9)
Always wear close-fitting, well-fastened clothes when starting or operating the running engine. Never wear
loosely hanging clothes (ties, scarf, etc.).
10)
Never try to stop the engine by any part of your body.
11)
Always stop the engine either by turning off the ignition switch or by completely closing the carburetor
throttle valve.
12)
Before starting the engine always make sure that the model is safely fixed in place and cannot start moving.
13)
Fuel is combustible and therefore must be kept in an enclosed container at a safe distance from the engine
when it is running.
14)
When preparing fuel carefully follow the manufacturer’s or dealer’s instructions.
15)
Small objects must be kept at a safe distance from the engine when it is running. Never throw any objects
towards the spinning propeller.
16)
Be careful in choosing the location where you wish to start the engine. Avoid dusty or sandy areas.
17)
Start the engine in well-ventilated areas only. Never start the engine indoors.
18)
When starting the engine make sure that bystanders, especially children, are at a safe distance of at least 10
meters.
19)
The engine power output makes it possible to fly big models. Mal-operation of such models may cause
serious damage. Start using the MVVS 26 or 35 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.
MVVS 26 and 36 has been designed to generate maximum power at 8500 RpM, according to the type of exhaust used. If
you wish to utilize the maximum power output, choose a propeller which allows the engine to reach these revolutions, or
slightly lower revolutions (given the unloading of the propeller depending on the speed of flight) on the ground.
We do not recommend to use propellers with which the engine reaches more than 9000 RpM. on the ground.
Suggested propeller dimensions:
MVVS 26:
MVVS 35:
16x8, 16x10, 16x11, 16x12, 17x8, 17x10, 17x 12, 18x8
18x8, 18x10, 20x8, 20x10, 20x12,21x8, 21x10
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.
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.
Assembly
Since air is used to cool the engine, sufficient air circulation under the cowl must be ensured. Never forget about a hot air
outlet – which must be bigger than the intake. Gas engines heat up to a much greater degree than methanol ones!
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.
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 brand-name MVVS engines with
which you also get the power output guaranteed.
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.
3270 (3271) – compact, medium level of power output
3266 (3268) – tuned pipe, with adaptor 3265 (3269) provides the highest power output, with the flat torque curve, useful
for the model planes
3266 - 3268
3270 – 3271
3265 - 3269
Carburetor adjustment
adjusting needle ( L ) for low RpM range 1 turn and 50 minutes
adjusting needle ( H ) for high RpM range 1 turn and 35 minutes
for WT 793
Basic setting:
adjusting needle ( L ) for low RpM range 1 turn and 45 minutes
adjusting needle ( H ) for high RpM range 1 turn and 45 minutes
for WT 561
(Minutes refer to hands of a clock)
Walbro WT 561 and 793
The new engine comes adjusted to the basic setting.
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
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.
Choke
H needle
adjusting screw
L needle
adjusting screw
Lever - throttle
Pressure pulse inlet