I got a new airplane for christmas with a brand new OS 46 engine. I have flown it about 20 times but now the engine has seemed to of lost power. it takes for ever to get of the ground and does'nt loop properlly.

Any help will be greatly appreciated.

Treacle

Check the compression, close the throttle all the way and turn the prop by hand and make sure you have good compression. Also check the carbueurator and make sure that it's tight. If all that checks ok then make sure you're not running the engine too rich, that will keep it from running at full rpm. If you haven't got one yet, a small handheld tachometer is a good investment to help you tune your motors.

I just checked the compression and that seemed to be ok and the carbaretor was on tight.

Hi Treacle
Don't know how used you are to setting up engines, but maybe you are running it too rich - although it could be a number of other things, too. Easiest way is to get someone experienced at the flying field to show you how to 'twiddle' the top and bottom end knobs/screws. If that doesn't solve it, then whoever's helping ought to be able to see what else might be wrong.

ps If it is a new engine, you did follow the maker's instructions about running it in, didn't you?

Good luck.

Check to see if your glow plug has the ring seal that came with the glowplug

Hi!
Seems to me that you run the engine too lean! You know how to set the engine , do you?

Treacle, Engines Need to Be Adjusted When The Seasons Change Or When You Change Fule Brands.First Try Resetting The High Speed Needle First.A worn Prop Can Be A Problem.Just Hitting The Ground Ounce Can Cause Problems.
Avistar 2 Also Made A Good Sugestion.When In Dought Change The Plug.Metal From Brake In Can Fowl The Plug But Still Start The Engine.
A Small Air Leak In The Fuel Line (Bubles In The Line To the Carb) Will Stall the Engine But Should Be Checked.
Good Luck And Start Simple Then Try The Harder Things To Fix The Engine

I'd recommend that you read through Frank Granelli's excellent article "Engines 101 - Part Two" about setting up and tuning .40-sized 2-stroke engines at the AMA's Sport Aviator web site:

http://www.masportaviator.com/ah.asp?CatID=8&ID=47

This information should help you check your engine setup and needle settings to help with tuning. Finding a fellow glow flyer who's good with engines would be even better. Good luck and feel free to post any additional questions as they come up.

I have had a few OS engines that a couple of the screws holding on the back plate have come loose. Check these.

Cheers

Wow, nice article, but whoever did the technical review missed a minor slip through that's actually pretty significant. Near the end it says "After about 10 flights for ABC engines, 20 flights for ringed engines, the high-speed mixture can be leaned to 500 rpm less than peak. Never run leaner than this." The word I maked with bold should be richend, not leaned.

I also wasn't crazy that he covered setting the low speed needle before he ever got around to talking about the high speed needle. Typically, the low speed needle is pretty close to the factory, but if it's not, the high speed needle should always be set before any changes to the low speed settings.

Anyway, here's how I set my high speed needle.

Tuning – High speed needle
The following method is designed for sport flying where one wants reliable engine performance (minimum deadsticks) and long engine life (part of which comes from avoiding lean runs).

I’ll start off with a reminder that all needle adjustments should be done from behind the engine and that the plane should be firmly anchored or held. Never attempt to adjust the needle while holding the plane in the air. A small engine blip or wind gust could result in fingers in the prop.

Begin by gradually leaning the engine until you find the peak RPM. Once you find this, turn it several clicks rich. Once you’ve found this slightly rich setting, with a firm two handed grip on the plane, point the nose straight up. While you are doing this, remember to keep the propeller arc out of anyone’s face. When you raise the plane’s nose, one of three things will happen to the engine RPMs.

If the engine speeds up slightly and holds that speed for 10 to 15 seconds, pat yourself on the back (after you put the plane down), you’ve got the needle set pretty well.

If the engine slows down, or does not speed up a bit, it’s too lean. Lower it immediately, turn it a few clicks richer and try again.

If the engine speeds up significantly, it could probably be a bit leaner. Put it back down, set it a bit richer and try again.

That’s it, no magic…

Chuck, If you notice in the paragragh preceeding the one You quoted, Granelli had the engine running 1000 rpm less than peak. further richening would cause the engine to run more than 1000 less than peak, As he already had the engine running rich you would have to LEAN it to get it closer to peak.

Some one told me at club that they would try flating the glowplug washer to get more compression

OK, I missed that part. Since many people don't have a tach, I still think it's better to learn to set the needle by sound and pointing the nose in the air, than purely based on RPMs. This method helps confirm that the engine will not lean out and die during a steep climb, during takeoff for example.

the most basic thing I did after about 15 flts on the NEXTAR OS 46fxi was change my glow plug and check all the bolts on the engine after I noticed that my power was going down the tubes all of the head bolts had loosened up just a bit after tightening them and a new plug it has run fine, later I did lean out the low end just a bit but not much was needed.