Century UK BS903T Instruction Manual Download Page 5

ENGINE TUNING GUIDE

RUNNING THE ENGINE

STARTING THE ENGINE
IMPORTANT!

MAIN MIXTURE CONTROL NEEDLE

IDLE STOP SCREW

IDLE STOP 

SCREW

   MAIN MIXTURE

 CONTROL NEEDLE

The main mixture control needle points upwards from the carburettor

 (see image).  It controls the fuel/air mixture supplied to the engine. 

The needle is factory set for runningin, at 4 1/2 turns out (anti-clockwise)

 from its fully closed position. Once run in, the main mixture control 

needle would typically be set2 and 2-1/2 turns out from fully closed. 

You should be aware that the main mixture control needle settings will 

require small adjustment dependingon the temperature, humidity and

even the altitude above sea level. 

The idle stop screw is located towards the rear of the carburettor

(see image). The purpose of this screw is to set the speed at which

the engine idles or “ticks over”. It has no effect on the mixture control

settings of the engine and has been pre-set at the factory to default 

settings. With the air filter removed, you will be able to see the barrel 

inside the carburettor. With the throttle set to idle, the gap visible on the 

barrel should be around 1mm. Any changes to the idle speed of the engine 

will require only very minor adjustment of this screw. We recommend that 

the screw is set to allow the engine to idle at the lowest speed possible. 

Running the engine with an excessively high idle speed could result in the 

centrifugal clutch partially engaging. This could result in premature wear of the brakes or a 

complete failure of the clutch assembly. After making any adjustments replace the air filter

immediately. Never operate the car without the air filter fitted to the carburettor.

1. Fill the fuel tank withfresh model “nitro” fuel containing no more than 20% nitromethane.

2. To prime the engine when cool, place your finger over the tuned pipes exhaust exit and 

    gently pull  the pull start several times. You will notice that fuel will travel through the fuel 

    line towards the carburettor. Be careful not to over-prime. You should stop priming when 

    the fuel reaches the carburettor.

3. Ensure that your glow start (not included) is fully charged and attach to the glow plug 

    situated in the cylinder head of the engine.

4. With the throttle set to idle, start the engine by pulling the recoil starter handle using short, 

quick pulls. Do not pull the recoil starter out to its maximum. If you do, it is most likely that 

you will weaken the pull start return mechanism and it could fail entirely.This will not be 

covered by the warranty on your car.You only need to pull the starter out to a maximum of 

around 20cms or 8”. Sometimes when the engine is already hot, it can be easier to start the 

engine at a higher throttle setting (1/4 to ½throttle). When the engine starts immediately 

return the throttle setting to idle. Failure to do this can cause the engine to over –rev and 

cause serious damage.

The radio system must always be switched on and operational when the engine

 is started. Never switch off the transmitter or receiver with the engine running.

Summary of Contents for BS903T

Page 1: ...ommon with all R C cars stresses and vibrations can cause screws and fastenings to work loose It is your responsibility to carry out regular checks tighten screws where necessary and generally maintain the car to ensure optimum performance and reliability This high performance radio controlled car is not a toy Used incorrectly it is capable of inflicting serious harm to persons or property It is n...

Page 2: ...tripped WARNING Your car is supplied with a mains operated Ni MH battery charger A full charge of the battery pack will take approximately 7hours You may also wish to purchase a Fast charger If so we recommend one of the following Century UK Power Tech chargers Regularly check all screws and fasteners are secure before operating this model We recommended the application of a small amount of thread...

Page 3: ...nsmitter 2 Insert the bind plug into the port on the receiver marked CH3 Figure 2 3 Connect a receiver battery 4 8V DC to the receiver port marked VCC The two LEDs on the receiver will flash rapidly indicating that it has entered the binding mode 4 Press and hold the bind button on the transmitter and simultaneously turn on the power switch Note The bind button is recessed to prevent accidental op...

Page 4: ... trims before driving failure to do so could result in the car not responding to controls as expected Check the power level of your transmitter batteries prior to use Driving with exhausted batteries could lead to a loss of control Keep long hair and loose clothing away from all moving parts of the car Look after the car by keeping it clean and free of dust and dirt ALWAYS Never drive it close to ...

Page 5: ... clutch partially engaging This could result in premature wear of the brakes or a complete failure of the clutch assembly After making any adjustments replace the air filter immediately Never operate the car without the air filter fitted to the carburettor 1 Fill the fuel tank withfresh model nitro fuel containing no more than 20 nitromethane 2 To prime the engine when cool place your finger over ...

Page 6: ...lar operation 5 Do not accelerate or decelerate quickly 6 The break in procedure can put excessive strain on the glow plug It is recommended you keep a few spares on hand 7 DO NOT allow the engine to overheat The main mixture control needle should be set at a very rich setting This will allow the fuel to carry lots of oil to the internal parts of the engine during the break in procedure 1 Open the...

Page 7: ...ature Never attempt to tune a cold engine Never store the car with fuel left in the tank We recommend that after the final run of the day you empty the fuel tank and run the engine at idle until it stops Then remove the air filter and glow plug from the engine Place two drops of after run engine oil into the carburettor and the cylinder Then pull the recoil starter several times to circulate the o...

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