Ski-Doo Formula S 1998, Shop Manual

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Section 03 TROUBLESHOOTING
Subsection 02 (ENGINE)
03-02-3
4. Melted and/or perforated piston dome; melted section at ring end gap.
a. When piston reaches TDC, mixture is ignited by heated areas in combustion chamber.
This situation is due to an incomplete combustion of a poor quality oil.
Clean residue accumulation in combustion chamber and replace piston(s). Use
Bombardier Rotax oil.
b. Spark plug heat range is too high.
Install recommended spark plug(s) (refer to TECHNICAL DATA 10).
c. Ignition timing is too advanced.
Adjust according to specifications (refer to TECHNICAL DATA 10).
d. Inadequate fuel quality.
Use appropriate fuel.
e. Carburetion is too lean.
Adjust according to specifications (refer to TECHNICAL DATA 10).
5. Seized piston all around the circumference (dry surface).
a. Lack of oil, damaged oil line or defective injection pump.
Replace defective part(s).
6. Grooves on intake side of piston only.
a. Oil film eliminated by water (snow infiltration in engine).
Replace piston(s) and check if intake system leaks.
7. Piston color is dark due to seizure on intake and exhaust sides.
a. Broken or loose fan belt.
Replace fan belt or adjust its tension (refer to TECHNICAL DATA 10).
b. Cooling system leaks and lowers coolant level.
Tighten clamps or replace defective parts. Add antifreeze in cooling system until
appropriate level is reached.
c. Accumulation of foreign particles in needle and/or main jet area.
Clean carburetor(s).
8. Cracked or broken piston(s).
a. Cracked or broken piston(s) due to excessive piston/cylinder clearance or engine
overreving.
Replace piston(s). Check piston/cylinder clearance (refer to TECHNICAL DATA 10).
Adjust drive pulley according to specifications (refer to TECHNICAL DATA 10)
and/or clean pulley sheaves if they are contaminated with greasy particles.
SYMPTOM PISTON RING AND CYLINDER SURFACES ARE GROOVED.
CONDITION NORMAL USE.
Test/Inspection 1. Check oil quality.
a. Poor oil quality.
Use Bombardier Rotax oil.
2. Check injection pump and its hoses.
a. Inadequate injection pump adjustment and/or defective hoses.
Adjust pump according to specifications (refer to ENGINE 04) and/or replace hoses.