AquaCraft 18 Marine Engine - Manual (Page 2)

The High-Speed Needle The
“high-speed”
needle is stic
king up from the side of the carb
.
It is located in the br
ass housing, just abo
v
e
the fuel inlet.
It
controls the fuel to air mixture of the carb
.The needle is pre-set
fo
r break-in from the f
a
ctor
y at 2 tur
ns out from the fully closed
position of the carb
.
Once the engine is brok
en-in, the high-
speed needle w
ould typically r
un from 1-1/4 to 1-3/8 tur
ns out
from closed (2 tur
ns to star
t break-in), depending on the
w
eather
, humidity and altitude abo
v
e
sea le
v
el.
T
o
r
ichen tur
n
the needle countercloc
kwise
, to lean tur
n
the needle cloc
kwise
.
The Lo
w-Speed Needle
The
“lo
w-speed”
needle is the scre
w in the carb body
, in the end
of the throttle ar
m.
It controls the fuel to air mixture at lo
w throttle
settings
.
There is a simple w
a
y of adjusting the lo
w-speed
needle correctly called the
“pinch test.
”
With the engine at idle
,
pinch the fuel line and listen to ho
w the engine speeds up or
slo
ws do
wn.
If the engine increases its speed f
o
r about 3 or 4
seconds and then loses speed, the needle is set correctly
.
If the
engine loses RPM quic
kly
, it is set too lean and the lo
w-speed
needle needs to be opened (countercloc
kwise) to r
ichen the
mixture
.
Pinch again to chec
k the mixture
.
If the engine tak
es
longer than 5 seconds to slo
w do
wn, lean (cloc
kwise) the lo
w-
speed needle and then pinch again to chec
k the mixture
.
The
Thr
ottle Stop Scre
w
T
u
rn
the throttle stop scre
w out 1 full tur
n
bef
ore installing the
engine in y
our boat.
The carb
uretor barrel should fully close with
the throttle ar
m fully bac
k.
Note:
This engine was designed to racing tolerances and
ma
y take long
er than 5 tanks to full
y break-in.
T
o
insure long lif
e and good perf
o
rmance from y
our AquaCr
aft
.18 engine
, y
ou
MUST
break-in the engine
.
The break-in per
iod
is cr
itical f
or long lif
e of the inter
nal par
ts of the engine
.
This
should be done o
v
er the first 5 or 6 tanks of fuel.
Some
Things
T
o
Remember During Break-In:
1.
Use the same fuel that y
ou will use f
or nor
mal r
unning.
2.
Resist the urge to acceler
ate and deceler
ate the boat quic
kly
.
3.
Break-in puts stress on the glo
w plug and y
ou can b
u
rn
it out
dur
ing break-in.
Mak
e sure y
ou ha
v
e
an e
xtr
a plug or tw
o
on hand.
Star
ting the Engine:
1.
Install a glo
w plug if one is not in y
our engine
.
This threads
into the top of the cylinder head.
2.
Fill the tank almost to the top
.
Lea
v
e
a little air at the top of
the tank.
3.
Pr
ime the engine b
y
co
v
e
ring the e
xhaust por
t and rotating
the flywheel on the engine
.W
atch the fuel go through the line
and when it gets to the carb
uretor
, tur
n the flywheel one more
full re
v
o
lution.
4.
Open the high speed needle v
alv
e 2 to 2-1/2 tur
ns out
(counter
c
loc
kwise)
from fully closed.
The high-speed
needle is stic
king up fr
om the carb
uretor inside the brass
housing.
All of the carb
uretor settings are adjusted with a flat
b
laded scre
wdr
iv
er
.
If y
ou ha
v
e
pre
v
iously r
un the boat, k
eep
the same needle v
alv
e setting that y
ou used on y
our last r
u
n.
5.
Star
t the engine b
y
pulling the recoil – use shor
t, quic
k
pulls
.
DO NO
T
pull the recoil star
ter’
s str
ing to the end.
6.
Once the engine is star
ted, open the high-speed needle
v
alv
e around 1/8 tur
n
at a time
, finding the setting where the
engine just barely r
uns
.
7.
Look at the smok
e that comes out the e
xhaust this is also a
good indicator of ho
w r
ich or lean the engine is r
unning.
If
there is a good amount of smok
e coming out of the e
xhaust,
then chances are good that y
ou are r
unning r
ich.
8.
Run the boat at a medium speed until the tank is almost out
of fuel.
Do not allo
w
the tank to r
un out of fuel.
This leans
out
the engine and can cause o
v
erheating (See
Ho
w T
o
Stop
Y
our
Engine
).
9.
Stop the engine and allo
w the engine to cool bef
ore the
second tank.
This nor
mally tak
es around 10 min
u
tes
.
If the engine does not star
t after se
v
e
ral pulls
, sometimes it is
helpful to star
t the engine at around half throttle
.
H
a
v
e a fr
iend
pull bac
k on the throttle some while y
ou star
t the engine
.
This
ma
y
be an indicator that the lo
w speed needle setting needs to
be adjusted.
When the engine star
ts
, immediately retur
n
the
throttle to idle
.
If this is not done the engine can o
v
er-re
v and
cause engine damage
.
If the engine is difficult to turn o
ver
with the recoil star
ter
,
especiall
y
if it is brand ne
w
,
loosen
the glo
w plug a half turn bef
o
re star
ting the engine
.
This
allo
ws some compression to escape
,
b
ut the engine will
BREAKING IN
THE ENGINE
CARB
URET
OR SETTINGS
still star
t.
Make sure y
ou tighten the glo
w plug after the
engine star
ts.
If the recoil star
ter is still difficult to pull, the
engine is flooded – there is too m
uch fuel inside the engine
.
Remo
v
e
the glo
w
plug and air cleaner
, then tur
n
the engine
upside do
wn and pull the recoil 5 or 6 times
.
This will clear the
engine of fuel, and y
ou will notice the recoil pulls easier
.Replace
the glo
w
plug and repeat the star
ting procedure
.
Fuels Use fuels that are specially f
o
rm
ulated f
or mar
ine engines
.
O’Donnell Boat Fuel is specially f
o
rm
ulated f
or engines lik
e the
AquaCr
aft .18.
Stopping Y
our
Engine
Y
ou will need to stop y
our engine as the boat approaches shore
.
Its best to dr
iv
e y
our boat par
allel to the shore and tur
n the boat
in AFTER the engine quits
.
Mak
e sure bef
ore y
ou r
un y
our boat
fo
r the first time
, that when y
ou push the throttle tr
igger full bac
k
that the engine shuts off
.
Complete the Break-In T
u
rn
in the needle v
alv
e (cloc
kwise) around 1/8 tur
n from the
pre
vious setting f
or each additional tank.
Y
ou should notice that
the engine will perf
or
m better dur
ing each r
un.
Stop the boat
per
iodically to chec
k f
or o
v
erheating.
If it is too hot, stop the
engine
.W
ait f
or it to cool, then open up the needle v
alv
e 1/4 tur
n
and restar
t.
After the 5th tank, y
ou should be near to the peak
perf
or
mance of the engine
.
Nine
W
a
ys
T
o
Ensure A Long Lif
e
Fr
om
Y
o
ur Engine:
1.
K
eep y
our engine clean.
Dir
t will act as insulation on an
engine
.
It will not be ab
le to shed heat as easily
.
2.
Do not o
v
er-lean y
our engine
.
3.
Do not r
un y
our engine with little or no load.
Don’t re
v the
engine up to full throttle with the boat out of the w
ater
.
4.
Do not o
v
erheat the engine
.
This goes along with k
eeping it
clean and not o
v
er-leaning the engine
.
5.
Mak
e sure y
ou use a fuel from a reputab
le man
u
facturer
,
such as O’Donnell Fuels
.
6.
A
v
oid using old fuels in the engine
.
A
lw
a
ys r
un all of the fuel
out of the engine
.
After r
unning f
o
r the da
y,
use an after-r
un
oil and w
o
rk
it into the engine b
y
tur
ning the flywheel or
pulling the engine recoil slo
wly
.
7.
Do not scr
atch the piston or cylinder slee
v
e
.
A
v
o
id jamming
something into the e
xhaust por
t when remo
ving or re-installing
the flywheel.
Use a special tool called a cr
ankshaft loc
king tool
(not included), which is installed in the glo
w plug hole
.
8.
Do not use silicone sealer on the engine joints
.
Silicone
sealer contains acetic acid, which is corrosiv
e if it gets inside
y
our engine
.
9.
T
emper
ature changes can cause condensation inside the
engine
.
Use an after-r
un oil to protect the inside of y
our
engine
.
S
tore y
our engine inside the house
, not in a gar
age
or shed where there will be temper
ature e
x
tremes
.
Glo
w Plug
The glo
w
plug is an item that will w
ear out and need
replacement from time to time
.
It is a good idea to remo
v
e
the
glo
w
plug bef
ore y
our first r
un, heat it and see ho
w w
ell it glo
ws
.
Y
ou should see a br
ight or
ange glo
w
from the filament.
If a coil
or tw
o will not glo
w or the plug will not glo
w at all, replace the
plug.
If the engine quits when y
ou remo
v
e the glo
w
star
ter
, the
plug might need to be changed, although this ma
y be because
y
ou are r
unning too r
ich and need to scre
w in y
our high-speed
needle some
.
Look at the glo
w plug when y
ou are r
unning the
engine
.
If y
ou see some b
u
b
b
les coming from around the plug,
replace the glo
w plug (copper) gask
et, or both the plug and
gask
et.
The only real w
a
y to test a glo
w plug is to replace it.
Mak
e sure y
ou ha
v
e
a spare plug or tw
o (Silv
er Spor
t Glo
w
Plug-DTXG3001) on hand when y
ou r
un the engine
.
Fuel Fuel can go bad.
The main ing
redient in model fuel is methanol,
which can absorb w
a
ter out of the air
, so k
eep y
our fuel jug
capped at all times
.
S
tore y
our fuel out of the sunlight and in a
cool place
.
Bad fuel is one of the most difficult prob
lems to
diagnose in engines
.
If y
ou ha
v
e
tr
ied e
v
er
ything y
ou can think
of to remedy an engine that is not r
unning correctly
, tr
y using
some fresh fuel. Maintenance Fuel line is susceptib
le to pinhole leaks
.Y
ou cannot see the hole
in the fuel line
, b
u
t if y
ou see air b
u
b
b
les in the line going to the
carb
uretor
, replace the fuel line
.
Another symptom of a leak in
the fuel line is a surging engine
.
The proper
ly tuned engine will
surge when the air b
u
b
b
les hit the carb
.
It is basically leaning out
the mixture
.
T
o
k
eep dir
t out of the engine
, w
e
recommend that y
ou use an
inline fuel filter (Clean-Flo
w Fuel Filter-DTXC2551) on the fuel
line r
unning from the fuel tank to the carb
uretor
.
Dir
t can get
caught in the needle seat and cause an inconsistent r
unning
engine
.
If y
ou suspect that some dir
t has lodged itself in the
carb
, remo
v
e
the needles and clean the carb with denatured
alcohol or fuel.
It can help to use compressed air to b
lo
w
out the
fuel passages as w
e
ll.
ENGINE MAINTENANCE