MODUSA
& Co
Engine set up
General Notes
This is not an all
Stalker-Modusa engine specific set of guidance notes, it is general in
nature and covers all or most engines. There are some aspects that
are specific to Stalker-Modusa engines, for example:- engine dismantling
procedure, long reach plugs, our recommendations on fuel. An example of a
guidance note that applies to all engines is the use of compression
compensating head shims/gaskets when increasing the nitro level in the
fuel.
ENGINE
Prime:
- Try with half as much as normal. These engines need very little
in the way of priming and are easy to start.
Running
In – 1.5 to 2 hours on the bench. Use same fuel as you would for
flying.
It is not recommended that you use your flying prop
(5.5”-6”) pitch for bench running the engine.
Use a 4.5” or 4” pitch prop for bench
running. There
is no requirement for the use of high oil content fuel for running in the
engine. If engine run is
erratic and usual checks have been carried out, ie spray bar correctly
aligned in Venturi, water in fuel (use fresh fuel - methanol absorbs
moisture), change plug, center line of fuel tank in line with spray bar
etc then check for engine run time for given amount of fuel.
If engine run time continues to lengthen for the same amount of
fuel, then the engine needs more running in.
Engine is ready when engine run time stabilizes. Can also be
checked using a Tach-meter – engine should maintain revs at varying
needle settings or pinch the fuel line and check revs.
Venturi
- a good starting point is a venturi size of around 7.6mm. Using too much
fuel or producing too much power - change to a smaller size 7.4mm or
smaller.
Stalker
61 2/2 engine – not to be confused with over revving modified Schnuerle
ported engines that need low pitched props. . If incorrectly propped, the
61 2/2 will run 4/2. Be
patient, try different props until you find the right one that will work
with your model and that gets the engine to run 2/2. The 61 2/2 engine
runs at a lower rpm (7600rpm) than the other Stalker 4/2 engines (8200+).
The other exception to the rule is the 40RE that runs around 9600 rpm
(10-15% nitro) for an excellent 4/2 break run.
Fuel
- 17% to 22% synthetic oil
(Klotz is recommended) , no castor
oil for Stalker ABC piston/liner.
WE DO NOT RECOMMEND THE USE CASTOR OIL IN THE
FUEL.
Nitro 5 -15% depending on wind conditions etc., more Nitro
less fuel economy. For 0% nitro fuel, remove one or two of the fitted head
gaskets, for 8-15% nitro add one or two extra gaskets. Increasing
the nitro content of the fuel also increases the compression and you MUST
allow for this by adding the extra head gaskets. If
you do not add the extra head gaskets you will cause damage to the small
end of the con-rod, possible snap the gudgeon pin and or damage the
piston.
click
here for information on Model-Technics fuel's formulated for Irvine
engines that suit Stalker-Modusa engines.
for information on Klotz oils go to:
www.klotzlube.com/
If
you decide to use a castor-based fuel, do not subsequently switch to
all synthetic oil based fuel. If you are a must use Castor
person, then keep it to a minimum, for example
12% Klotz and 5% Castor or 10% Klotz and 7%
Castor - DO USE A DE-GUMMED CASTOR OIL
Castor
leaves residue on the underside of the head and on the top of the piston,
and gums up the bearings. If you do not remove the residue from time to
time, the engine will eventually fail to run correctly. An annual de-coke
is recommended.
The
best way to get the right fuel mix is to buy a gallon of methanol, ¼
gallon of nitro and ½ gallon Klotz and a small plastic measure, and mix
what you need for a weekend’s flying.
All you need is to set your fuel mix ratio – say 20 measures oil
to 5 measures of nitro and 75 measures of methanol gives you a 5% nitro,
20% oil fuel mix. It is as simple as that. You know what’s in the fuel,
you can vary the mix, its fresh and in the long run it’s cheaper too.
With
the recommended oil content of 17% - 22%, the piston liner is warranted
for four years against premature wear or damage through overheating.
Plug
- Ideally a 5mm plug - what ever that takes your fancy.
Unfortunately the excellent Russian plugs are no longer available.
The Hobby Shack plug works well as does the Enya No3.
Try two or three types of plug until you find one that works well
for you. IMPORTANT.
Do not force fit a plug. If necessary try running a 1/4-32 tap.
Props:
Try a Stalker CF prop - 12 x 6 or the new 13 x 5.5 on the 61-size engine.
You need to find the prop that works best with your
engine/model/plug/fuel set up. The 12 x 6 however is a pretty safe bet on
the 61 and will give you an excellent reference point.. The new 11.5 x 5.5
is worth trying on the much lighter and smaller 46/51RE engines.
Although we refer to our props in imperial sizes ( inches) the props are
in fact metric sized. Yes, Europe and most of the world uses the metric
form of measurement. Confused? This is why we give the nearest universally
recognized prop sizes in inches. Funny old world we live in.
The
11 x 6 two blade and the 10 x 6 three blade Stalker CF props set the
standard for 40 size engines as is near mandatory for use with the Stalker
40 size engines. You will be surprised as to how much more power these
props will produce. Other than that we think these are the best-made CF
props on the market.
Side
exhaust versions of the 55 and 61 are supplied with a muffler that
features a rotatable end section to allow installation sidewinder, upright
or inverted -
directs the exhaust away from the model. Add a smear of thread-lock to the
end bolt to prevent it vibrating loose.
STM40
and STM46 SE engines have the same external crankcase dimensions,
similarly the St46RE and St51 RE engines.
It must be said that each of the engine crankcases are made from
different moulds, hence the casting on the side of the engine with the
engine type – STM40, STM46 St46RE, St51RE. The STM40 is very slightly
lighter than the STM46 and the St46RE is lighter (5 grms) than the St51RE.
This is because the larger capacity engines have larger brass
piston liners, and brass is heavier than the aluminum of the crankcase.
All
Stalker-Modusa engines are covered by a money back guarantee, four-year
warranty on the piston and liner when using the recommended low oil
content fuel and a life time warranty against defective components.
HEAT DISPERSION
Make
sure there is plenty of air circulation around the engine head. Yes, the
crankcase needs cooling but more importantly the head.
A poor cowl design will cause the engine to overheat and run
erratically. Most of the heat is dispersed through the engine HEAD. We see
far too many cowl designs that restrict air flow over the head.
Looks good but baaad for the engine
Model/Engine/Prop/Plug/Fuel/Venturi/Compression
Optimization
You
need a Tach meter, Pitch gauge and a note pad plus of course a number of
props of known pitch and quality, two or three different makes of long
reach plug, head gaskets and two sizes of venturi.
Start
with the engine as supplied making notes of the model/engine performance
with each change of prop. Then change the plug and check the
performance with differing props. Do the same with differing oil/methanol mixes of
fuel. Keep the nitro level the same. This will give you a very good idea of how the model/engine behaves
with each change of plug, prop and fuel mix. You should only proceed to
make changes to compression/nitro and venturi size once you have the basic data
on how the model behaves with the changes in the three fundamental
components. Do not make assumptions, check it out and make a note and
compare results. These notes will serve you well in the future.
 |
The effect of castor after a few season
use |
 |
ALWAYS
USE A T
BAR HEX TOOL TO UNDO HEAD BOLTS. Socket
head bolts have a tendency to loose it’s shape and there is nothing
worse than to find the hex tool will not do its job and the only remaining
alternative is to cut the bolt. Consider replacing the bolts after you have taken out and refitted the
bolts two or three times. The 3mm bolts used
on Stalker engines are of UK origin and of the very best quality
Engine
Mounts/Fixing.
It is
still largely the practice to rely on the age-old method of simply bolting
the engine to the two wood bearers using 4-40 bolts and blind nuts.
This is simply not good enough!
We
would recommend (essential?) the following.
note fixing for RE
muffler
Fit
1)
Carbon fiber tissue reinforced half fuselage lite ply former at the rear of the
engine.
2)
Carbon fiber tissue reinforced thin lite ply sheet across the bearers from
the rear of the engine to the fuselage former. Remember that the
sheet plus the steel plates describe in 4) below will change the thrust
line, so make allowance when fitting the engine bearers.
3)
Optional second half fuselage former half way between the rear of the
engine and the fuselage former.
4)
Thin metal plate on top of the engine bearer with an steel plate on the
under side. Tap the alu plate for either 3mm or 4-40 bolts.
Use two bolts to hold
the plates on top and below the engine bearer. Use two bolts on each side
to install the engine the engine. The two plates will ensure that there is
no crushing of the bearers over time and will make it easy to change to
engines of different bolt fixing positions by simply substituting
different plates.
5)
Use Carbon Fibre tissue in the engine bay area and over the engine bearers
Remember
that an engine in a four-stroke mode is misfiring. An engine running 4/2 must vibrate more than one running in a
2/2 mode. Give the engine every opportunity to work at its best by
providing as rigid a mounting that you can provide.
REAR EXHAUST
MUFFLER: Ideally fix the
rear end of the muffler so that there is little or no movement.
The tube on the rear end of the muffler is designed to fit over a rubber
covered section of dowel. The dowel is fixed to the fuselage former (see
photo above, the red rubber is just visible).
If the muffler moves, there will be some exhaust leakage at the
stack. This can be minimized
by adding a V ring on the muffler neck pushed up against the stack or use
a short length of silicone tubing over the exhaust stack and the neck of
the muffler.
 note
vent for air flow for RE muffler
Exhaust
modifications -aluminium tube - wish to extend the exhaust outlet point, remove baffles or
shorten the muffler: -
Gently heat the cast sections
of the muffler and it will come undone.
Beware; the adhesive gives off a nasty odour. You can now add or
remove baffles, cut the tube to the desired length or drill out the end
section and add a length of aluminium tube to extend the outlet and
terminate with something like a Dynaflite exhaust deflector.
Composite
tube muffler- to shorten length- as there is a maximum temperature
that the tube can withstand, it is necessary to cut the tube to the
desired length. Then heat the aluminium section that has the tube section
to be disposed of. If you heat the aluminium sections there is every
possibility that you will deform the composite tube.
Glue
back with something like JB Weld, a USA product (available in the UK from
Halfords). Alternatively
re-cycle those excellent miniature screws from kiddie toys and use to hold
the cast sections to the aluminum tube
.
If you wish to add tank
pressure, the best position to tap in a nipple is usually the shoulder on
the neck of the muffler.
If
you find using the O rings inconvenient, then apply PTFE tape (from a
plumbers shop and cost little) to the muffler to get a good fit. Obtain a
short length of Silicone tubing – thin walled, from your local hobby
shop and use it over the muffler neck and exhaust stub and secure with a
nylon tie.
FUEL TANK
Never
build in the tank. It must always be accessible.
ENGINE
DISASSEMBLY
ENGINE
DISASSEMBLY
- IF UNSURE, NEVER EXPERIMENT, GET THE HELP OF AN EXPERIENCED
ENGINE MAN TO DO IT FOR YOU.
I MEAN
SOMEONE WHO KNOWS WHAT THEY ARE DOING AND NOT SOMEONE WHO CLAIMS TO KNOW
ABOUT ENGINES!
Plain
bearing engine.
Loosen head bolt one-eighth
turn, then loosen bolt on opposite side and move along in the same manner.
Loosen then quarter turn in the same manner until bolts are loose.
If bolt is tight, do not try and force with standard L hex key,
use a T handle hex key.
Remove head. If bolts resist your efforts with aT handle hex key, give each bolt a sharp tap using a hex
key and pin hammer. This should help to break the bond between the steel bolt
and crankcase aluminium. Remove the c/case end plate using a flat section of
metal or use the special tool, -
refer to spare parts list - it will come off easy.
Use the end of a plastic toothbrush to push out the piston sleeve
from the under side. Next is the piston with con rod.
That’s the easy bit.
To
remove the c/shaft, first remove the prop driver.
Not so easy. Ideally
you should have a ball joint remover - from an auto store (about £2.50) -
grind open to suit the size of the prop driver.
Hook on to prop driver; make sure the ball joint remover is
correctly aligned to the prop driver and crankshaft, tighten the bolt against the end of the c/shaft
and out pops the prop driver.
After
taking out the prop driver and split-tapered collet, the c/shaft
should slip out. When refitting the piston sleeve make sure it is perfectly
vertical into the crankcase. It
is a very exact fit and may feel very tight.
Get it right and it will push in very
easily.
BALL
RACED ENGINES.
Procedure
is the same except to take out the crankshaft. First boil the engine in
water and soap to remove all traces of oil. AN EXTRA PAIR OF HANDS HELPS
with the rest of what has to be done. Gently heat the c/case in the area
of the rear bearing with a hot air gun. IT WILL BE HOT SO USE A PAIR OF
GRIPS ON THE LUG. Gently tap the end of the engine against a block of wood
out will come the c/shaft with rear bearing.
Do not force, or over heat. Allow the crankcase time to expand.
The rear bearing should come free with the crankshaft. If
you apply excessive heat, it will transfer to the ball race and it too
will expand, not what you want. What you do want is for the case to expand
before the bearing, allowing the bearing to come loose. If you force the issue, the bearing will come apart.
IT IS AN EXPENSIVE BEARING TO REPLACE.
Now heat front of engine and tap
against a block of wood, out will come the front bearing.
1998
production onwards - crankshaft floats in bearings. Remove c/shaft. Heat
front end of c/case and push out front bearing. To remove rear bearing,
heat c/case and tap the rear of the c/case on wood block and bearing will
fall out. Do not try and forcibly remove the rear bearing. It helps to have the special tools to re-fit.
IF
UNSURE, NEVER EXPERIMENT; GET THE HELP OF AN EXPERIENCED ENGINE MAN TO DO
IT FOR YOU.
Re-fitting
is the exact reverse. Place
the rear bearing on the c/shaft and pop back into c/case. Heat the c/case
and the bearing will fit in. Leave
to cool and the c/case will contract and grip the bearing. Now heat the
front of the c/case and push in the front bearing.
It may need to be tapped in. Do
however insert a nut , old bearing or a very thick washer over the bearing
and then use a pin hammer to tap in - gently
does it.
NOTHING SPECIAL ABOUT THE
PROCEDURES - IT APPLIES TO MOST ENGINES.
When
bolting down the head, remember, 1/8 turn each time otherwise you could
distort the head. It is
always a good idea to fit new head bolts. Now oil the innards of the
engine before tuning over the crankshaft.
REPAIRS SERVICE
- if sending an engine to us for repairs, customers outside the EEC please
ensure you correctly declare the item on the Customs declaration form as "
item returned for repair, no commercial value". Failure to do so could
result in UK Customs and Excise raising a charge for import taxes and taxes.
We only charge for the parts needed, if the cost of the parts exceed 75% of
the value of a new engine, we send a a new engine. If you think that the
fault is covered by our life time warranty against defects, then declare the
item as "engine returned for warranty repair, no commercial value". |
