threads of bolts (#4) install 4 allen bolts bolts and torque 30 FOOT lbs.
6. Install the rubber O ring (#3) into the front half of the gearbox adapter plate, if necessary use dielectric grease to hold ring in place.
7. Install back half of gear box housing.
8.Install gasket - make sure gasket is not damaged.
9. Install front half of gear box housing and secure with bolts/nuts and lockwashers. Use loctite 242 on threads and torque to 195 INCH lbs.
10. Fill gear box with 90 weight oil until oil runs out the lower of the two side plugs.
11. Tighten then safety wire top and bottom plugs.
12. Tighten then safety wire vent cap and drain plug.