Friday, December 25, 2099

Tuning the needles to keep the car running

Seen here is the high speed needle, and the idle needle. The high speed is the one with the golden thing around it, and the idle is the little black one under the air filter. The first one you may need to adjust is the idle needle. Remove the air filter and take a look into the carb. You should see a hole that is very tiny, like only 1mm or so. Engage the brakes with the transmitter, and make sure the hole does not close up completely. If it does, adjust the idle needle. Turn it clockwise to make the carb hole open and turn it counterclockwise to make the carb hole close.

Here you can see the low speed needle screw. It is the one in the middle of the rubber just under the bar on the top. For factory settings, it is recommended to turn the high and low speed needles all the way in (until they dont turn easily anymore) and then turn them 2 and a half turns counterclockwise. Keep them at this for breaking in.


  • Engine turns on, but the wheels go automatically and the car won't stay still
    • This is because the idle is set too high. To fix, turn the idle to the left a little and try again. You can also try turning the "throttle trim" dial on the transmitter to close the gap a little.
  • Engine turns on, but turns off quickly
    • This is because the idle is set too low. Do the opposite of what you did to fix the first problem.
  • Engine won't start
    • There are a number of things that could be the problem for this. First check to see if the glow plug is glowing. Remove it from the car and while holding it on the sides, push it into the igniter. If it glows orange, than its good. If it doesn't glow or is very weak, check to see if the igniter is charged, then replace the glow plug itself if that doesn't work. Also, make sure there is fuel in the lines, and make sure the idle isn't too low.
  • Engine cuts out when brakes are applied
    • Usually if this happens, you need to adjust either the idle or low speed needle.


  1. nice and informative post and i would like to add few words about nitro R/C car's engine.
    Nitro R/C cars can be huge fun but for that to be the case there is one thing that you need to get right and that is the tuning of the engine – or more correctly getting the carburettor settings right. If you do not, then you are just going to get endless frustration.
    it is easiest to have a temp gun you can get one at any local hardware stores. first thing to do is locate all of your needles on your carburetor the main needle or high end needle is typically the needle located right where your fuel line enters your carburetor because it is the MAIN needle it controls the fuel flow next to be located it your low end needle usually found on the slide of the carburetor. see further informations at nitrotek.

  2. Great info for a nitro newbie!

  3. What should you do if your throttle stays wide open every time I start it just starting break in mode and these directions are horrible

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  5. Why do I have nitro coming out from glow plug I never noticed this till now ran it last night just fine than today will start than dye right away. Please help

  6. Hi I am new to this hobby but have loved nitro cars for a long time. I've already did the break in on the engine which is letting it idle on 4 tanks of fuel. I ran it rich with 2 tanks of fuel on half throttle. Now I want to tune the car to perform better but cannot seem to get it right no matter what I do. It's burning very rich and spits out fuel from the muffler outlet. Please help me with info on what I can do. A tank of fuel is not even giving me 2 minutes of play time. The car is a nitro rs4 3 evo+.

  7. Thanks for the tips im wating for my Exceed 1/10 hyper speed buggy in the mail

  8. Thanks for the tips im wating for my Exceed 1/10 hyper speed buggy in the mail

  9. Hello all is there anyone who knows the correct setting for the 18cvx engine please.. like high speed and low speed n idle.. I forgot to prime it and kept trying to start it n then saw the was no fuel go in and by then I had messed the settings totally.. thank you

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  11. I'm just wondering in anyone can tell me the difference between nitro n electric n if electric overpowers nitro...! Also I'm wondering which got more power between 18cvx n 2.5 force. I'm assuming 2.5 is 25 engine which makes bit more powerful but not sure. Can one answer best way to get best if newbie n if all nitro have diff oil which is best!