18) Renewal Of Spark Plugs; 19) Checking Of Spark Plug Connector For Tight Fit - Rotax 914 F Maintenance Manual

12.3.18) Renewal of spark plugs

Renew spark plugs according to Maintenance check list. Use only original
spark plugs of 12 mm ND X27EPR-U9.
Renew always both plugs of a cylinder and do not interchange between
cylinders.
Remove spark plugs and put them aside coordinated to cylinder and position.
Plug face appearance reveals the following about operating condition of
engine:

12.3.19) Checking of spark plug connector for tight fit

Check spark plug connector for tight fit on spark plug every 200 hours of
operation. Min. pull-off force to be 30 N (7 lbf.). Renew loosely fitting spark
plug connectors.
Modification no.
- 0 -
ATTENTION: Tighten spark plugs to 20 Nm (180 in.lb) on the cold engine
only.
light coloured to brown
plug and calibration 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:
— misfiring
— too much oil in combustion chamber
— worn cylinder and piston rings
whitish with melt droplets
Indicates the following:
— mixture too lean
— leaking valves
— air box temperature too high
— fuel control incorrect adjusted or defective
— faulty control valve
— poor fuel quality
Reference Main Date
914 F 1997 02 01
Page
107