Tuning your Nitro RC Car, the simple guide...

You bough a new car, you've done the breaking in with your carb at factory settings, now what? Follow this simple guide and get your nitro engine tuned up in a breeze.

Image for illustration purposes only, positioning of the needles may vary with different engines.

Please adjust the needles following the steps order.

Step 1:

How to adjust the High Speed Needle (HSN)

1. Start your nitro engine, put the car on a stand
2. Accelerate in short bursts
3. Does the engine stall when you remove your glow starter?

Yes = Lean the mix by screwing IN the HSN 1/4 of a turn, then go back to step 1.

No = Go to step 4

4. Put the car on the ground and accelerate all the way for 2/3 seconds, pay attention at how does the engine sound
5. Lean the mix by screwing IN the HSN 1/4 of a turn
6. Repeat step 4
7. When comparing step 6 to step 4, does the engine struggle to reach higher revs or does it even stall at full speed?

Yes = Make the mix richer by un-screwing the HSN 1/4 of a turn, that's it the HSN is set!

No = Go back to step 5 until the answer is Yes, then do the above.

Step 2:

How to adjust the Idle Speed (Mechanical Minimum):

Once you've completed step 1, you can move on to adjusting the idle speed screw.

1. With the car on a stand, let the engine idle for around 10 seconds
2. Does the engine stall?

Yes = Tighten the idle speed screw 1/4 of a turn and go back to step 1.

No, but the idle speed very high and the wheels are starting to spin... If so, loosen the idle speed screw 1/4 of a turn and go back to step 1.

Once your car idles and the wheel are not spinning then the idle speed is set correctly.

Step 3:

How to adjust the Low Speed Needle (LSN) - Method 1

1. Put the car on the ground and accelerate all the way for 2/3 secs.
2. Let the car idle for around 10 secs.
3. Does the nitro engine struggle to loose revs or does it even rev up?

Yes = Make the mix richer by un-screwing the LSN screw 1/4 of a turn and go back to step 1.

No, the engine revs down correctly but it ends up stalling... If so, lean the mix by tightening the LSN 1/4 of a turn and go back to step 1.

No = The engine revs down correctly and it idles fine... Great! You have set the LSN!

How to adjust the Low Speed Needle (LSN) - Method 2

1. Warm up the engine to operating temperature.
2. Put your RC car on to a stand and let it idle.
3. Once idling, pinch the fuel line to cut off fuel supply to the carb.
4. Does the engine rev up for a couple of seconds and then stall?

No, the engine stalls pretty much instantly... If so, make the mix richer by un-screwing the LSN screw 1/4 of a turn and go back to step 1.

No, the engine takes 5 seconds or more before stalling... If so, lean the mix by tightening the LSN 1/4 of a turn and go back to step 1.

Yes = The engine revs up for about 2 secs and then dies. Congratulations, you have tuned the LSN!

In most cases, your nitro engine tuning ends here. Some carbs will have a 4th needle, if your engine has one, please go to the next step.

Step 4:

How to adjust the Medium Speed Needle (MSN) (only present on selected nitro engines)

1. Put the car on the ground and GENTLY take the car to top speed.
2. Is the transition between low revs and high revs very quick? Does it feel like the car is skipping the medium revs altogether?

Yes = Make the mix richer by un-screwing the MSN screw 1/4 of a turn and go back to step 1.

No, but the transition between low revs and high revs is very slow or even sluggish... If so, lean the mix by tightening the MSN 1/4 of a turn and go back to step 1.

No = I can hear the mid revs kicking in and the car accelerates just fine.

CONGRATULATIONS! YOUR NITRO RC ENGINE IS NOW TUNED!