How To:  Tuning an Engine

  This article is written for newbies and anyone who is unfamiliar to tuning an engine. First Lets take a look at what type of Carberator you have. Find which type you have from the diagrams below:

If your carb looks like diagram #1 than you have what is called a "Twin Needle Carb" (I call them TN Carbs). If you have what is in diagram #2 than you have a "Air-Bleed Carb" (I call them AB Carbs). Now that we know what you got lets tune this engine!

First off, make sure you've mounted the proper propeller, Refer to your engine's instructions. Also make the propeller is FIRMLY attached! Next be sure your glow plug is good. To test remove it from your engine and put it on your Ni-Starter, and see if it glows. It should glow a deep yellow-orange color NOT white!  Now screw it back into your engine. Now fill your fuel tank with fresh fuel, with the proper amount of oil-content and nitro (if you are not sure, refer to the instructions). Now open the throttle all the way and place your thumb over the carb's throat and turn the propeller over (without the ni-starter on!) with your other hand until you see fuel in the fuel line flowing it into the carb, now turn it over 2 more times and put the throttle to idle. But the ni-starter on and flip the propeller swiftly to the left (counterclockwise) until the engine starts. Or use a electric starter.

   Once you get your engine is running, move to behind the propeller and hang firmly onto the plane. Let the engine run for about 15 seconds and then carefully remove the ni-starter.

              TUNING

#1 High-end Mixture setting

To set the high end, slowly advace the throttle to full. Now the engine should be running very rough and spitting out raw fuel out the muffler. Now turn the Needle-valve (the big one on the left side of the carb) in (counter clockwise) until maximum RPM is heard, now back the needle out 4 clicks. The high end is now set. To check it hold the nose up about 30 degrees and listen the RPM should increase slightly. Keep it up for about 20 seconds. If it suddenly dies the mixture is too lean and the needle needs to be richened (clockwise) afew clicks. Do this over and keep adjusting intill it is right.

#2 Idle Mixture

Next comes the idle mixture. Put the engine to idle.
Now pinch the fuel line (going to carb) with a pair of needle nose pliers, and listen. The engine should speed up slightly and then die. If it is speeds up excessivly the mixture is too rich and the idle screw needs to be turned in (out on AB carbs). If it doesn't speed up at all, the mixture is too lean and the screw need to be turned out (in on AB carbs). Repeat until it is right. This is just roughly tuning the idle fine tuning is next.

#3 Transition (Idle fine tune)

Now that we have the idle roughly tuned we can now fine tune it so we have a smooth transition to full power. Let the engine idle for 20 seconds then swiftly advance the throttle to full power. If the engine spits and sputters, and slowly advances to full the idle mixture is too rich, and needs too be leaned out (tuning #2). If it hesitates (not sputter) or misfires than the the idle mixture is too lean and needs to be richened. The transition should be quick and smooth.

You now have a fine tuned engine, so go fly!

-Darrell Nutt