Ski-Doo FORMULA S 1997, Shop Manual

Page: 664 / 926

Section 02 TROUBLESHOOTING
Sub-Section 02 (ENGINE)
02-02-3
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 09).
c.Ignition timing is too advanced.
Adjust according to specifications (refer to TECHNICAL DATA 09).
d.Inadequate fuel quality.
Use appropriate fuel.
e.Carburetion is too lean.
Adjust according to specifications (refer to TECHNICAL DATA 09).
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 09).
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 09).
Adjust drive pulley according to specifications
(refer to TECHNICAL DATA 09) and/or clean pulley sheaves if they are
contaminated with greasy particles.