correct engine settings

If you have followed our steps for engine building you also already adjusted the engine to race setting.
In case you like to adjust your engine to optimal settings or lost your setting due to maintenance this is the route you can follow.

The pictures below explains the needles you usually find on model car carburators.
We try to bring you for each brand a separate picture.

	NOVA ROSSI-REX-TOP-R&B 2 needle versions
	SIRIO 2 needle versions
	CMB flatslide type I and II 2 needle versions
	CMB R4 3 needle version

How to adjust your engine in correct order?

First close the HIGH SPEED needle and then open it 3 full turns anti clockwise.
This will do generally for all brands of engines.
Press the engine against the starter wheel and choke the engine by closing the exhaust for about 4 seconds.
This is to assure that the empty fuel line is filled with fuel.
Now connect the glow-plug igniter and start the engine without opening the throttle.
If the engine does not start, turn the stationary (IDLE SPEED) screw by 1/8 turn steps clock-wise until the engine fires up.
Now if the engine is running at stationary IDLE SPEED speed OK, check if oil splashes and smoke are coming from the exhaust.
If not! Open the LOW SPEED needle by a 1/4 turn couter clockwise until it does.
If it is running richer (the engine stalls with a rumbling sound) turn the IDLE SPEED screw clock-wise until the engine runs stationary (idles) OK.
Again check if oil splashes and smoke are coming from the muffler. Do not touch the HIGH SPEED needle yet!
Now, let the engine warm up first to about running temperature of 90 degrees Celsius.

HIGH SPEED
Try to run the engine at average speed on the track. We are not yet looking for the clean rev up of the engine we only like to adjust the HIGH SPEED.
So it might be that the engine is going from idle to full speed with a 4-stroke rumbling sound, we take care of that later!
If the engine is not running rich (4-stroke), no smoke and no rumbling sound, open the HIGH SPEED needle again by 1/2 turn steps counter-clock-wise until it does.
In all cases smoke should leave the muffler when the throttle is opened fully.
Now close the HIGH SPEED needle in 1/8 turns steps clock wise between each lap until it sounds right at speed and still smoke is leaving the muffler.

LOW SPEED
If the engine is running stationary (idle) for 5 seconds and the throttle is opened fully the engine should pick up rpm's without any rumble or hick up.
If it tends to rumble close the LOW SPEED screw by 1/8 turns steps clock-wise until it picks-up OK.
If it tends to hick up (grasping for air) then open the LOW SPEED speed needle by 1/4 turns steps anti clock-wise until it rumbles again.
Then close the LOW SPEED needle by 1/8 turns steps clock-wise until it picks up rpm's OK..
Still check for the oil splashes and smoke from the exhaust. Keep checking the temperature of the engine and smoke trails coming from the muffler.

LOW SPEED PINCH TEST
To be sure if your LOW SPEED setting is inside 90% zone you can use the pinch test.
Clean the engine with 2 second full throttle at let it idle.
Pinch the fuel line at 2 cm from the high speed needle.
If the engine stops without revving up your setting is to lean.
Open the LOW SPEED needle by turning it 1/8 turn counter clock-wise.
If the engine stops with revving up high. your setting is to rich.
Close the LOW SPEED needle by turning it 1/8 turn clock-wise.
If the engine stops with just a little higher revving your almost near perfect LOW SPEED needle setting.

IDLE SPEED
When adjusting the LOW SPEED needle it might be needed to change the idle speed too as the LOW SPEED is of influence of the IDLE SPEED needle.

!IMPORTANT!
After setting HIGH SPEED - LOW SPEED - IDLE SPEED in this order recheck the HIGH SPEED by turning the HIGH SPEED needle 1/2 turn counter clockwise.
Now close the HIGH SPEED needle in 1/8 turns steps clock wise between each lap until it sounds right at speed and still smoke is leaving the muffler.

MEDIUM SPEED
Only some carburators are equipped with this third MEDIUM SPEED needle screw. From factory setting use this screw to set the transition from low to high speed.
The medium speed screw works in conjunction with the LOW SPEED. If you turn the LOW SPEED screw for example 1/2 turn clockwise you have to turn the MEDIUM SPEED needle a 1/2 turn anti-clockwise.
In case you are not experienced enough with tuning leave the screw at factory setting.

If you have lost the setting on a carburator with 3 needles this is general way to get close to the factory setting.
1] Remove the HIGH SPEED needle assembly
2] Set MEDIUM SPEED speed needle flush with the carburator body
3] Looking at the MEDIUM SPEED needle THROUGH the hole in the carburator body where you've removed the HIGH SPEED needle assembly, adjust the LOW SPEED needle (plus or minus) until the hole in the side of the MEDIUM SPEED needle is lined up directly with the HIGH SPEED assembly hole. Don't touch this needle again if your are not farmiliar with its tuning..
4] Reassemble HIGH SPEED needle assembly and thread it back in carefully.

TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS TIPS

TIP 1 ! The break-in period is 80% the key for a good running engine and a long lifetime. Try to stay below all maximum settings of the engine performance. If you are just running your car for fun, then be sure that the engine is running always at a richer setting.
Try to warm up the engine for 2 minutes minimum by running the car at medium speed (rpm's) before asking the maximum power from your engine.

TIP 2 ! When your engine was running fine before and it does not want to start, then this is the golden rule. Open the throttle fully.
Start the engine without connecting a glowplug igniter for 3 seconds. Lift the car and then close the throttle. Now put the glow igniter on and the engine should start, easily. If not check for fuel, defective glow-plug or whatever. But do not touch the needles. Only minor changes (all within a 1/2 turn) could be needed if the external circumstances are changed. A good running engine, does not need frequent needle changing.

TIP 3 ! Always check the engine temperature frequently, by putting some spit on your finger and then on the cooling head. If it does not evaporate the engine temperature is around or below 100 °C. You may close the high speed needle a little if required. If it stays for 3 to 4 seconds the temperature is OK. If it evaporate direct, then open the high speed needle until the temperature goes down.
An engine temperature system is a nice feature and can prevent premature engine failure due to overheating.

TIP 4 ! After using your engine these are the things to do:
Remove all fuel in the engine and carburator by taking off the fuel line and let the engine run until it stops. Then put some after run oil in the engine and run the motor for 3 seconds on the starter box so the oil is spread inside the engine well. This will prevent rust building up inside the engine if not used for a long period.