All nitro RCs need to have their electronics set up properly before operation. On a nitro RC, the electronics control both the steering and the throttle. If either system is not properly configured, the vehicle might not steer or accelerate properly. You could potentially damage the servos, crash the vehicle, and even hurt yourself or someone else if you try to drive a nitro RC without confirming the electronics are set up properly.
This is important
Seriously, take the time to understand how the steering and throttle control systems on your vehicle work and how they can be configured. It is very common for owners to just start the engine and try to drive their nitro RC without any inspection of the electronics. Don’t be that kind of owner! The manual for your nitro RC model has all the information you need to set up the electronics.
Even if you bought a brand new nitro RC, you should still check the electronics to confirm that all systems are working properly. If you bought a used nitro RC, you’ll likely need to tweak the electronics.
Setting up the electronics
Refer to your manual for detailed, model-specific information, but in general here is what you need to do.
NOTE: Perform set up with the engine off.
Confirm transmitter and receiver are bound
Turn on the transmitter, then turn on the receiver. Confirm that the transmitter and receiver are bound by turning the steering wheel and pulling the throttle trigger. Confirm that turning the steering wheel left actually turns the wheels left and vice versa. Also, remove the air filter from the carburetor and confirm that pulling the throttle trigger opens the slide in the carburetor and that the slide closes when you return the trigger to neutral.
If you have any problems with the transmitter not controlling the steering or throttle, go through the binding process in your manual.
Reset the transmitter settings
This will depend on your transmitter, but generally all transmitters have settings for Steering Trim, Throttle Trim, and Dual Rate. Steering and Throttle Trim are almost always accessible through physical knobs, while Dual Rate might need to be changed through a screen on the transmitter or through an app (refer to your manual). Regardless, make sure each setting is reset to zero.
Reset the servos
Turn on the transmitter then receiver so the servos reset to their neutral position, then turn everything off.
Confirm the front wheels are pointing straight ahead in a neutral position. If not, remove the horn from the steering servo and reset its position so the wheels are pointing straight ahead.
With the air filter removed from the carburetor, confirm the slide is in the idle position (0.5-1mm gap or whatever is recommended in the manual). Adjust the horn on the throttle servo or the throttle linkage as necessary to get the slide close to the idle position. You don’t need to get it perfect, just close so you can adjust it to perfect later with the throttle trim.
Set the throttle trim
Turn the transmitter on and then the receiver. While looking at the slide in the carburetor, apply the brakes and see if the slide closes further. If it does, adjust the throttle trim to close the slide until it won’t close any further when the brakes are applied.
You don’t want the carb slide to close any further when you apply the brakes. If the carb slide closes further when you apply the brakes, your nitro RC will likely shut off every time you apply the brakes. This is a common issue with owners that haven’t set up their throttle properly.
Set throttle endpoints
The endpoints control how far the servo will turn when applying full brakes or full throttle. Figure out how to adjust the endpoints on your transmitter, then apply full brakes and full throttle to see where the end points are currently set.
For the brakes, you want the drivetrain to lock up when you apply the brakes. Roll the car on the ground and apply full brakes. If the car doesn’t stop quickly, adjust the end point. If the endpoint adjustment is maxed out and the car still isn’t stopping, you’ll need to adjust the brake/throttle linkage.
For the throttle, you want the throttle to completely open when you apply full throttle, but not anymore than necessary. Remove the air filter and apply full throttle. If the slide doesn’t open all the way, increase the end point. If it’s opening too much, decrease the end point. Having the endpoints at the extreme ranges can damage the servo, so only increase them as much as needed.
This video by Invisible Speed RC talks through the general idea of setting up your throttle linkage and endpoints. The actual set up will be different on your nitro RC, but this gives you an idea of what you’re trying to accomplish.
Set the steering endpoints
You want the steering endpoints to only turn the wheels as much as the steering geometry allows. The steering servo can be damaged if the endpoints are set so that the servo is trying to turn the wheels further than the geometry allows.
To test, turn the wheels all the way to the left or right with the transmitter and while holding that position, adjust the endpoint. Stop when the wheels won’t turn anymore and then back off a touch so there is no stress on the servo. Complete for both left and right.
Confirm fail safe is operating
Every modern nitro RC receiver has a fail safe built into it. This feature will return the servos to neutral (or sometimes apply full brake to the throttle servo) if connection with the transmitter is interrupted or lost. This is a safety feature that you want to make sure is working. The manual for your nitro RC model or receiver will have instructions on how to test the fail safe feature. In general, it’s just a matter of turning on the transmitter, then the receiver, and then turning off the transmitter. The throttle servo should return to the neutral or full brake position. If it doesn’t, go through the fail safe set up outlined in your manual.
Throttle Return
There is one additional safety feature that your nitro RC should be equipped with: a throttle return. This is a mechanical fail safe that applies tension to the throttle linkage so that if your electronics fail completely, the throttle will be closed mechanically (e.g. if your receiver batteries die or your throttle servo strips a gear). Most modern nitro RCs come with a throttle return spring, which is a metal spring that is attached to the carburetor and the throttle linkage. You can also use multiple rubber bands to create a throttle return.
Test the throttle return spring by applying full throttle on the transmitter and while holding that position, turn off the receiver. The spring or rubber bands should return the throttle to the idle position.
You’re done!
It seems complicated, but it will all make sense once you do it once and see how everything works. Below is another video I suggest watching that will help make sense of all this set up info.