When changing fuel or when the weather changes, you may need to retune your engine. This chart indicates you what to do according to the changing weather conditions and fuel. Take your time when tuning your engine. Only make 1/16 turn at the time and let the engine warm up before you try to tune your engine. Adjust the high speed needle first and the low speed needle last. Never tune your engine for a specific temperature. First, tune your engine by the amount of smoke, sound, feel and performance. Then, check the temperature just to make sure the temperature is not too high. An engine can perform well at 200F one day and can perform well at 240F another day. This list is to help you when you change fuel or when the weather changes. To tune your engine, always refer to the instruction manual. Since fuel manufacturers don’t use the same quality of lubricant, it is important to pay close attention to the performances of your engine when you change brand of fuel. Remember, it is always safe for your engine to be on the rich side.Print this page and keep a copy in your toolbox.
| Conditions | What you should do | |
| Higher nitro content | Rich |  |
| Lower nitro content | Lean |  |
| Hotter glow plug | Rich | |
| Colder glow plug | Lean | |
| Higher oil content | Rich | |
| Lower oil content | Lean | |
| Higher air temperature | Lean |
|
| Lower air temperature | Rich | |
| Higher altitude | Lean | |
| Lower altitude | Rich | |
| Higher humidity | Lean | |
| Lower humidity | Rich | |
| Higher barometric pressure | Rich | |
| Lower barometric pressure | Lean | |
