Lefte

My Feedback: (1)

Hello Everyone,
I have my first 4 cyl engine, a Saito .72 brand new in the box that I am breaking in per the manufactures specs. So far I have run it at 4000 RPM for 10-15 minutes and closed the high speed throttle from the 2 1/2 turns to 1 and 1/2 and started running it up never more than 9000 RPM. I have ran 1 tank through it and started on the second. About half way though it seized up and stopped at about 6000 RPM. I had it running for about 15 minutes at idle before that. I was sure it was frozen. I worked some after lub oil into it and everything loosened up fine. I tried again and the thing is smoking hot after about 2 minutes and the spit test flash boiled. I have a 12X6 prop and am using Cool Power "Green" fuel at 15% nitro and the correct factor installed glow plug.
The last thing I want is a dead engine, can anyone please provide some guidance?

Thanks
Lefty
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bhole74

If you are using the regular Cool Power and not specifically the 4-stroke Cool Power, you don't have adequate oil content. The 4-stroke blend contains 18% oil but the regular does not state an oil content (at least not the last jug I bought). Try switching to a fuel containing AT LEAST 18% oil such as Wildcat 2 & 4-stroke. I had a similar problem the first time I ran my 70 Surpass, but it didn't seize, just ran hotter than he**. I switched all my engines to 18% oil and they run much cooler and 400-600 RPM faster. Good Luck.

Campy

My Feedback: (1)

I have a Saito 72. As bhole74 said, make sure it has at least an 18% oil, especially during break in.

You will need a tach to set the engine properly. The engine should be producing "smoke", especially at full throttle. If it is not producing smoke, you either have insufficient oil or are running it too lean.

After 2 or 3 tanks through the engine it will be reliable enough to fly, but it will need about a gallon through it to completely break it in. About every 2 gallons of fuel you will probably need to adjust the valves. You will know when - the power will drop off a little. I run mine inverted with no problems. I suggest hand starting rather than using an electric starter. I also suggest using a drop of locktite on the set screw for the needle valve extension, they tend to vibrate loose.

MinnFlyer

My Feedback: (4)

Maybe that's the problem?

Bring the engine to full open throttle, and open the high-end needle until you are blowing some smoke out, then, open it a little more.

Cool Power is 17% oil, that should be plenty (It's what I break all of my engines in with)

daveopam

My Feedback: (9)

I think you have it too lean. It should only run about 6,000 wide open for the first few tanks. Run it so rich it will die without the hot shot. It should be spitting fuel from the muffler and the over flow.

david

Stick Jammer

MinnFlyer and daveopam are right. You leaned the high speed needle too much and WAY too soon. 10 - 15 minutes is not nearly enough run time to be crankin' at 9000 rpm's with a lean setting. Read the break-in info again. I don't think you're following what is recommended. As already mentioned, Cool Power 15% is fine.

bojangle

I have been reading a couple of articles by Dave Gierke ( Model Airplane News), one on Break-ins in general, another on 4 stroke. According to him, just running sloppy rich continually might not do the job. Quote: "Break-in requires short running periods during which the needle valve is occasionally leaned to a point where the engine comes up to speed and temperature, then is immediately richened to cool it down".

I have been trying this, and seems to work good. It's called "heat cycling", letting the parts heat up and cool down. The key word is "immediately". He also recommends no castor oil, which he says removes needed heat from the engine. I'm not sure about this, more study needed.

"For a ringed engine, there is a visible sign that break-in is probably complete, when the machine marks have disappeared from the visible edge of the compression ring as viewed through the open exhaust. "

The old lapped engines needed to be run very rich until the parts wore to an acceptable tolerance. We used to say a broke in engine was a worn out engine, not far from the truth. The newer engines have a more precise and consistent tolerance due to CNC, it's more a matter of relieving stress from the metals.

BO