Inspection Of Spark Plugs - Rotax MML-912 Maintenance Manual

14.2.2) Inspection of spark plugs

Check heat range and adjust electrode gap correspondingly.
Heat range
Inspect all spark plugs for mechanical damage.
Visual check
Electrode gap
0,6 - 0,7 mm (0.023 - 0.027 in)
NOTES:
Spark plug face reveals the following about the operating condition of the
Spark plug face
engine:
light coloured to brown
velvet black
oily, glossy coating
white with formation of
melt beads
Effectivity: 912 Series
Edition 2 / Rev. 0
BRP-Powertrain
MAINTENANCE MANUAL
New
Inspect the electrode gap also on use of new spark plugs.
The distance can changed by improper handling.
Spark plug face
plug and calibration of the engine are correct
Indicates the following:
-
-
-
Indicates the following:
-
-
-
-
Indicates the following:
-
-
Electrode gap
0,9 mm (0.035 in)
Information
mixture too rich
insufficient air intake (clogged air filter)
engine operating temperature too low
damaged valve stem seal
misfiring
too much oil in combustion chamber
worn cylinder and piston rings
mixture too lean
leaking valves
Wear limit
12-20-00
page 64
October 01/2009