It is of vital importance, before attempting to operate
your eng ine, to read the gene ral 'SA FETY
INSTRUCTIONS AND WARNINGS' section on
pages 2-5 of this booklet and to strictly adhere to the
advice contained therein.
Also, please study the entire contents of this
instruction manual, so as to familiarize yourself
with the controls and other features of the engine.
Keep these instructions in a safe place so that you
may readily refer to them whenever necessary.
It is suggested that any instructions supplied with
the vehicle, radio control equipment, etc., are
accessible for checking at the same time.
1
2-5
6-7
8
9
10-11
12
13-14
15
16
17
18-24
25-28
29-32
33-35
36-41
42-43
44-45
46-48
CONTENTS
SAFETY INSTRUCTIONS AND
WARNINGS ABOUT YOUR O.S. ENGINE
ENGINE CONSTRUCTION, NOTES WHEN
APPLYING AN ELECTRIC STARTER
INSTRUCTIONS
BASIC ENGINE PARTS
TOOLS, ACCESSORIES, etc.
STANDARD ACCESSORIES
CARBURETOR CONTROLS,
INSTALLATION OF THE CARBURETOR
NOTES CONCERNING THE RECOIL STARTER
GLOWPLUG
ENGINE INSTALLATION
STARTING THE ENGINE &
RUNNING-IN ('Breaking-in)
FINAL ADJUSTMENT
TROUBLE SHOOTING
CARE AND MAINTENANCE
EXPLODED ENGINES VIEWS & PARTS LIST
CARBURETOR EXPLODED VIEW &
PARTS LIST
O.S. GENUINE PARTS & ACCESSORIES
THREE VIEW DRAWING
2
!
!
Remember that your engine is not a "toy", but a highly efficient internalcombustion machine whose power is capable of harming you, or others, if it is
misused. As owner, you, alone, are responsible for the safe operation of your
engine, so act with discretion and care at all times.
If at some future date, your O.S. engine is acquired by another person, we would
respectfully request that these instructions are also passed on to its new owner.
SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE
The advice which follows applies basically to ALL MODEL ENGINES and is
grouped under two headings according to the degree of damage or danger
which might arise through misuse or neglect.
WARNINGS
NOTES
These cover events which might involve
serious (in extreme circumstances, even
fatal) injury.
These cover the many other possibilities,
generally less obvious sources of danger,
but which, under certain circumstances,
may also cause damage or injury.
3
!
WARNINGS
Model engine fuel is poisonous. Do not allow it to
come into contact with the
eyes or mouth. Always store
it in a clearly marked container and out of the reach
of children.
Model engine fuel is also
highly flammable. Keep it
away from an open flame,
excessive heat, sources of
sparks, or anything else
which might ignite it. Do not
smoke or allow anyone else
to smoke, near to it.
Never operate your engine in an enclosed space. Model engines, like
automobile engines, exhaust deadly
carbon-monoxide. Run your engine
only in an open area.
Model engines generate
considerable heat. Do not
touch any part of your
engine until it has cooled.
Contact with the muffler
(silencer), cylinder head
or exhaust header pipe, in
particular, may result in a
serious burn.
•
•
•
•
4
!
NOTES
Before starting the engine, always check
the tightness of all the screws and nuts
especially those of joint and movable
parts such as throttle arm. Missing
retightening the loose screws and nuts
often causes the parts breakage that is
capable of harming you.
This engine is intended for model cars.
Do not attempt to use it for any other
purpose.
Mount the engine in your model
securely, following the manufacturer's
recommendations, using appropriate
screws and locknuts.
Install an effective silencer (muffler).
Frequent close exposure to a noisy
exhaust (especially in the case of the
more powerful highspeed engines) may
eventually impair your hearing and such
noise is also likely to cause annoyance
to others over a wide area.
The wearing of safety glasses is also
strongly recommended.
Take care that the glowplug clip or
battery leads do not come into contact
with rotating parts. Also check that the
linkage to the throttle arm is secure.
For their safety, keep all onlookers
(especially small children) well back (at
least 20 feet or 6 meters) when
preparing your model for running.
5
!
NOTES
To stop the engine, fully retard the
throttle stick and trim lever on the transmitter, or, in an emergency, cut off the
fuel supply by pinching the fuel delivery
line from the tank.
Warning! Immediately after a glowplugignition engine has been run and is still
warm, conditi ons s ometimes exist
whereby it is just possible for the engine to
abruptly restart if it is rotated over
compression WITHOUT the glowplug
battery being reconnected.
Pull the operating handle straight out
when starting the engine, so that the cord
does not rub against the vehicle body or
engine. This will help prevent the cord
from being damaged by abrasion or
engine heat.
Do not extend the starter cord more than
40cm (16"). Do not abruptly release the
operating handle. Allow the cord to
rewind smoothly while still holding the
handle.
Do not attempt to disassemble the recoil
starter of the 21VG-PX.
If you do so, the very strong spring inside
will be suddenly ejected. This can be
very dangerous.
6
Piston
Cylinder Liner
Crankshaft
ENGINE CONSTRUCTION
With this engine, the piston
will feel tight at the top of its
stroke (TDC) when the engine
is cold.
This is normal.
The cylinder bore has a
slight taper.
The piston and cylinder are
designed to achieve a perfect
running clearance when they
reach operating temperature.
Near TDC
Slight taper
When the engine is cold.
When the engine is hot.
7
Notes when starting the engine
Do not over-prime.
This could cause a hydraulic lock
and damage the engine on
application of the electric starter or
recoil starter.
If over-primed, remove glowplug,
close the needle-valve and apply
starter or pull recoil starter to
pump out surplus fuel.
Cover the head with a rag to
prevent any pumped out fuel from
getting into your eyes.
Remove the glowplug.
Pump out surplus fuel.
Install the glowplug.
8
This manual handles the following
three versions.
MAX-21VG SERIES INSTRUCTIONS
NOTE
As delivered, the engine has its
carburetor lightly fit into its intake.
Secure it according to the INSTALLATION
OF THE CARBURETOR section.
MAX-
21VG-P
with 21F carburetor
The 21VG Series engines are developed for
1/8 scale R/C cars. They are rear exhaust
engines designed for sport use.
For easier handling newly designed 21F
carburetor these engines are equipped with
a and also a No.8 glowplug is supplied.
They have mild and smooth accelerating
characteristics which are most suitable for
sport runs. Recoil starter incorporated
versions which eliminate the need for a
separate electric starter and starter battery
are also available.
MAX-21VG-PX
with 21F carburetor
(Pilot Shaft)
(Pilot Shaft, with recoil starter)
About pilot shaft
Both engines are equipped with Pilot Shaft
crankshafts for use with the Centrax type
clutch. These are also known as "SG" shafts.
MAX-
21VG-P ES
with 21F carburetor
(Pilot Shaft, for Roto Starter)
ROTO STARTER is the product name of HPI RACING.
9
MAX-21VG-PX
Heatsink Head
Carburetor
Type 21F
Crankshaft
Crankcase
Mounting Lugs
Exhaust
Starter Handle
Recoil Starter
Assembly No.N3
Rear Adaptor
BASIC ENGINE PARTS
10
Items necessary for starting
TOOLS, ACCESSORIES, etc.
The following items are necessary for operating the
engine.
FUEL
Generally, it is suggested that the user selects a fuel
that is commercially available for model two-stroke
engines and contains 10-30% nitromethane.
As a starting point, we recommend a fuel containing
20% nitromethane, changing to a fuel containing more
nitro if necessary. When the brand of fuel is changed,
or the nitro content increased, it is advisable to repeat
the running-in procedure referred to in the RUNNINGIN paragraphs.
Please note that with high-nitro fuels,
although power may be increased for
com pe tition purposes , glow pl ug
elements do not last as long and
engine life will be shorter.
!
REMINDER!
Model engine fuel is poisonous. Do not
allow it to come into contact with the eyes
or mouth. Always store it in a clearly
marked container and out of the reach of
children.
!
Model engine fuel is also highly flammable.
Keep it away from open flame, excessive
heat, sources of sparks, or anything else
which might ignite it. Do not smoke or allow
anyone else to smoke, near to it.
GLOWPLUG IGNITER
Commercialy available handy
glowplug heater in which the
glowplug battery and battery leads
are integrated.
FUEL FILTER
To be installed in the fuel line between
fuel tank and carburetor to prevent
dust from entering the carburetor.
11
FUEL PUMP
For filling the fuel tank, a simple, polyethylene "squeeze" bottle, with a suitable spout, is required.
STARTER BOX
For starting the engine.
It is not necessary for 21VGPX
SILICONE FUEL LINE
Heatproof silicone tubing of approx.
5mm o.d. and 2mm i.d. is required for
the connection between the fuel tank
and engine.
TOOLS
HEX SCREWDRIVER
SCREWDRIVER
Necessary for engine installation.
1.5mm, 2mm, 2.5mm, 3mm
Necessary for carburetor adjustments.
No.1, No.2, etc
LONG SOCKET WRENCH WITH PLUG GRIP
Recommended for easy removal and replacement of
the angled and recessed glowplug, the O.S.Long
Socket Wrench incorporates a special grip.
ROTO START
For starting the 21VG-P ES.
12
MAX-21VG-P, MAX-21VG-PX, MAX-21VG-P ES
Standard accessories
Glow Plug No.8 1piece
Exhaust Seal Ring 1piece
INSTALLING THE GLOWPLUG
Fit washer to glowplug and insert carefully into cylinder-head, making sure that it is not cross-threaded before tightening firmly.
Install the exhaust seal ring supplied.
Exhaust
Seal Ring
Glowplug
Socket
Wrench
Washer
13
CARBURETOR CONTROLS
The Needle-Valve(Adjusted at the factory):
Three adjustable controls are provided on this
carburetor.
For adjusting the mixture strength when the throttle
is fully open.
The Mixture Control Screw
(Adjusted at the factory):
For setting the idle speed:
For adjusting the mixture strength at part-throttle
and idle speed, to obtain steady idling and smooth
acceleration to mid speed.
The Metering Needle
(Adjusted at the factory):
NOTE : Readjustment may b e n ecessary,
occasionally to allow for changes in fuel formula,
gear ratio or clutch engagement point.
Metering Needle
Needle Valve
Ball Link No.5
Dust Cover
Carburetor Type 21F
Fuel Inlet
Needle Holder
Mixture Control Screw
14
INSTALLATION OF THE CARBURETOR
As delivered, the engine has its carburetor lightly fit into
the intake boss. Secure it as follows.
Rotate the retainer screw gently until it stops, then
tighten a further 60-90˚. Do not overtighten the
screw as this will damage the carburetor body.
1.
Rotate the retainer nut
gently until it stops.
Tighten a further 60-90˚
Fuel Inlet
Needle Holder
Ball Link
Retaining Screw
Loosen the retainer screw, rotate the carburetor to
its correct position and make sure that it is pressed
well down into the intake boss, compressing the
rubber gasket, before retightening the screw.
NOTE
As delivered, the engine has its carburetor
lightly fit into its intake. Secure it changing its
angle according to the car chassis.
2.
When changing the ball link direction, loosen the
retaining screw with a 1.5mm Hex wrench.
After changed the fuel inlet direction, tighten the
needle holder slowly and gently until it stops.
Then, tighten 45~60 degrees further. Do not tighten
further or the fuel inlet will be distorted, which may
result in fuel leaking.
15
!
!
!
◆
NOTES CONCERNING THE RECOIL STARTER
REMINDER!
Do not attempt to disassemble the recoil
starter. If you do so, the very strong spring
inside will be suddenly ejected. This can be
very dangerous.
Do not extend the starter cord more than
40cm (1 6"). Do not abruptl y rele ase the
operating handle. Allow the cord to rewind
smoothly while still holding the handle.
Pull the operating handle straight out when
starting the engine, so that the cord does not
rub against the vehicle body or engine.
This will help prevent the cord from being damaged
by abrasion or engine heat.
Try to avoid spilling fuel over the starter unit and its
cord. Some fuels have a detrimental effect on these
parts.
The starter prevents the engine from being rotated
in the wrong direction.The unit will be damaged if you
attempt to force the flywheel in the opposite direction (i.e. clockwise when viewed from the crankshaft
end).
Starter Handle
16" 40cm MAX!
It is suspected that the engine is over-primed when
the pulling load is too heavy to pull the starter. In this
case, refer to page 7 and TROUBLE SHOOTING
about over priming.
16
GLOWPLUG
The role of the glowplug
Glowplug life
Particularly in the case of very high performance
engines,
glowplugs must be regarded as expendable
items. However, plug life can be extended and engine
performance maintained by careful use, i.e.:
Install a plug suitable for the engine.
Use fuel containing a moderate percentage of
nitromethane unless more is essential for racing events.
Do not run the engine too lean and do not leave the
battery connected while adjusting the needle.
With a glowplug engine, ignition is initiated by the
application of a 1.5-volt power source. When the
battery is disconnected, the heat retained within the
combustion chamber remains sufficient to keep the
plug filament glowing, thereby continuing to keep the
engine running. Ignition timing is 'automatic' : under
reduced load, allowing higher rpm, the plug becomes
hotter and, appropriately, fires the fuel/air charge
earlier; conversely, at reduced rpm, the plug become
cooler and ignition is retarded.
Apart from when actually burned out, a plug may
need to be replaced because it no longer delivers its
best performance, such as when:
When to replace the glowplug
Filament surface has roughened and turned white.
Filament coil has become distorted.
Foreign matter has adhered to filament or plug
body has corroded.
Engine tends to cut out when idling.
Starting qualities deteriorate.
Since the glowplug and fuel combination
used may have a marked effect on per-
formance and reliability, it would be
worthwhile to experiment with different plug types. An
O.S. No.8 glowplug is supplied with the engine. Recommended O.S. plugs are the No.8 and A5. Carefully
install plug finger-tight, before final tightening with the
correct size plug wrench.
17
ENGINE INSTALLATION
Make sure that the vehicle's engine mounting surfaces
are level and in the same plane. Poor installation may
cause distortion of the crankcase, bearings, etc.,
resulting in erratic running and loss of performance.
Chassis
Chamfer inside edges of bearers.
Do not allow
bottom of
crankcase to
touch chassis.
The recommended screws for securing the engine are
3mm or 4-40 steel Allen hexagon socket type.
If existing holes in the engine mount do not align
perfectly with engine mounting lugs, enlarge them
slightly with a needle-file so that screws are in
alignment with the mounting holes.
Engine Mount
When installing the engine on the chassis, note the
following points.
(Chamfer inside edges of bearers when the engine
mount edges interfere with the engine. Do not
chamfer the engine.)
File
18
STARTING THE ENGINE & RUNNING-IN ('Breaking-in)
PRESSURIZED FUEL SYSTEM
!
Before starting the engine, always check the
tightness of all the screws and nuts especially those of joint and movable parts such as
throttle arm. Missing retightening the loose
screws and nuts often causes the parts
breakage that is capable of harming you.
Never run your vehicle without installing the air
cleaner. Dust and dirt that may otherwise be drawn
into the engine will rapidly shorten its life.
The somewhat violent changes of vehicle attitude
that occur in off-road running, combined with the
fact that, in buggy type cars, the fuel tank is often
located some distance from the carburetor, means
that fuel 'head' at the carburettor can vary and upset
running.Therefore,it is recommended that a muffler
pressurized fuel feed system be used.
Running- in is a procedure for an engine to come
close to actual running conditions (fuel, r.p.m.,
engine temperature, etc.).
Excessively rich running and prolonged low
speed running should be avoided. Prolonged low
speed running and low temperature running may
result in the oil in the fuel being gelled and
piston/liner being stuck together.
Please do not run on a public street, this
could cause serious accidents, personal
injuries and/or propetry damage.
Please do not run near pedestrians or small
children.
Please do not run in small or confined areas.
Please do not run where loud noises can disturb
others, such as hospitals and residential areas.
While Operating
RUNNING-IN ('Breaking-in)
19
!
Lay the chassis on a stand and start the engine so
that the tires are not in contact with the ground.
The following procedure is suitable when a fuel
containing up to 30% nitromethane is used.
Fill the tank completely with fuel.
Temporarily remove the glowplug to check that it
glows bright red when energized.
Glow Plug Igniter
Pliers
Element glows when
energized.
Replace the plug when the
element does not glow or is
burnt out.
Fuel Pump
Fuel Tank
Do not hold a glowplug with fingers and use
pliers when checking the brightness. Do not
have your face close to the glowplug or boiled
fuel remaining in the coil will burn you.
stand
NOTE:
Be careful not to damage the plug threads when
holding a glowplug with pliers.
20
Turn the needle-valve clockwise until it stops. This
is the fully closed position. Do not force it to turn
further.
Metering needle is set at basic position.
(Refer to P28.)
Needle Valve
Open
Close (clockwise)
approx 0.5mm
The carburetor is set as shown below at the
factory. Start the engine as it is.
The needle-valve is set approx. 3 turns open from
the fully closed position.
Approx. 0.5mm open factory setting
Note
Check the throttle opening at idle before installing
an air cleaner. After the engine is started, be sure
to install an air cleaner.
21
Fuel
Deliver fuel into the carburetor.
Fuel tank side
If the fuel tank is equipped with a choke button, push
the button to send the fuel to the carburetor. If not,
apply an electric starter to send the fuel to the
carburetor.
Switch on the transmitter and make sure that each
linkage moves correctly.
Fuel tank
choke button
Note
If too much fuel is delivered into the engine, the
engine cannot be started due to over-priming.
In this case, refer t o pag e 7 and TROUBLE
SHOOTING about over-priming.
22
Now connect glowplug battery lead to heat
the plug filament and start the engine.
In case of the 21VG-PX
Starter Handle
Pull the starter handle briskly straight out
several times to start the engine.
Start the engine using a starter box, making sure
the engine rotation direction is correct (counterclockwise seen from the crankshaft end).
Be sure to install an air cleaner when starting.
In case of the 21VG-P
16" 40cm MAX!
Do not extend the starter cord more than 40cm
(16").
Glowplug
Igniter
air cleaner
approx 1mm
Set the needle-valve approx. 2.5 turns open from
the fully closed position. (Do not close further.)
Set the throttle opening a little wider that the
factory set by adjusting the Mixture control screw.
When the engines does not start
or stops right after started Try the followings.
In case of the 21VG-P ES
Use the ROTO START to start the engine.
23
When the engine starts, first allow it to operate in
short runs at the very rich starting settings, with
the glowplug battery still connected and the driving
wheels clear of the ground. The rich mixture will,
under these conditions, provide adequate
lubrication and cooling, indicated by profuse
smoke from the exhaust.
It is vitally important to set the
throttle at the correct position
before att empting to start the
engine. If the engine is allowed to
run with the throttle too far open
under "no load" conditions, it will
rapidly overheat and may be
seriously damaged.
Remember!
RPM High
RPM Low
Mixture Control Screw
If the RPM are lowered too much, the engine
stops. Set the idle RPM a little higher when the
engine is new.
Next adjust the idle speed (low engine RPM)
A correct idle means …
Engine is started but the car does not move when the
throttle is positioned neutral.
Disconnect the glowplug battery If the car starts
moving (or tiers rotate), adjust the Mixture control
screw so that tiers may not rotate with steady
idling.
24
Next, disconnect the glowplug battery and tr y
running the car on the track. If the engine stalls,
open the throttle fractionally, but try to keep the
engine running as rich as possible: if it stops
because of being excessively over-rich, close the
Needle-Valve 30˚ and try again.
Run the car on the track until one tank of fuel has been
consumed, then close the Needle-Valve 30˚ and run
the car for 1 full tanks of fuel. Repeat this procedure
until approx. 2 liter of fuel have been consumed,
during which time the throttle may be opened for brief
bursts of increased power. If the engine stops at
medium speeds, close the Mixture Screw 45˚.
Needle
The position of the needle-valve
when starting the engine.
Close the needle-valve approx.
30˚ after running the vehicle for
1 full tanks of fuel.
Repeat this procedure until
approx. 1 liter of fuel have
been consumed.
Note:
In the event of any major working parts (e.g.
piston/cylinder liner assembly) being replaced or the
fuel being changed, especially to high nitro fuel, the
complete running-in should be repeated.
Warning!
Do not touch rotating parts, engine and silencer
when stopping the engine as they become very hot,
and contact with them may result in a serious burn.
To stop the engine, close the throttle to idle speed
and shut it off completely with the trim lever on the
transmitter then cut off the fuel supply by pinching
the fuel delivery tube to the carburetor.
Fuel
How to stop the engine
25
FINAL ADJUSTMENT
Metering
Needle
Open
Close
Close
Open
Needle Valve
Metering Needle
More fuel Less fuel
More fuel
Less fuel
Final adjustment should be carried out only
after the running-in has been completed.
Needle Valve
Mixture Control
Screw
Adjust high RPM running.
Run the vehicle (with throttle fully open) over the
longest available straight course, in order to
observe the model's speed. Next return the car to
the starting point, close the Needle-Valve 30 and
repeat the run, taking note of the improvement in
performance.
Continue with further runs, gradually reducing the
Needle-Valve setting and aiming to achieve the
highest straight-line speed. Remember, however,
that, if the Needle-Valve is shut down too far, the
engine will overheat and, accompanied by visibly
diminished exhaust smoke, the model will lose
speed. At this point, throttle down immediately, stop
the vehicle and reopen the Needle-Valve 45~90 .
26
Carry out adjustments patiently, under actual
running conditions, until the engine responds
quickly and positively to the throttle control.
Adjust medium and low RPM running.
Warning!
Mixture adjustments (whether via the Metering
Needle, or the Needle-Valve) cannot be made
accurately under 'no-load' conditions, which, in
any case, are not advised, since such operation
carries the risk of seriously damaging the engine
through over-revving and overheating.
With the engine running, close the throttle and
allow it to idle for about five seconds, then reopen
the throttle fully. If, at this point, the engine puffs
out an excessive amount of smoke and the
vehicle does not accelerate smoothly and rapidly,
it is probable that the idle mixture is too rich.
In this case, turn the Metering Needle clockwise
45-90 .
If, on the other hand, the engine tends to speed
up momentarily and then cut out abruptly when
the throttle is opened, the idle mixture is too lean.
Correct this by turning the Metering Needle
counter-clockwise 45-90 .
NOTE:
Metering Needle adjustment should be made in
steps of not more than 45-90 , carefully checking
the effect,on throttle response, of each small
adjustment.
27
With the optimum mixture control position, light
smoke is visible during high speed running,and the
engine rpm increases smoothly during acceleration.
Remember that, if the engine is operated with the
fuel/air mixture slightly too lean, it will overheat and
run unevenly.
As with all engines, it is advisable to set both the
needle-valve and meter ing needle or Mixture
Control Screw slightly on the rich side of the best
rpm setting, as a safety measure.
If the engine runs too fast with the throttle closed,
the Mixture Control screw sho uld be turne d
counter-clockwise to allow the throttle opening to
be reduced.
Finally, beyond the nominal break-in period, a
slight readjustment toward a leaner needle setting
may be r eq ui re d t o maintain maximu m
performance.
NOTE
The above mentioned needle opening is a guide. It
varies according to the fuel used and silencer.
Usually, when a lower nitro content fuel used, it will
be necessary to close the needle-valve.
Do not close the needle-valve too much or rust will
be generated and the engine will be damaged.
28
REALIGNMENT OF METERING NEEDLE
In the course of making carburetor adjustments, it
is just possible that the Metering Needle and the
Mixture Control Scr ew may be inadvert ent ly
screwed in or out too far and thereby moved
beyond its effective adjustment range.
The basic positions can be found by rotating the
Metering Needle until its slotted head is flush with
the ball link body.
Slide Valve
Carburetor Body
Metering Needle
Rotate the Metering
Needle until its slotted
head is flush with the
ball link body. This is the
basic position.
Ball Link
Note:
Rea djust ment of the needl e-val ve m ay be
necessary to allow for changes in fuel formula,
gear ratio, clutch engagement point and muffler.
Also, needle setting may vary to atmospheric
conditions within the day. Readjust it according to
actual engine running.
29
TROUBLE SHOOTING
Symptom
Cause Corrective action
Engine fails to fire.
Fuel tank is empty.
Fuel not reaching the engine.
Fill the tank with fuel and repeat
Priming procedure.
Glowplug element is burnt out.
Glowplug battery discharged
Replace glowplug.
Recharge or replace the battery.
Clogged fuel filter
Air cleaner and silencer inside is dirty.
Clean or replace fuel filter.
Replace cleaner element and clean inside silencer.
Over priming Remove glowplug and pump out excess fuel.
Fuel tubing is disconnected.
Connect fuel tubing securely.
Fuel tubing is kinked, split or has a hole.
Check the tubing carefully and replace if necessary.
Incorrect servo linkage Connect correctly after setting servo at neutral.
Reverse rotating direction of starter box.
Mare sure it rotates counter clockwise seen
from crankshaft side.
Recoil starter slips.
Inject cleaner spray into starter cord crevis
on the body.
30
Cause
Corrective action
Engine fires intermittently but does not run.
Insufficient fuel in the tank. Fill the tank with fuel.
Deteriorated glowplug
Replace glowplug.
Clogged fuel filter
Air cleaner and silencer inside is dirty.
Clean or replace fuel filter.
Replace cleaner element and clean inside silencer.
Engine overheated
Wait until engine cools.
Incorrect clutch release
Adjust the tension of clutch spring.
Glowplug battery disconnected too soon.
Do not disconnect plug battery and wait until
r.p.m. becomes stable.
Air bubbles in fuel
Install O rings to the tank screws to prevent
bubbles.
31
Cause
Corrective action
Cause
Corrective action
Unstable idle
Unsuitable glowplug
Use suggested glowplug in the instructions.
Unsuitable fuel
Do not use extremely high nitro or
low oil content fuel.
Extremely light flywheel Add heavier flywheel
Silencer is disconnected or has play
Install silencer securely.
Not reaching expected peak r.p.m.
Insufficient warming up or running-in.
Set the needle only after warming up.
Complete running-in.
Silencer or manifold is not securely connected
or disconnected.
Replace seal ring.
Check the connections and secure them.
Fuel tubing from tank is split or broken.
Replace the tubing.
32
Cause
Corrective action
Cause
Corrective action
Poor response
Deteriorated glowplug
Replace glowplug.
Incorrect carburetor settings
Readjust low r.p.m. range with metering
needle or mixture control screw.
Incorrect setting of transmitter Exponential function.
Check the transmitter setting.
Poor r.p.m. drop
Throttle position open too far.
Close the mixure control screw to adequate
position to lower idle r.p.m.
Carburetor not fully seated
Install carburetor securely.
Incorrect linkage
Make sure the throttle servo linkage does not
bind and is connected correctly.
Metering needle closed too far.
Open the metering needle a little.
33
CARE AND MAINTENANCE
Do not forget to clean the filters regularly to remove
dirt and lint that accumulate on the filter screens.
Also, clean the carburetor itself occasionally.
At the end of each operating session, drain out any
fuel th at may remain in th e fuel t an k.
Afterwards,energize the glow-plug and try to restart
the engine, to burn off any fuel that may remain
inside the engine. Repeat this procedure until the
engine fails to fire. Do this while the engine is still
warm.
Care and maintenance after the running is very
important. Be sure to carry out the following
procedures.
34
Then, inject some after-run oil into the engine, and
rotate the engine with an electric starter or the
recoil starter for 4 to 5 seconds to distribute the oil
to all the working parts.
Finally, when cleaning the exterior of the
engine, use methanol. Do not use gasoline
or any solvent that might damage the silicone
fuel tubing.
Note:
Do not inject after-run oil into the carburetor as
this may cause the O-rings inside the carburetor
to deteriorate. These procedures will reduce the
risks of starting difficulties or corrosion after a
period of storage.
35
The minute particles of foreign matter, that are present
in any fuel may, by accumulating a nd partially
obstructing fuel flow, cause engine performance to
become erratic and unreliable.
O.S. 'Super-Filters' (large and small) are available, as
optional extras, to deal with this problem.
One of these filters installed to the pickup tube inside
your refueling container, will prevent the entry of
foreign material into the fuel tank. It i s al so
recommended that a good in-line filter be installed
between the tank and carburetor.
Dirt and dust may lodge in marked places.
CHECKING THE ENGINE
If the engine suffers a loss of performance after a
long period of running it may be due to the wearing of
parts. It is suggested that the worn par ts be replaced
when the following symptoms are detected.
Engine sound changes and easily overheats.
Power has dropped considerably.
Idle is unstable and/or engine tends to stop
at idle.
In most cases, ball bearings, cylinder & piston assembly,
connecting rod and/or crankcase have become worn
out or abnormal. Check the parts carefully and replace
them if necessary.
36
C.M3x18
1
2
3
5
4
6
7
8
9
10
11
12
14
13
C.M2.6x7
C.M2.6x15
12-1
21VG-P ENGINE EXPLODED VIEW
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw
F...Flat Head Screw N...Round Head Screw S...Set Screw
37
21VG-P ENGINE PARTS LIST
The specifications are subject to alteration for improvement without notice.
123456789
101112
12-1
13
14
23604100
23613000
23906000
21817000
23605010
23618030
23618171
23731000
23611000
23430000
23612000
23614100
23764020
23617000
23763010
71608001
22826140
Description
Code No.
No.
Heatsink Head
Cylinder & Piston Assembly
Piston Pin
Piston Pin Retainer (2pcs.)
Connecting Rod
Carburetor Complete (Type 21F)
Carburetor Retainer Assembly
Crankshaft Ball Bearing (Front)
Crankcase
Crankshaft Ball Bearing (Rear)
Crankshaft
Gasket Set
Cover Gasket
Cover Plate
Screw Set
Glow Plug No.8
Exhaust Seal Ring
38
C.M3x18
1
2
3
5
4
6
7
8
9
10
11
14
13
C.M2.6x15
16
M.+M2.6x7
M.+M2.6x6
15-1
15-2
15
12
12-1
21VG-PX ENGINE EXPLODED VIEW
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw
F...Flat Head Screw N...Round Head Screw S...Set Screw
39
21VG-PX ENGINE PARTS LIST
The specifications are subject to alteration for improvement without notice.
123456789
101112
12-1
131415
15-1
15-2
16
23604100
23613000
23906000
21817000
23605010
23618030
23618171
23731000
23611000
23430000
23612010
23614100
23764020
23612050
23611800
73009000
73009100
73008200
23911300
71608001
22826140
Heatsink Head
Cylinder & Piston Assembly
Piston Pin
Piston Pin Retainer (2pcs.)
Connecting Rod
Carburetor Complete (Type 21F)
Carburetor Retainer Assembly
Crankshaft Ball Bearing (Front)
Crankcase
Crankshaft Ball Bearing (Rear)
Crankshaft
Gasket Set
Cover Gasket
Starting Shaft
Rear Adaptor
No.N3 Recoil Starter Assembly
No.N3 Recoil Starter Body
One-way Clutch
Screw Set
Glow Plug No.8
Exhaust Seal Ring
Description
Code No.
No.
40
21VG-P ES ENGINE EXPLODED VIEW
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw
F...Flat Head Screw N...Round Head Screw S...Set Screw
C.M3x18
1
2
3
5
4
6
7
8
9
10
11
14
13
C.M2.6x15
17
M.+M2.6x7
12
12-1
15
C.M2.6x7
C.M2.6x12
16
41
21VG-P ES ENGINE PARTS LIST
The specifications are subject to alteration for improvement without notice.
Heatsink Head
Cylinder & Piston Assembly
Piston Pin
Piston Pin Retainer (2pcs.)
Connecting Rod
Carburetor Complete (Type 21F)
Carburetor Retainer Assembly
Crankshaft Ball Bearing (Front)
Crankcase
Crankshaft Ball Bearing (Rear)
Crankshaft
Gasket Set
Cover Gasket
Starting Shaft (For Roto Start)
Rear Adaptor (For Roto Start)
One-way Clutch
ES Starter Assembly
Screw Set
Glow Plug No.8
Exhaust Seal Ring
Description
Code No.
No.
123456789
101112
12-1
1314151617
23604100
23613000
23906000
21817000
23605010
23618030
23618171
23731000
23611000
23430000
23612010
23614100
23764020
23912210
23917210
73008200
73009200
23911300
71608001
22826140
42
21F CARBURETOR EXPLODED VIEW
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw
F...Flat Head Screw N...Round Head Screw S...Set Screw
1
2
3
5
4
6
7
8
S.M3x3
2-2
2-1
2-4
2-3
5-1
1-1
43
21F CARBURETOR PART LIST
The specifications are subject to alteration for improvement without notice.
1
1-1
2
2-1
2-2
2-3
2-4
3
4
5
5-1
6
7
8
22848160
27881820
23618190
23618197
46066319
23619194
23818176
23618130
23981210
23981510
27881820
23981520
23781400
29015019
Description
Code No.
No.
Mixture Control Screw
"O" Ring (2pcs.)
Needle Valve Assembly
Needle Assembly
"O" Ring (2pcs.)
Needle Holder Assembly
Fuel Inlet
Carburetor Body
Slide Valve
Metering Needle Assembly
"O" Ring (2pcs.)
Dust Cover
Ball Link (No.3)
Carburetor Rubber Gasket
44
(72106440)
(72101272)
(22826140)
(72106130)
(22826140)
(72106042)
(72106430)
(72101272)
(22826140)
(72106090)
(71608001)
No.8
(71605100)
A5
O.S.
Glow Plug
Exhaust Seal Ring
(2pcs.)
Joint Spring (3pcs.)
Header Pipe Spring
(2pcs.)
Exhaust Seal Ring
(2pcs.)
M2000 Exhaust
Header Pipe Assembly
T-2060WN Tuned
Silencer Assembly
M2000SC Exhaust
Header Pipe Assembly
Header Pipe Spring
(2pcs.)
Exhaust Seal Ring
(2pcs.)
T-2060SC WN Tuned
Silencer Assembly
(72106135)
(72106130)
(72106440)
T-2060SC WN
Tuned Silencer Assembly
M2000SC Exhaust
Header Pipe Assembly
T-2060SC WN Complete Set
(22826140)
Exhaust Seal Ring
(2pcs.)
SUPER JOINT TUBE 21
(72106300)
45
(71521000)
(79871020)
(79871040)
(72106120)
3
(73300305)
8
(73300812)
16
(73301612)
18
(73301812)
M2.6x7
M2.6x12
Dust Cap Set
Cap Screw Set
(10pcs.)
The specifications are subject to alteration for improvement without notice.
Long Socket Wrench
With Plug Grip
(5pcs.)
(3pcs.)
(3pcs.)
(3pcs.)
Joint tube type
(For 21-30)
T-2070 Tuned Silencer
On-road Type
(72412000)
(72412100)
(72412200)
(72413000)
(72413200)
SUPER AIR CLEANER 203
203 Filter Element (4pcs.)
Super Air Cleaner 202
202 Cleaner Body
202 Filter Element (4pcs.)
Off-road Type
(79871050)
M2.6x15
(79871180)
M3x18
46
3.46 cc (0.211 cu.in.)
16.6 mm (0.654 in.)
16.0 mm (0.63 in.)
3,000-36,000 r.p.m.
2.0 ps / 30,000 r.p.m.
347 g (12.24 oz.)
■
■
■
■
■
■
UNF1/4-28
30.8
45
87.4
21.6
44
29.5
21
37
4- 3.3
54
SPECIFICATIONS
21VG-P THREE VIEW DRAWING
Displacement
Bore
Stroke
Practical R.P.M.
Power output
Weight
Dimensions (mm)
47
3.46 cc (0.211 cu.in.)
16.6 mm (0.654 in.)
16.0 mm (0.63 in.)
3,000-36,000 r.p.m.
2.0 ps / 30,000 r.p.m.
395 g (13.93 oz.)
■
■
■
■
■
■
UNF1/4-28
30.8
45
87.4
38.5
44
29.5
21
37
4- 3.3
54
SPECIFICATIONS
21VG-PX THREE VIEW DRAWING
Displacement
Bore
Stroke
Practical R.P.M.
Power output
Weight
Dimensions (mm)
48
3.46 cc (0.211 cu.in.)
16.6 mm (0.654 in.)
16.0 mm (0.63 in.)
3,000-36,000 r.p.m.
2.0 ps / 30,000 r.p.m.
433 g (15.27 oz.)
■
■
■
■
■
■
SPECIFICATIONS
21VG-P ES THREE VIEW DRAWING
Displacement
Bore
Stroke
Practical R.P.M.
Power output
Weight
Dimensions (mm)
UNF1/4-28
30.8
45
87.4
21.3
44
29.5
21
37
4- 3.3
54
14.3
C
Copyright 2006 by O.S.Engines Mfg. Co., Ltd. All rights reserved. Printed in Japan.
600 91820 0 608 03
TE L. (06) 6702-0225
FAX. (06)6704-2722
6-15 3-Chome Imagawa Higashisumiyoshi-ku
Osaka 546-0003, Japan
URL : http://www.os-engines.co.jp
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