Rotax 914 series, Maintenance Manual

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MAINTENANCE MANUAL
BRP-Powertrain
Effectivity: 914 Series
Edition 2 / Rev. 0
12-20-00
page 70
January 01/2010
16.2.2) Inspection of spark plugs
Heat range
Check heat range and adjust electrode gap correspondingly.
Visual check
Inspect all spark plugs for mechanical damage.
Electrode gap
NOTES: Inspect the electrode gap also on use of new spark plugs.
The gap could have been changed by improper handling.
Spark plug face
Spark plug face reveals the following about the operating condition of the
engine:
Electrode gap
New Wear limit
0.6 - 0.7 mm (0.023 - 0.027 in) 0.9 mm (0.035 in)
Spark plug face Information
light coloured to brown plug and calibration of the engine are correct
velvet black Indicates the following:
- mixture too rich
- insufficient air intake (clogged air filter)
- engine operating temperature too low
oily, glossy coating Indicates the following:
- damaged valve stem seal
- misfiring
- too much oil in combustion chamber
- worn cylinder and piston rings
white with formation of
melt beads Indicates the following:
- mixture too lean
- leaking valves