OS .40 LA Break-In
11-24-2004 | 12:23 AM
#1
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From: Omaha,
NE
OS .40 LA Break-In
Just bought an RTF trainer with an OS .40 LA engine installed. I've heard that these engines can be a little tough in the initial starting and break in phase. Any info or suggestions on first startup and run-in would be much appreciated. Thanks
Martin
Martin
11-24-2004 | 07:41 AM
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From: Toowoomba, AUSTRALIA
RE: OS .40 LA Break-In
Ok, im pretty new too but i have one of these motors in a trainer too.
I followed the instructions in the manual to the letter, including the type of fuel etc..
Now i have a nice running motor that never stops in flight (unless i run out of fuel)
After the run in process i taxied my plane around the backyard for about an hour learning how to use the throttle,
all i can tell you on the technical side is what EVERYONE told me,
run it lean and you will kill it!
I followed the instructions in the manual to the letter, including the type of fuel etc..
Now i have a nice running motor that never stops in flight (unless i run out of fuel)
After the run in process i taxied my plane around the backyard for about an hour learning how to use the throttle,
all i can tell you on the technical side is what EVERYONE told me,
run it lean and you will kill it!
11-24-2004 | 08:44 AM
#3
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RE: OS .40 LA Break-In
The LA .40 is not known for its power and in some circles, a flat out dud but they do run well. Have somebody show you how to tune it in. Some people run their engines on a bench before installing. I feel that is a waste of time and just break mine in on the plane. Get it dialed in as best you can and once you get your high end leaned out, richen it up a couple hundred rpms. Somebody around should be able to show you how to tip the plane up to check the enging also.
You can also double check what youe done by running the engine at an idle and pinch off the fuel line by the carb until it dies. If the rpms increase before the engine quits, your low end needle is to rich. If the rpms just go down and the engine quits, low end is too lean
You can also double check what youe done by running the engine at an idle and pinch off the fuel line by the carb until it dies. If the rpms increase before the engine quits, your low end needle is to rich. If the rpms just go down and the engine quits, low end is too lean
11-24-2004 | 11:34 AM
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From: Winston-Salem, NC,
RE: OS .40 LA Break-In
But don't worry about the low end setting until after the engine is well broken in. My LA40 has never had an adjustment to the low end needle. If you can wait until you get to the field to try starting it, find someone with an electric starter. Mine was very hard to start at first. I went out and bought an electric starter. Now that it is broken in, I rarely use the starter.
11-24-2004 | 11:51 AM
#5
My Feedback: (32)
RE: OS .40 LA Break-In
To run in a 40LA I do this:
open the high speed needle 3 or 4 turns
attach the glow driver and leave it on through this whole process
start the engine and let it warm for 30 seconds or so (It will be blubbering and powering out fuel and smoke from the exhaust and will sound like a 4-stroke)
Take the engine to full throttle and hold it there for 10 seconds
Now turn the high speed needle clockwise to lean it just until you hear the pitch change to a high pitch scream which now says you are running it as a 2 stroke.
Let it run like this for 10 seconds and turn the high speed needle until it goes back to the blubbering 4 stroke sound.
Continue alternating between 4 stroke and 2 stroke sound and holding each for around 10 seconds for the entire tank.
The 10 seconds does not have to be exact but as close as you can make it.
After that tank is finished let the engine cool down. Refuel and close the high speed needle completely but do not over-tighten it, open the high speed needle 1.5 turns and start the engine but there is no need to leave the glow driver on after the engine is running. Now go to full throttle and lean the engine until it just starts to lose rpm then immediately richen it by 300 to 500 rpm (probably 1/4 turn from where it started to run rough and lean)
Go fly and avoid nose high flight as much as possible. After about 2 or 3 more tanks then you can adjust the low speed to get a great transistion from idle to full throttle.
The same procedure works well for all 2 stroke OS engines and after about 10 different OS engines it has never failed me once. On the rare occasion OS may have set the low speed too rich and you may have to lean it a 1/8 turn before flying the first time. You will know if you start the engine after you run the first tank, get the high speed set to max rpm minus 300 to 500 rpm and then snap the throttle shut the snap it open and the engine bluubers, spits fule and smoke and dies.
It will blubber a little and hesitate just after break but it should not die. The transition to high speed from low speed will be rough, but it should transition.
open the high speed needle 3 or 4 turns
attach the glow driver and leave it on through this whole process
start the engine and let it warm for 30 seconds or so (It will be blubbering and powering out fuel and smoke from the exhaust and will sound like a 4-stroke)
Take the engine to full throttle and hold it there for 10 seconds
Now turn the high speed needle clockwise to lean it just until you hear the pitch change to a high pitch scream which now says you are running it as a 2 stroke.
Let it run like this for 10 seconds and turn the high speed needle until it goes back to the blubbering 4 stroke sound.
Continue alternating between 4 stroke and 2 stroke sound and holding each for around 10 seconds for the entire tank.
The 10 seconds does not have to be exact but as close as you can make it.
After that tank is finished let the engine cool down. Refuel and close the high speed needle completely but do not over-tighten it, open the high speed needle 1.5 turns and start the engine but there is no need to leave the glow driver on after the engine is running. Now go to full throttle and lean the engine until it just starts to lose rpm then immediately richen it by 300 to 500 rpm (probably 1/4 turn from where it started to run rough and lean)
Go fly and avoid nose high flight as much as possible. After about 2 or 3 more tanks then you can adjust the low speed to get a great transistion from idle to full throttle.
The same procedure works well for all 2 stroke OS engines and after about 10 different OS engines it has never failed me once. On the rare occasion OS may have set the low speed too rich and you may have to lean it a 1/8 turn before flying the first time. You will know if you start the engine after you run the first tank, get the high speed set to max rpm minus 300 to 500 rpm and then snap the throttle shut the snap it open and the engine bluubers, spits fule and smoke and dies.
It will blubber a little and hesitate just after break but it should not die. The transition to high speed from low speed will be rough, but it should transition.
11-24-2004 | 10:45 PM
#6
Senior Member
RE: OS .40 LA Break-In
Bill just gave you one of the best procedures, but it's an OS, LA. Put fuel in it, run a tank of fuel through it like Bill just said, then get your instructor to check the rest of the plane out, hook up the buddy cord, and start having fun. Most OS non ringed engines get broken in, in the air, running a little rich, because they are so darned reliable and aren't at all fussy. By the way, they have an air bleed carb, that really is only a problem, when the temperatures get above 100 degrees or so. Some people take the baffles out of the muffler or buy a Macs mini pipe muffler for these to reduce weight from the stock muffler. Can't go wrong with any OS and the manufacture's instructions.
