Hey all,

I have a OS 40 LA (who would've known? ) and I cannot get it to stay on. In order for it to idol, I have to set the carb to halfway open. Then it will run at idol speed. But when I push the throttle up or down, the engine sputters and dies. I checked the needle valve, checked the fuel, the servo (don't know what that has to do with anything) the carb and the engine. When I opened the engine, there was a little oil left over from the fuel. So what should I do now? Does that mean my engines dead and I can get a new one???

http://www2.towerhobbies.com/cgi-bin...?&I=LXFMD5&P=0

http://www2.towerhobbies.com/cgi-bin...?&I=LXALM2&P=0

MORE POWER

Whats your needle valve set at? Is the prop spinning where air is pushing the aircraft forward?

Uhh...1. like 2.5 or 3 turns and yes.

On the off chance I have to buy an engine, can the .50 SX fit on an Avistar?

Well, there's your problem, you are running WAY too rich. MY OS 40 LA runs at it's highest RPM at about 1.25 turns out. When you start it, you should only have it opened up to 2 turns, then close it slowly until you get the highest RPM and then richen it up 2 to 3 clicks.

Also, I hope your read the instructions on breaking in the engine. The first full tank you shoudl get the engine running at it's highest rpm and then richen it up with about 180 degrees from the optimal setting and then let the first tank run out at full throttle. On a 10oz tank it should run less than 10 minutes running that rich. Then let the engine cool. The next tank you sould lean it out about 90 degrees from the previous setting and then run another full tank through at full throttle, then let the engine cool. The third tank you can either fly it, or do it on the ground, but set the needle to 2-3 clicks richer from the optimal setting and then run that tank through at verious throttle settings. At this point, with the factory low-speed idle setting your engine should have a very smooth low rpm idle.

The problem is, if I run it at about two turns, it doesn't get enough fuel. The needle valve is clean BTW.

I agree with connery.

If at 3 turns its too rich, and at 2 it doesnt get sufficient fuel, play around with it and find a "middle ground". These needles can be extremely sensitive. On my nitro RC car, 1/4 turn on a needle can make the difference between a one pull start and having to pull for a minute or two at half throttle.

If you can get it to start, then you're on the right track. just have a little fun and "play" with your needle settings until the engine runs well.

I have also found that the plastic back plate frequently leaks. Check for air bubles around the matting surfaces. If the back plate leaks the engine runs poorly.

My 8th grade English teacher has really changed me!

(i.e. it's Idle, not Idol.)

The engine idles.
I hate watching American Idol.

(Grr... I can't resist doing that!)

I also had the loose backplate problem. I used a little loctite on the screws.

-Scott

DItto on Connery and Snowball the needle too rich.... if it get's to start and then dies as you advance the throttle close the valve 1 or 2 clicks and re-start littel by little you'll be able to keep it running better as you advance the throttle u pt o ufll speed and then SLOWLY keep closing the valve until the engine drops rpms then back up (richen) as sonwball said.
I like my OS40's nice enignbe can keep up with toil and abuse (my two kids and me learned to fly on those ) ) the trick is to not lean them too much and then enjoy the ride

But...at full power it dies and at idle it dies...

I don't want to imply that you don't know what you are doing, but is there anyone that has been flying for a while that can help you tune the engine?

Yeah, everyone at the flying field helped but out of the 8 people, nothing worked. []

A couple of things to check.

Make sure you do not have a fuel system leak. Disconnect engine line and muffler pressure line. Block one with finger and blow into the other.

Check that one of your helpers has not completely closed the Air Bleed screw. There is a little hole in the front of the carb and a screw that partially blocks the hole. If this is completely blocked, back it out until the screw only blocks about half of the hole. Instructions for setting the air bleed are in your manual.

If the engine has never been run and is extremely tight at TDC then it can be very hard to keep running. My 40 LA was like this. Try heating the head of the engine with a heat gun before starting. You may have to run 3-4 tanks of fuel before the tolerances between the piston and the cylinder are right for cold starting. Search RCU for some threads on breaking in ABC and ABN engines. The proper break-in procedure will cause the tolerances to change without excessively wearing the piston and cylinder surfaces.

Carl

Hey,

Thanks for the help. I tried everything exept the heat gun thing. Think I'll try that this weekend.

Thanks again,
IBrakeForNobody

[:@] grr....another problem...

The engine idles at low, then when I rev it up to WOT then back down, it dies. And after about 20 seconds of idleing it dies.

I checked:

The fuel
The backplate
idle screw
needle valve (1.75 turns out)
throttle servo
glow plugs (the last 1.5 coils did not light up)(checked 4 plugs, 1 on engine and 3 NIB same on all)
glow plug ignitor (battery full)

Before, the engine wouldn't even go to full...at least now it does that. [>:]

Now, the carb is open about a little more than 1/16" for idle. I idled it up and it still dies.

Any ideas?

Thanks!

Mine did this too. I took it to the shop to get it tuned and wasn't there to pick it up. I think they said the servo was set up too far out on the horn though.... Made it move to fast or something like that.

k thanks...I'm gonna have to wait til I go to the field sunday I guess. At my LHS, they are RC car people. [&o]

Try a new glow plug

For now, don't worry about the idle. Get it to run at WOT - once it's running slowly turn the needle in (Clockwise). As you continue to turn the NV, you will hear the RPM rise, then level out, then the engine will start to sag.

At that point, turn the NV back (counter clockwise) until the RPM peak, and sag to the rich side. Then go about 3 or 4 clicks more to be sure the engine is running rich for break in.

Let it burn two tank fulls of fuel at that setting.

If at any time you hear the RPM decrease, like as if it wants to die, try pinching the fuel line. If it is dying because it is too rich, that should bring it back to a good run - then turn the NV in a click or two.

If pinching the fuel line kills it, start it again, and this time if it starts to die CAREFULLY put your finger over the carb for just a split second (NOTE: DO THIS FROM BEHIND THE PROP AND BE CAREFUL NOT TO GET YOUR FINGER, HAND, SHIRT SLEEVE, ETC. IN THE PROP)

Once you have the high end running properly, do the same thing at idle.

Thanks everyone! I replaced the glow plug and I'll do the break in process again.

Thanks again! [8D]

hi it sounds to me like you need to check the air bleed screw!!!,back it out a little then put a small sowing needle or pin in the hole at the front of the carb and slowly tighten the air bleed screw till it just nips the pin but you can still remove and insert the pin but you can feel it niping the pin a little.if its a new engine run it a little rich for a cpl of flights it should be ok.but it sounds like the airbleed screw to me!!!. hope this helps.

Fixed the airbleed and everything else and now it runs better.

I noticed some what looks like burns/rust on the engine...is that normal? If not, how would I get it off?





Thanks!

What are the white parts for?