Can anyone tell me what the base-line setting for the air bleed screw on an OS LA 46 is? One of the local "experts" told me you opened it up inserted a straight pin, then turned the air bleed screw in until it contacted the straight pin. It seemed a little arbitrary to me, but he has 27 years experience and I'm working on week 2.

Now when we fly the plane (Eagle II) it still seems to sag, in what I'm told is a lean condition about halfway through a tank of fuel, even with what I think is a way too rich needle-valve setting. I've got about 8 flights on the engine, plus a couple of tanks run through on the ground, so I'm assuming the engine should be getting towards being broken in.

My theory is that at hight throttle settings, the engine could be pulling enough air through the bleed hole to mess with the needle jet settings. My plane comes down after a fight looking like it flew through an airborne oil slick. Other planes at the field running the same fuel seem to be wearing much less spooge.

There are a couple of LT-40's at our field, one with a TT Pro 40 , and one with a TT Pro 46, and they just sing! My engine will hardly pull me over the top of a loop! Both LT-40's spank my plane going straight and level. Yesterday I had to fly full throttle just doing circuits and figure 8's. (Ad nauseum as per instructor!)

I want to get back to base-line settings and tune it as per the owner's manual and see if I can get it sorted out.

Also, right now I have a 10x6 prop on the engine, that's what was on it where I got it so I have not changed anything. I've noticed that the manual recommends 11" props for this engine. Should I change the prop? Being an utter newbie I imagine that using a shorter prop will give me an extra bit of margin for error on landings (hopefully will get to try a few today!) but a longer prop would move more air right?

I have just put a brand new fuel tank in the plane and am running XP Sport fuel with 10% nitro.

Cool hobby! Much less expensive than dirt-bikes and I haven't needed a ride home in an ambulance yet....SWEET!

Thanks in advance!

okay, tune the high speed needle valve first. Set it to maximum RPM and them back it off a few clicks untill the engine starts to slow down just a tiny bit. Then pinch the fuel line going to the carb to test it. Only pinch it for a slit second. Just put your thumb and forefinger on the line and pinch it rather quickly for about a half second. When you pinch the fuel line, the engine should revv up just a bit. When you let go of the fuel line, the engine should continue to run, just slightly rich still.

Now for the airbleed. Throttle down to a decent idle. I dunno- maybe 2200RPM or 2500RPM. Whatever feels nice, and won't make the plane creep down the runway when your sitting and idleing.

Let the plane idle for about 20 seconds. Then quickly advance the throttle to full. The engine should pick up and run smoothly at full throttle. If it starts coughing and sputtering before it revvs up, then your too RICH on the low end. If it dies before it gets fully revved up, then your too LEAN on the low end.

To adjust for a RICH engine, turn the screw OUT about 1/4 turn at a time. That allows more air to get sucked in, which in turn leans it out a bit.

To adjust for a lean engine, turn the screw IN about 1/4 turn at a time.

As far as the engine sucking air through the airbleed hole at full throttle-- thats not happening. When the throttle barrel is fully open, the airbleed hole is blocked off. The airbleed hole only gets exposed when your about 1/4 throttle and below.

Look down the barrel of the carb with a flashlight when its NOT running. Move the throttle slowly up to full and then down to idle. You can see when the airbleed hole bocomes opn and when the barrel slides past it and closes the hole.

Have fun.

Well for one thing a TTpro46 outperforms the OS46La hands down. If you have lost your basline and do not want to read the manual, I will summarize for you.
* If you are totally lost in your settings and want to go back to square one. Do this. Open your high end 3 turns or whatever. Now look into the carb and open the barrel to its approximate idle position which is not much.
*Now take your fuel line off the carb and put on a separate line long enough for you to blow into. Close your low end screw. Now at the same time, blow into the tube and open your low end until you hear a hissing. Congratulations- Your low end baseline is set.
*Hook it all back up to normal start it up and tune it as best you can. Once done, lets double check.

1 tune high end first, this is for the most part a no brainer. Start with the needlevalve open 2-3 turns. Screw it in until the rpm reachs that point from rich to lean. Some people use pinch methods to check high end. Some like a slight increase in rpm when the line is pinched. I go for no change.
2. To check your low end, disconnect the fuel line while the engine is running. If the rpm increase before the engine quits, your low end is to rich therefore close the nedle a bit (1/16-1/8 turn). If your rpm just goes down and engine quits, your low end is too lean-open a tad.

There are alot of double checks to make and engine run perfect and mine do.

Cyclic Hardover...that's good advice for setting the idle mix on a twin needle carb but the OS 46LA in question has an airbleed carb. The advice given by Rcpilet is more suitable for his engine.

Hi David and welcome to the hobby. I thought I would elaborate on the reason a TT46 will out perform an OS 46 LA is because the LA has brass bushings to support the crankshaft where as the 46 pro has ball bearings. Also the carbs are different yours being of the air bleed type, The pro 46 having a low end adjustment as well as the high end adjustment, seems to help with transition. I'm not by any means an engine guru so maybe someone can explain a little better.

I set mine the same as Rcpilet
Have a goodun,John.

Hmm...methinks this engine will suffice for a short while, but is going to get replaced in the not-to-distant future. There is a field closer to my home that I will be doing alot of flying at that is shorter than the club field I've been learning on and I would like more power so as to shorten up takeoff runs.

What should I get OS FX 46? (will the exisiting holes in the engine mount work with the FX engine?)

TT 46 Pro??

Any others?

I would probably want something that I could move to a second aircraft down the road and put the LA back in the Eagle II for my kids.

Hopefully the second plane will help me explore aerobatics a bit so that will be a consideration when getting another engine.

Then you definitely want to go with a 46 that has ball bearings, like the OS46FX, or the TT. Personally, I like Os and have never used the TT, but I have heard that the TT is almost as good as the OS, and considerably easier on the wallet.

Some of our members are flying the LA40 with FX 46 OS and FX61 OS , the tt cost less than OS but the OS scoots the plane along a tad faster,I like the 61 FX better, especially as you progress in learning. Just my .02.
Have a goodun,John.

In my neck of the woods I think there is only about $30 difference between the OS FX and the TT Pro.