stunthanger.com
Engine basics => Engine set up tips => Topic started by: Allen Eshleman on March 26, 2012, 07:18:10 PM
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I just got a NIB O.S. 40 FP. It does not have the instruction sheet. What is a proper break-in procedure. I know I've seen it here but I couldn't find it. I have another one and I love it. Thanks in advance.
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I don't know which version you have, but the later ABN engines break in rather quickly. You could probably do it on the airplane. Using fuel that has about 22% oil and about a 9-5 prop, start it up and let it run with it adjusted to a very fast four stroke just barely breaking into the two stroke mode. Then about every 20-30 seconds slightly pinch the fuel line and let the engine break in to a solid two stroke for 10 seconds or so then let the fuel line go. Do those cycles for one or two tanks of fuel and it should be good to go.
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Clint has the correct procedure. It is better to break in any engine on the test stand. You should use a smaller prop than the one you fly with, in order to unload the engine. Cycling between 4 stroke and 2 stroke is the right thing. Better yet is to let the engine cool completely between several runs. Just make sure it is run-in enough to hold a strong 2-cycle without sagging or getting hot. Then, you can install a 10-5 or 10-6 prop and go flying without worrying about a lean run damaging the engine.
These engines are not fuel-critical. Many use SIG 10-10-10, which is 20% oil with half castor oil and half synthetic.
Floyd
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Thanks Gentlemen,
I appreciate the info. I got the similar recommendations from Randy over the phone. I didn't realize they were that easy to break in.
Allen
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It is better , rather than dropping down from say a 10 x 6 to a 9 x 6 , to use a 11 x 3 or 11x4 prop, this lets the engine turn up faster, doesn;t load quite as much and is much easier to crank and handle than the 9 in prop
Randy