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Old Nov 14, 2012, 08:28 AM
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United States, CA, Tehachapi
Joined Jan 2004
338 Posts
Good info all, and it looks like you were careful cleaning it up.
The older engines had softer finishes and really need some castor to protect them. I typically ran .049’s on 15% nitro with 10% castor and 10% synthetic (though 25% nitro was easier to tune). The Tower Hobbies stuff is good (better be for $1 per flight). I've found Sig is better if you can get it.

I had a few swapmeet engines that were really gummed up when I got them but ran fine… for a while. Over a few flying sessions, they started to lose compression and power. While trying to troubleshoot, I looked into an exhaust port and they were squeaky clean inside… The synthetic oil (and who knows what other additives) had eaten away all the crucial glazing and varnish that was keeping the motor viable. Was a Powermaster blend… but I’m sure they changed their mix since ’93. The true 1/2A fuels are typically 20% pure castor, and definitly a better bet for an older small engine.
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