Husqvarna SM 50 / 2011, Workshop Manual

Page: 90 / 150

F.24
Ed. 01-09-2010
ENGINE
FAULT CAUSE REMEDY
Too low engine power Fuel supply partially inter-
rupted or pipes not correctly
positioned
Loss of compression due to
a loose spark plug
Exhaust pipe bent or faulty
Reed plates without tension
or reed crankcase sealing
surfaces or reed plates da-
maged
Wear signs
Blow through fuel duct, and clean carburettor.
Tighten spark plug.
Check exhaust pipe for any damage.
Change reed plates or reed crankcase.
Overhaul engine
Engine rpm do not increa-
se and engine runs at four
strokes
Carburettor overflows due to
a too high level adjustment,
floater needle seat is dirty
or worn
Loose carburettor jets
Clean carburettor, change floater needle, if necessary, and adjust le -
vel
Tighten carburettor jets
Engine misses at high rpm Spark plug has a poor qua-
lity or a wrong heat rating
Loose or oxidised ignition
system connectors
Use one of the spark plugs listed in the "Technical Specifications"
Check connectors, and seal them with silicone
Engine misfires No fuel
The installed spark plug
has a wrong heat rating
(self-ignition)
The engine intake is incor-
rect.
Clean fuel ducts, check tank breather hose, and clean fuel
Use one of the spark plugs listed in the "Technical Specifications"
Check cylinder and carburettor tightening, check that intake flange
does not show any crack
The engine overheats No fluid inside cooling sy -
stem
Very dirty radiator fins.
Foam inside cooling sy-
stem
Bent water pipe
Wrong advance due to loo-
se stator
Compression adjustment
too high
Top up coolant. Check cooling system sealing.
Clean radiator fins with a soft jet of water.
Change coolant, use branded anti-freeze and antirust additive.
Fix water pipe.
Tighten screws, and secure them with Loctite 243
Correctly adjust compression.
White smoke release (va-
pour inside exhaust gases)
Faulty cylinder head or ga-
sket (and O-rings)
Check cylinder head, and change cylinder head gasket (with O-rings),
if necessary