Bax,

I'm getting a new 1.40RX. I have a couple of questions on proper break-in.

The manual states:

"Start the engine and open the throttle. Close the needle-valve gradually and allow the engine to run at its maximum rpm for just one or two seconds, then immediately reopen the needle-valve a half turn and run the engine with this rich mioxture for 5 to 6 seconds. Repeat until tank is empty.......not more than 10% nitro."

Here are my questions:

1. I only have 15% Cool Power available. Can I use it or do I have to wait until I can find some 10%.

2. The above sounds like you start the engine, run it up to full throttle, then go crazy playing with the needle going back and forth until the tank is empty. Is this correct - wide open throttle.

3. If I do this one tank ground break-in, can I then go direct to flying and just keep it tame for a couple of tanks.

4. Any general comments on break-in are really appreciated.

Thanks, Steve.

I'd do as the manufacturer recommends when it comes to nitro - if it says 10% or less than that's what I'd use....

As far as the breakin procedure, it is all done at wide open. If you're using the OS pipe, it's a little wierder. The motor will fall on and off the pipe as you lean and richen the mixture according to the instructions.

When I did the breakin on my 1.40 (now R.I.P.), there was a hair-trigger spot in the needle setting - one click or so leaner and the motor jumped on the pipe and ran at a howling 2-stroke, two or three clicks richer and it'd fall off the pipe and run at a super sloppy 4-stroke..... Like I said, that spot was hair trigger and made it very difficult to cycle the motor between 2-cycle and 4- or more cycle operation for the breakin. Also, the needle setting when the motor is on the pipe is very broad - i.e., close to an entire turn of the needle and the motor is still on the pipe and running pretty much at the same rpm. But to get it to 'fall off' the pipe and go back to rich running was only a couple clicks or so....

Made the breakin kind of a fight for me.....

If I had it do over again (and I might since I might be buying another 1.40), I'd do the breakin on a standard muffler instead so I don't have to chase the needle like that.

Mine only lasted for about 10 flights before the main bearings went rough like there was sand in the motor, so I had to take it out of service (and then I sold the plane).

Pretty sure my copy was defective though, probably one that sat on Tower's shelf for a year or so gathering rust on the bearings before I finally bought it from them......

But man what a motor..... unreal power and quiet as a lion stalking her prey.......

LS

Do you think you lost your bearings due to poor run-in? I have also been thinking about putting the engine on a 1.20 Ultrastick I have and following the inflight run-in procedure. Seems a lot simpler (easier) to do; and if I have a deadstick in the Ultra, a lot easier to handle than in my new (used) 2M.

Running-in an engine properly will insure it will give you a good service life with the power it's designed to have.

The initial run-in is intended to get the engine to the point where you can fly it as it continues to break in. Your O.S. Max 1.40 RX will break in over the first gallon or two of fuel. If you rush it, the service life and power will be reduced.

Once the initial running is done, the model can be flown with the engine at a rich setting. You'll gradually lean it to peak RPM over a series of flights. At some point, you'll be able to lean the engine to just rich of peak RPM and leave the needle there.

When running on the ground, the model is just about the worst place to do it, unless you can put the model on a stand or table a few feet up. Otherwise, the engine will suck in a lot of dirt and trash, which will eventually wear out the engine. Even on grass, you'd be surprised how much dirt can go through an engine.

Just follow the instructions that came with the engine, and you'll be fine. It's an F3A engine, and not a general sport-flying engine.

Well, now that I finally have the motor apart and am getting a good look at the inside, I'm less inclined towards my rusted-when-new theory. I'm now thinking the main bearings are simply not strong enough and mine were just hammered to death.

I was amazed when I pulled the crank this am at the teensy little main bearing. The crank is this huge monster but the main bearing is this tiny little thing in there......

No wonder the motor eats them up so fast. Close to 4 hp at only 9000 rpm, the hammering on that little bearing must be intense.....

Of course, I ran mine with the OS pipe which will make the motor work a lot harder than running it with a regular exhaust. That and low nitro fuel are what I'd suggest to get the power output down and thus save those bearings.....

LS