I have a OS40LA on a Hobbico Superstar and am wondering if anyone as found the best fuel% and prop combo for this underpowered engine. im running 15% and a 10x6 prop. and the plane flys abit slow for my liking... can aford a new engine right now. accepting donations of anything unwanted

if you want it to go faster a 9x8 may work

10x6 or 9x7 and 10% fuel. Your not gonna get anymore out of it unless you put it on a lighter plane, it was never meant to be a powerhouse. A viper would be a fun entry into quickys, it woulsn't be slow, not a rocket ship either but would move along ok for a third plane anyway.

A moose can mufler might be a kick in the pants

Yea, you're just not going to get much punch from a 40LA. The best thing you can do is start saving your pennies and get an inexpensive 46 ball bearing engine.

Maybe it's me but I've always run 10X7 or even 11X7s on my LAs. 10s for the .40 and 11 for the .46. Ilike these engines because they're light. That means Ican put them in smaller airframes and pull the plane around with a 10 inch prop where the designed ball-bearinged engine would only spin a 9X6 or something like that. I'm thinking like the Great Planes .25 T-craft or the Thunder Tigre Lazy Tiger Mustang that Icurrently have a .46LA on the front. It spins a 10X7 4-blade APC prop quite well. Ilove these little "underpowered" engines!

Nope, those are about the normal sizes that most people run on these engines but when looking to make a plane fly the way you the pilot would like it to you have to start testing different sizes and spending a lot of time doing it.
As Minn mentioned though, you can only do so much before you need to buy something with a bit more punch.
Iused almost nothing but the LA .46 engines on my 40 size fun fly planes and loved them but there are better choices when looking for more power. Just takes more money though and right now I can understand that little problem.

You can take the baffle out of the stock muffler and gain a little horse power. The noise level go up as well. Do you fly out at Fentress on Sundays?

John Tate
Norfolk Aeromodlers

No I fly ouy at chesapeke TRC field. is the weather is nice will be out there tomorrow

http://www.flytrc.com/flytrc/Welcome.html

Come out if ya want.</p>

I have two Avistar's with .40 La's, I'm running a 10x6 Master Air Screw on one and a !0x6 Zinger wood prop on the other. They both fly very well, I seem to get a little more speed with the MAS, and a little more pull (quicker take offs) with the Zinger.  I have tried 10x7, 11x6, 9x6, in APC and Master Air Screw on these planes. They just seem to like the 10x6 MAS and the Zinger better. I also have another Avistar with a Magnum .46 and it seems to prefer an 11X7 APC.  Don't know why this is, but it's just my personal experience from my style of flying.

To make the Superstar fast you need a more powerful engine.

To go fast with a 40LA you need a smaller, lighter, more slippery airframe.

To get either you probably will have to spend money.

Flying from grass runway, my best combination were:

Bigger wheels, lite type
Higher landing gear
Non-baffle muffler
10x6 APC propeller
15% nitro fuel with mix of syntetic and castor oils

Enough to take off, but not too quick flights,.................well, it was a trainer anyhow,.............training and speed don't mix!

I liked an APC 11x5 the best on my .40LA.

Get rid of the remote needle and muffler baffle.I have a 40 la with this mod and it gave it close to 800 rpms.Throttle responce is instant with a 10x6.

I've always flown the OS .40 FP and LA series engines on either a wood or MAS 10 X 6 prop and 15% fuel with at least 50% castor oil (50/50 castor/synthetic). This seems to be the best combination for me. Don't expect a lot of power from the LA .40, and if you want good performance look for a plane like the Phoenix Sonic 25. The .40 LA doesn't put out much more power than the .25 FX.

Hogflyer

By removing the baffle is there any damage done to the engine? there is always atrade off, but what is it?
also when the muffler is apart how do you get the baffle out? is there anyway to do it so if i want to put it back inlater i can?

No as long as you keep it a little on the rich side. The baffle is inside the rear of the muffler. You need to remove the nut from the back of the muffler and remove the end. After you take this off you will see a small disk inside it. Remove the disk and put the muffler back together is the same order you took it apart. Just make sure you get the nut and bolt tight. this will give you about 5 to 600 more rpms right off the bat. But you will also need to readjust the carb on the high end. Happy landings. Ernie...

do i just take neadle nose plyers and pull?

The trade off is a little higher fuel comsumption, since some fuel will escape before the piston closes the exhaust port.

The idea is to facilitate the breathing and to increase the intake of the fuel-air mix into the crankcase.

For some two-stroke engines, just for experimentation, I have polished the intake of the carburetor, have aligned the hole of the throttle and the carburetor throat, have aligned the discharge of the spray bar exactly to the center of the ventury, have added a scoop to redirect the blast of the propeller (in an angle) into the carburetor.
All with good but not spectacular results.

Better off is a tuned pipe, and a correctly tuned engine.

A good reading about tunning can be found here:

http://www.flyrc.com/articles/tune_your_engine_1.shtml

The baffel will just fall out. It's just a round disk with a hole in the center. the back half of the muffler holds it in place. It is really used to keep the noise down. But it robs power. And yes you can reinstall it. with no harm to the engine of muffler. 

I guess this is the baffle

you got it. Now put the muffler back together and have a ball... Be sure to tach your engine to se the difference. Ernie..

In addition to being louder, it is possible that the exhaust pressure to the fuel tank will be reduced. If it is reduced, that could lead to fuel delivery problems as the tank gets close to being empty. There is no way to know if it will be a problem without trying it.

One local field has noise restrictions. I have no idea if an unbaffled muffler would be allowed to fly there.

Carr beat me to it, it does reduce the pressure to the fuel tank but I have never had any trouble with that on an LA series engine. There is a slight rise innoise but nothing that anyone will notice.
The couple of extra RPM you may or may not get is something you probably will not notice. The best thing you can do is save your money and buy a good .46, even the .46 LA is a power house compared to the .40. Iran the .46 LAs in all my fun fly planes, it was a perfect match for the Tower Up-Roar.
The .40 was designed for trainer type of planes where too much speed or power is a bad thing. The price of the engines make the LAs the perfect entry level engines but if you are looking for a power house you are beating a dead horse.
My thinking was for the manufactures to just quit making the .40 engines and stick with the .46, they have a lot more applacations in the hobby and almost no difference in price when you find them on sale.

Ok so strange turn of events, I traded a guy at the LFF an old radio for a OS 46LA, huge difference! but when looking at my old engine I found that one of the back plate screws were missing, I have no idea when the screw came out but we figure that it was the cause of my engine running very rough.