
04-4
SECTION 04 - PROPULSION SYSTEM
If everything is in good order but the watercraft
does not accelerate quickly when depressing the
throttle lever and a good top speed cannot be ob-
tained, the pump is probably ventilating; then, the
ride shoe must be removed and resealed to the
hull. Refer to appropriate model year
Shop Manual.
NOTE:
When resealing ride shoe ensure to elimi-
nate any possible flow restriction (excessive seal-
er build up). Use the silicone “Ultra Black HB” (P/N
293 800 028), which has the fastest curing time.
CAVITATION
Cavitation can be defined as a phenomenon
where the water inside the inlet or pump be-
comes incapable of keeping up with the flow.
Therefore a negative pressure within the system
occurs creating gas vapor and ultimately cavita-
tion. As these gas vapor bubbles implode, they
generate enough force to remove microscopic
particles of material within the pump assembly.
This usually can be seen in the form of discolored
areas or trails within the pump assembly (on the
stator vanes or impeller). These areas look as
though they have been sand-blasted.
A certain degree of cavitation is an accepted oc-
currence with a water jet propulsion system.
However, some changes within the pump can re-
duce cavitation, such as replacing a thick bladed
aluminum impeller with a thin bladed stainless
steel impeller; removing any scratches or dents in
the housing/impeller, or replacing wear ring if
worn.
Chamfer and/or radius leading edges of stator
vanes.
Using a straight file, break the square edge on
both sides of stator vane to about 1.3 mm (.050 in)
wide, then use about a 2 foot strip of 1 inch wide
sandpaper (100 grit min.) and drape sandpaper
over stator vane area already filed by placing one
end of sandpaper in one tunnel and the other end
in the tunnel directly adjacent to the first and fin-
ish dressing the leading edge. This procedure
should be done to both the leading and trailing
edges of stator vanes.
1. Reworked vanes
2. Tunnel
3. Break these edges slightly
4. Be careful not to make a sharp or square corner in these areas
It is important to realize that water conditions and
repeated accelerations will increase cavitation.
Verify if engine speed is high but watercraft
moves slowly due to reduced jet thrust. Check jet
pump components for damage.
Refer to appropriate model year
Shop Manual.
IMPELLER
Two types of impellers can be installed in the jet
pump, the regular fixed pitch and the progressive
pitch impellers. The meaning of the term “pitch”
is the angle between the edge of the blade and
the surface on which the impeller is sitting on, or
the angle at which impeller moves the water.
1. Angle
2. Flat surface
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Содержание Bombardier
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