BRP-Rotax
MAINTENANCE MANUAL
Special tools To measure the compression pressure the following special tools and equipment are
necessary.
Part number Description
n.a.
Compressed air approx. 6 bar (600 kPa).
n.a
2 pressure gauges.
n.a
Orifice jet*, of 1 mm (0.04 in) inner diameter and 3 mm (0.12 in)
length. * or equivalent e.g. orifice diameter 0.040 in., long 0.0250
in., 60° degree approach angle according to AC43.13, latest
issue.
n.a
Adapter to spark plug thread.
n.a
Connect line.
Instruction Testing is carried out using the differential pressure test procedure.
Step
Procedure
1
Operate the engine until the temperatures have stabilized for a period of 5
min (engine oil temperature between 50 to 70 °C (122 - 160 °F).
2 Starting with cylinder head 1 move piston to TDC position.
3
Remove the upper spark plugs. Prevent dirt or other foreigner particles from
penetrating the engine (A).
4
Screw adaptor (1) into the spark plug thread and connect up the two pres-
sure gauges (2) with the orifice jet (3) between them (B).
5
Now put constant pressure, between 5.5-6 bar (550-600 kPa) on the line
and take readings at pressure gauge (C)..
6 Repeat this proceeding at all 4 cylinder heads.
Value The maximum permissible pressure drop is 45 %.
Procedure if maximum permissible pressure drop is out of range:
Recheck the readings after operating the engine in a test run for at least 3 minutes. This
will allow the piston rings to be wetted with oil. Measure the pressure drop again as de-
scribed in the differential pressure test procedure. If the pressure loss is still out of range,
valve seat debris removal procedure must be carried out.
Valve seat debris removal procedure
Step
Procedure
1 Remove the valve cover according to the latest Maintenance Manual
Heavy.
2
Turn the crankshaft into the position, so that the intake valve is closed.
Effectivity: 915 i A Series
Edition 0/Rev. 0
12–20–00
Page 9
December 01 2017
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