RC Fuels Nitromethane, Castor Oil, Synthetic, heli fuel, 4 stroke, etc...Fuel Q&A is here!

Break in

Old 07-15-2003, 05:31 PM
Phantom II
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Default Break in

I have posted this question on the Wildcat forum also, but I wanted to ask you as well. I have my 75 ABC airplane engine bolted down ready to break in and I have a Thunder Tiger 70 sitting in my heli also ready to break in. I have a case of Wildcat 15% Nitro with 18% total synthetic oil for the airplane and a case of 20% with 18% total synthetic oil for the heli. Can I break in these engines with this fuel, do I need to add additional oil, does it need to be Koltz if needed and what indication do I have that the engine is actually broken in? I understand the formula that mentioned on this forum completely that is used to change the percentage of total oil.
Old 08-15-2003, 12:09 AM
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Default Break in

As break in fuel, I use 5% nitro, 18-20%, 50/50 castor/synthetic, plus 4 oz. extra castor to the gallon. Got this from Clarance Lee in RCM (although I see he now does it with 10% nitro). If it's hot out use 5%. 10% could be more likely to preignite in hot weather which I believe could be quite damaging during break in. Just my thoughts.
Old 08-15-2003, 02:44 AM
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Default Break in


Your fuel is fine for break-in.

On the ABC engine, don't run it blubbering rich, peak it and come down about 800-1000 rpm and fly it. They need to warm up good to begin the seating process. After that, 2-3 clicks per tank until you get to the sweet spot.

The Heli motor I think is ringed, so run it very rich to start for the first few tanks, just barely enough power to hover. Then start creeping up 2-3 clicks per tank. Somewhere around the 6th tank or so you'll be there.

Don't add any extra oil; not needed. Castor not needed or desired either.

Castors benefit in todays motors is to help protect against excessive heat during a lean run. If you take care not to do this, you will be rewarded with a long-lasting motor that is varnish free, and will look new pretty much forever.

I have been running nothing but synthetic since 1986 in every type of modern motor made, the stuff works just great.

I respect Clarence Lee very much; but old habits die hard; i.e. castor oil.

Of course; just my experience and opinion; but I've not lost a motor since I switched, nor has anyone I've known unless they ran it super lean and hot for multiple runs.
Old 08-15-2003, 03:40 AM
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Default Break in

While I'll agree that with care you can get away with using an all synthetic for running in, there are two areas of the engine that will definitely benefit from having a little castor in the mix and that's both ends of the conrod (which also need to be run in). Castor polarises to metal which, although not strictly accurate, can be thought of as being magnetically attracted to metal. That means it wants to stay in contact with it. Synthetics don't work this way which means it's much easier to squeeze it out of running surfaces. There are some synthetics which supposedly have a polarising additive but it's probably just a bit of castor anyway

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