Nitro Engines
The above URL will help answer some of the questions we’ve all had at one time or another, such as:
- How does a glow engine work?
- How to tune a glow engine.
- How to Break in a new engine.
- When does an engine need to be rebuilt or replaced?
From the page:
How do I know how to set the air bleed screw on my engine?
Always follow the printed instructions for your engine. As a general guideline: As the air bleed screw won’t affect the way the engine runs with the throttle barrel more than a couple of mm open my suggestion, turn the screw all the way in until it stops (DON’T over-tighten it). This will give you your maximum rich idle mixture. Now set your high-speed needle as instructed in your manual.
You can then back out the screw a little at a time. In order to see if you have too rich or too lean an idle mixture, pinch the fuel line closed with the engine idling. If it speeds up noticeably immediately, then the mixture is too rich and you need to back the screw out some more. If the engine dies immediately, the mixture is too lean. If it idles steadily for a few seconds, then speeds up, then dies, it is just right. Between each adjustment run the engine at a high throttle setting for 15-20 seconds or so to clear out any excess fuel which will make it harder to determine the correct needle setting.
(Remember that the high and low needles affect one another so you will need to work back and forth between them to get a perfect running engine.)
Someone told me to use the idle needle to set the midrange on my 2 stroke engine. Someone else told me that the high end needle sets mid range. What’s right?
With most 2-stroke engines, you don’t set mid-range by using the idle mixture adjustment. The idle mixture adjustment is for idle only. As with most engines, it’s not easy to break it in and find initial settings by flying the engine in the heli. It should have some test-stand time with an airplane propeller.)
Here’s the correct way to set the carburetor:
- Make sure idle mixture is set excessively rich.
- Start engine and get it to full throttle.
- Adjust engine so that it’s running properly at full throttle…this means that it will be leaned to just below peak RPM. This setting keeps your engine just rich enough so that you won’t go lean of peak when the tank gets low.
- Retard the throttle and adjust the engine until you have a proper idle setting. The idle setting should also allow a reasonable acceleration.
- You then must accept what you get for the midrange. If the high and low end needles are properly adjusted, and you are utilizing an appropriate plug, propellor and fuel, and your engine is operating properly, you should have an acceptable mid range at this point. You may need to adjust high or low slightly to a compromise for a mid-range you are pleased with.
You will not get the needle valve set correctly unless the engine is run at full throttle. You cannot use the idle mixture adjustment to help with the midrange. We’ve found that once the high-speed needle’s been properly-leaned, and the idle mixture set, most 2 strokes now have a good midrange.
A lot more useful information and reference material………
Thank you to OS Engines
Regards
CFI
Saito Glow Engine Tuning Tips
Some helpful information from the manufacturer to gain the best performance and engine longevity from their product range … and hey, might even minimise dead-stick landings.
Please do not hesitate to discuss any of this content or request a demonstration.
Thank you to Saito Engines for the information provided
SPECIAL NOTE …
Your attention is directed to item #5: NOW DON’T MESS WITH IT ANY MORE!
Regards
CFI
Useful Links
| Link | Description |
|---|---|
| How to Balance a Propellor | A video tutorial on prop balancing. The presenter uses a Dubro balancer but the principles can be applied to any balancer. |