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Operating instructions
MVVS 152 IRS No: 3011
MVVS 152 IRS Twin Spark No: 3011TS
Before using the engine, please read these instructions carefully.
Congratulations on choosing the gas engine MVVS 152cc.
MVVS 152cc has been designed and manufactured for propeller-powered radio-controlled
model planes. It is able to meet all of your expectations of an acrobatic racing engine.
Technical specifications
Bore 48 mm RpM range 1000 – 7500 RpM
Stroke 42 mm
Version 1.3
Weight of complete
engine without ignition*
3530 g Fuel
Unleaded 95-octane
fuel
Weight of ignition unit 270 g Lubrication
* Some manufacturers state the weight of incomplete engines. The value in the table above
stands for the weight of a completely assembled engine, including the spark plug, carburetor,
drive washer and prop screws.
Safety precautions
1) Never use the engine for any manned vehicles.
2) When operating model planes, always follow the rules and laws in effect in your country.
3) The manufacturer declines all responsibility for all damages arising from the operation of
models and other appliances driven by MVVS 152cc engine.
4) Use always original spare parts.
5) Never tamper with the engine construction.
6) Before each flight check that all the propeller screws are tightened up and in good
condition. If you use a spinner, check that it is tightened up too. When mounting the
spinner always follow the assembly instructions.
7) Periodically check that the engine is firmly fixed to the engine mounts. Never start a loose
engine!
8) Always use a balanced propeller! Always replace the propeller when damaged!
9) Make sure that no part of your body intersects the plane of the spinning propeller.
10) Always wear close-fitting, well-fastened clothes when starting or operating the running
engine. Never wear loosely hanging clothes (tie, scarf, etc.).
11) Never try to stop the engine by any part of your body.
12) Always stop the engine either by turning off the ignition switch or by completely closing
the carburetor throttle valve.
Oil with petrol in
mixture 1:40
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13) Before starting the engine always make sure that the model is safely fixed in place and
cannot start moving.
14) Fuel is combustible and therefore must be kept in an enclosed container at a safe distance
from the engine when it is running.
15) When preparing fuel carefully follow the manufacturer’s or dealer’s instructions.
16) Small objects must be kept at a safe distance from the engine when it is running. Never
throw any objects towards the spinning propeller.
17) Be careful in choosing the location where you wish to start the engine. Avoid dusty or
sandy areas.
18) Start the engine in well-ventilated areas only. Never start the engine indoors.
19) When starting the engine make sure that bystanders, especially children, are at a safe
distance of at least 10 m.
20) The engine power output makes it possible to fly big models. Mal-operation of such
models may cause serious damage. Start using the MVVS 152 cc in model planes only
after you have mastered operating smaller models.
Selecting a suitable propeller
It is usually the case that propellers of the same dimensions coming from different
manufacturers are not the same. Oftentimes not even propellers of the same dimensions
produced by a same manufacturer are not the same. The engine power is best utilized when the
propeller dynamics curve and engine power curve (revolutions/power output) intersect in the
area of the engine top power output. Unfortunately, no propeller manufacturer provides this
information. Engine power output is also a variable quality. It depends above all on the
silencer used and can considerably vary. The situation is further complicated by environmental
parameters (temperature and atmospheric pressure in particular): low temperature and high
pressure increase propellers’ input requirements by 20% in comparison with input at hot
weather.
Suggested propeller dimensions: two blade: 30x12, 32x10-12
three blade: 29x12 N
These values are only approximate and may vary with the factors described in the previous
section, as well as with the type of the exhaust system used.
The MVVS 152 is designed for the power maximum by 5800 – 6300 RpM (according the
exhaust pipe used). If this maximum performance is needed, choose the suitable propeller so,
the engine reach these speed on the ground (in fact slightly lower; depends on the unloading
the propeller in air in accordance to reached speed while flying)
We do not recommend use of propellers, which allows turning the engine on the ground more
as 7000 RpM.
Fuel
Always use unleaded 95-octane petrol mixed in the proportion 40 volume units of petrol to 1
unit of Mobil Racing 2T oil. If necessary, quality brand-name synthetic oil intended for
racing two-stroke engines can be used too.
For running the engine in, please use MVVS Racing 2T oil that comes with the engine. Mix it
in the proportion 30:1.
Never use inexpensive oil developed for garden appliances or synthetic oils intended for the
operation of methanol model engines. The manufacturer declines all responsibility for all
engine damages arising from the use of low-quality fuel.
Store fuel in containers designed for this purpose. Do not use mixed fuel older than 90 days.
Assembly
The engine is fastened to place by four holders built in the rear cover. The engine can be
mounted directly to the firewall or an assembly kit can be used (special accessories). Use
screws M6. If you decide to fasten the engine using flexible motor mounts, always choose
parts with enough solidity and strength. Make sure to secure the screws against loosening and
regularly check that they are tightened up and in good condition.
Since air is used to cool the engine, sufficient air circulation under the cowl must be ensured.
Never forget about hot air outlet – which must be higher than the intake one. Gas engines heat
up to higher degree than methanol one!
Do not forget that the engine needs oxygen from the air to be able to operate. Therefore ensure
access of air to the engine intake as well. Caution: intake of warm air from beneath the cowl
may cut the engine power output.
For fuel supply use the hose delivered only, this diameter ensure the sufficient fuel supply in
each turn and minimize the flow resistance. Use of the smaller hose can cause engine turn off
by the turning with high G-forces.
Caution! When mounting the engine in the model use seals to protect all openings and
prevent the pollution of the engine’s inside with sawdust, residual abrasives etc.
Exhaust
Use only factory-made exhausts pipes designed for this type of engine. Preferably MVVS
exhaust system, which also guarantees the announced power output. The manufacturer
declines all responsibility for all engine damages arising from the use of improper exhaust
systems.
When mounting the exhaust follow the manufacturer’s instructions. Make sure to secure
sufficient cooling of the exhaust.
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Carburetor adjustment
Carburetor is adjusted before you buy it. It is not usually needed to change this setting (always
apply if used recommended exhaust system and propeller). In most common flights you will
need to set up the main nozzle only (except races).
Caution!!! The engine must be stopped while you adjust the carburetor in order to prevent
injury by the propeller.
Basic setting:
- adjusting needle (L) for low revolutions range: 1 turn
- adjusting needle (H) for high revolutions range: 1 turn
(the values are derived from the position of clock-hands, starting position: fully closed needle)
The new engine comes adjusted to the basic setting. This setting should be kept during the
engine running in!
Pressure inlet
Throttle lever
Idle screw
Choke lever
Adjusting needle (H)
Adjusting needle (L)
Caution! Newer turn the needles tight, the seat can be so damaged and the carburetor is no
more possible to set, must be replaced for the new ones.
After the engine has been run in, adjust it following the instructions below:
- start the engine and warm it up
- let the engine run at idle speed for approx. 5 seconds
If the engine starts to run backwards do not open the throttle - stop the engine immediately!
Otherwise the engine could be damaged!
Step I
Accelerate to 2/3 of the throttle range within approx. 1 sec (faster acceleration).
Repeat three times – if the engine accelerates quickly and without a hiccup go to Step III. If
acceleration is not smooth go on to Step II.
Step II
Faulty acceleration with hiccups and a tendency to cut out is usually attributable to a
poor fuel mixture in the medium-revolutions range. Stop the engine and recheck the fuel feed
(the hose-pipe must not be pinched or broken; if fitted, check also the fuel filter permeability).
Restart the engine and test acceleration again. If problems persist adjust the carburetor. Open
the adjusting needle L by 5 min and retest acceleration. If acceleration is smooth, open the
needle by another 3-5 min - this should be done because the needle was previously set at a
boundary value; if atmospheric conditions changed during flight, the problems might recur.
If the engine continues to malaccelerate open the needle by 10 min if the engine’s
operation does not improve, stop it and check the basic setting. Set the adjusting needle L at 1
turn and the adjusting needle H at 1 turn . Restart the engine and test acceleration. If the engine
runs correctly go to Step III. If it continues to malaccelerate, open the needle by another 10
min. If it keeps malaccelerate, the defect is likely to lie elsewhere than in incorrect adjustment.
In such a case, go to the section on problem solving.
Step III
If the engine accelerates correctly, according to the above test, set it at idle speed and
accelerate to full speed. Repeat twice more. If the engine functions correctly, go to Step IV. If
it cuts out, open the L needle by 5-10 min more.
If the engine does not respond to acceleration fast enough keep closing the L needle
until the engine starts to cut out in response to gas. At that point reopen the L nozzle by 5-10
min.
Step IV
If the engine reacts correctly set it at full speed. If revolutions do not drop, the engine
has been adjusted successfully. If revolutions seem to drop, open the adjusting needle H by
approx. 5-10 min.
Caution!!! Never close the choke valve completely when the engine is operating!
The choke valve is set to allow minimum air flow only when fully closed, which could cause
damage to the intake reed valve.
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Starting and running in a new engine
Before you first start the engine, screw the plug in and tighten it up. Follow the instructions on
the box of the spark plug. Make sure that the plug socket is fitted in place and fastened down
properly; pull the wire ring over the hexagon.
Fix the ignition sensor in proper position above the magnet with screws enclosed.
Unless the spark plug is not inserted in plug socket, never turn the engine with ignition
turned on. This could lead to ignition damage!
1) Make sure that the ignition is switched off, the choke valve is closed and the throttle valve
is about half opened. Then give the engine 3-4 turns, provided that carburetor is not
overflowing. If it is overflowing, give the engine 1-2 turns only.
2) Switch the ignition on, open the choke valve, set the throttle at slightly higher idle speed
and give the engine a few quickly turns. If even after the fourth turn, with the choke valve
closed, you do not hear a suggestion of the engine starting, give the engine 2 turns following
the instructions in paragraph 1 above. Then proceed according to instructions given in
paragraph 2.
3) If the engine does not start even after another set of turns open the throttle to maximum and
give the engine approx. 4 turns. Switch the ignition off and on again and restart the engine
with throttle turned slightly down and the choke valve set open.
4) If the engine still would not start, unscrew the plug and check its contacts. Clean any
possible petrol moisture ( i.e. an indication of engine overflow ) and screw it in again. Further
starting should only be done with the throttle turned down. If the plug is dry then probably not
enough fuel has been drawn into the carburetor. If that is the case, check the fuel feed and then
return to the instructions given in paragraph 1.
If the engine starts to run backwards do not open the throttle - stop the engine immediately!
Otherwise the engine could be damaged!
While the engine has been started, leave it run for approx. 5 min at a higher idle speed. Then
run it in for approx. 20 min, while changing revolutions from idle to 1/2-3/4 of the range and
shortly holding each position - gradually prolong the holding periods. After 10 minutes
running, start opening the throttle at maximum for short periods of time. Stop the engine and
let it cool down. Then restart it and check the adjustment. If everything is all right, you can
first take off. During first few flights do not overload the engine and do not let it run at high
revolutions for long periods of time (very important at hot weather). Use up all fuel that was
produced as a mixture with the oil that is included in the package. From now on, fuel and oil
should be mixed in the proportion 40:1.
• DO NOT PROCESS THE RUNNING-IN AT IDLE SPEED!
• A COLD ENGINE SHOUL BE WARMED UP BY SHORT ACCELERATIONS
(1-2 SEC)
Problem guide
The engine would not start:
– check the battery voltage; use the good brand battery only
– check and or replace the spark plug if needed (Check the spark by inserting the plug
into the plug socket and turning the engine. The correct electrode spacing is
0,6mm.)
– check the fuel supply
– turn the engine to check its mechanical condition
– check whether the carburetor nozzles are adjusted correctly
– take the carburetor off and visually examine the condition of the carbon-fiber reed
valve
– unscrew the carburetor cover on the side of the pressure inlet, check the fuel screen
possibly give the carburetor a blow with a current of air; when reassembling, make
sure you arrange the membrane and gasket in a correct order
– recheck the pressure hose attached to the carburetor
Replacing the reed valve:
– unscrew and remove the carburetor (mind the gasket)
– unscrew four M4 screws on the flange, remove the flange and take off the reed
valve (mind the gasket)
– unscrew four M2 screws and remove the old valves, replace them with new ones,
screw the screws back in and tighten them gently
– when reassembling, make sure you fix the gasket correctly
Mechanical faults of the engine must always be commit to a professional service
department!
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Service information
After each 20 hours of running or 1 year change the spark plug.
After each 50 hours of operation time preventively check up the con-rod and the reed valve.
After 300 hours of operation time commit the engine to the professional warranty service
department.
After each 3 running hours or every 15th flight do lubricate the front bearing. The new engine
lubricate EARLIEST after first 10 running hours!
Lubrication the engine´s front bearing:
Inject 1.5ml of oil for engines to the hole as on the picture.
During the lubrication DO NOT turn with the propeller!
NOTE! After the bearing lubrication the engine can produce more smoke!
Do not forget to apply the screw-cap into the hole. Running engine without can cause
engine´s damage!!!
Spare parts list
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Nr. Description Nr. Description
0101 Crankcase 1102 Drive washer key
0102 Crankcase screws-set 1103 Propeller nut
0104 Spacer sleeve 1104 Propeller washer
0202 Front bearing 1105 Propeller screw
0203 Rear bearing 1107 Propeller screws - set
0204 Packing 0306 Carburetor flange
0205 Rear needle bearing 0307 Carb. flange gasket
0304 Pressure nipple 0308 Carb. flange screws - set
0305 Pressure nipple gasket 1301 Reed valve case
0401 Cylinder 1302 Reed valve
0402 Cylinder screws - set 1303 Reed valve screws
0403 Cylinder nut 1304 Reed valve gasket-upper
0404 Cylinder gasket 1305 Reed valve gasket-bottom
0405 Exhaust screws - set 1306 Reed valve strap
0406 Exhaust nut 1307 Carburetor screws
1300
0407 Exhaust flange gasket
0701 Piston
0702 Piston ring
0801 Piston pin 3314B Electronic ignition unit
0802 Piston pin retainer 3309 Spark plug
1001 Crankshaft 1405 Ignition sensor fixing screws
1101 Drive washer 3228 Carburetor
= 1301 + 1302 + 1303 + 1305 +
(set)
1306
Warranty
The MVVS gas engines come with a three-year guarantee against defects in workmanship and
materials. Only original buyers of the engines are eligible warranty claimants. The warranty
cannot be transferred with a change in ownership.
This guarantee does not cover:
- any normal wear that might occur
- damage arising from accidents
- damage arising from the use of an unbalanced or damaged propeller
- damage arising from the use of a too small or a too big propeller
- damage arising from the use of low-quality fuel
- damage arising from the use of other than original spare parts and accessories
- damage arising from sucking a foreign object into the engine
- damage arising from any improper use
For further questions, please contact:
MVVS, spol. s r.o., tr. Kpt. Jarose 35, 602 00 Brno, Czech Republic
Tel. +420 545 211 683, fax: +420 545 211 418
E – mail: mvvs@mvvs.cz
Web: www.mvvs.cz
Certificate of Warranty
Date: Serial number:
Buyer’s name and address:
Dealer:
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