Rotax 915 i A SERIES Maintenance Manual page 118

Step
Figure 7.3: Valve seat debris removal
If the pressure drop value is still out of range, heavy maintenance must be carried out by
authorized persons (iRMT, Level Heavy Maintenance).
Following troubleshooting reasons might be applicable but are not exclusively limited to:
• Excessive cylinder wall and/or piston ring wear
• Broken piston rings
• Burned valves
• Piston damage
12–20–00
Page 10
December 01 2017
BRP-Rotax
MAINTENANCE MANUAL
Procedure
3 Place a plastic drift (2) on the rocker arm (1) (directly over the inlet valve
stem). See Fig.
4 Use a hammer to give a slight blow onto the fibre drift to dislodge any for-
eign material between the intake valve face and seat. During this step the
cylinder must be pressurized by using the setup used for the differential
pressure test procedure to allow carrying away debris from the valve seat.
5
Turn the crankshaft into a position, so that the exhaust valve is closed and
perform step 3 and 4 for the exhaust valve.
6 Install valve cover according to the latest Maintenance Manual Heavy.
7 Measure the pressure drop again as described in the differential pressure
test procedure.
1 Rocker arm
Valve seat debris removal.
2 Plastic drift
Effectivity: 915 i A Series
Edition 0/Rev. 0