Question for you guys/gals:


I have an OS .46 FX engine that is brand new. What is the proper procedure for breaking an engine in?

Should I buy one of those engine stands to do it or put ion on the plane?

If the engine stand is the way to go, any reccommendations?

Thanks,
-Jim

Go here for everything you need to know plus more!

http://www.rcuniverse.com/showthread...engine+breakin

and no, you do not need a test stand. You can do the break-in on the airplane. Will give you a chance to tighten everything comes out from vibration before putting it in the air...

As a side note, make sure you get an instructor!!

With an O.S. I would do the break in with the engine mounted on the plane. as far as the procedure goes it is pretty straight forward. This is straight out of the book.
1. Install the proper propeller for your model. open the needle valve 2-21/2 turns from the fully closed position and start the engine. Run the engine for 2-3 minutes with the throttle fully opened but with the needle valve adjusted for rich four-cycle operation.
2. Now close the needle valve until the engine speeds up to two-cycle operation and allow it to run for about 10 seconds then reopen the needle valve to bring the engine back to four-cycle operation and run it for another 10 seconds. repeat this procedure until the fuel tank is empty.
3. Refer to idling adjustment section and fix the idling position where the lowest possible r.p.m. with steady running is obtained.
4. Re-start and adjust the needle valve so that the engine just breaks into two-cycle from four-cycle operation, then make 3-4 flights avoiding successive nose-up flights.

Thanks for the link BottleRocketWar.

I'm joining a local club on Thursday.

I would recommend doing as Lee suggests for two tanks then go fly. The only thing I would change is during the second tank, make the rich runs progressively shorter and the max rpm runs progressively longer.

Unfortunately, this is WRONG for an ABC engine like the 46 FX!

Others have said that OS is putting the OLD instructions in with the FX series engines, I guess it's true.

Running an ABC (or ABN) engine rich will ruin it. So if anyone has used these instructions, as far as I'm concerned, they should write to OS and demand a replacement engine.

ABC engines have an Aluminum piston in a Chrome plated Bronze sleeve (ABC), or Aluminum piston in a Nickel plated Bronze sleeve (ABN) which the OS's actually are.

Because of the different rates of expansion of the piston and sleeve, the sleeve is bored to a taper making the piston/sleeve fit "squeekey" tight at top dead center. (Sometimes they're so tight it's difficult to turn them over when cold.)

IF you run one of these "4 cycle" rich, the excess oil/fuel will not allow the engine to get to operating temperature, and the piston will rub against the sleeve causing excessive wear. The end result will be too little compression for a good, powerful engine.

Proper break in? Tune the engine until it's completely 2 cycling (at full throttle obviously) but not peaked, and run it for 3 to 4 minutes. Shut it down and allow it to cool enough to touch the cylinder head.

Restart the engine and repeat. Run through at least 2 to 3 tanks this way, then you can fly it. Do not lean the engine much beyond the break in setting until you've run a couple more tanks through it.

Of course, you never run an engine at "peak" RPM, always at least 300 - 400 below peak. (They lean more in the air when the prop unloads.)

Good luck,
Dennis-

That's good to know Dennis. Thanks for the information. One more question if you don't mind, "What does 4 cycle and 2 cycle mean?"

Thanks,
-Jim

I'll "me too" with Dennis' comments on break in. I wish OS would update their instructions. Btw, the best break in info I've seen came from the Jett website. Dubb Jett is a guy who KNOWS engines, so I trust his word on such things.

2 cycle is the engine firing on every revolution, in 4 cycle, the cylinder only fires on every other revolution of the crankshaft. Basically you get 4-cycling on a 2 stroke engine by richening it up. You can really hear the change, starting rich, from a 4 stroke, to a transition range where it's firing on most revolutions but still missing on some, to a "clean" 2 cycle. Once you hear it, you'll know it.

Here is the Jett website-

http://www.jettengineering.com/

Click on technical specs and isntructions and scroll down a little to Engine Break-in. There is a slo a lot of other good information on that page...I forgot all about this!

I agree with Dennis if it matters...

Thanks guys. I knew I could count on you all to help a newbie out.