I bought a used tt extra from a guy who is a wiz at fun-flys and rc. It has an OS61SF which has caused me (and I assume him) a lot of grief. It refuses to run rich enough. He had apparently cut off the nedle valve to increase fuel flow. He had flipped the fork which adjusts the mixture with an eccentric screw (also to get richer or leaner- I can't remember which way it was turned). I fixed these, but continued the mixture problems. I finally realized it was rich then got leaner after 1/2 tank and always died (of choking) in spins. I pulled the tank. The fuel supply brass tube was all cracked with tiny hairline cracks at the bend. Sucked fuel with full tank- got lean at 1/2 tank- drowned in fuel nose down in spins. The brass tube looked rotten. When I flexed it, it split all apart. I am fairly new, and have never seen an engine run long enough for the tank lines to corrode like this before.
Tom

Actually brass does this, the zinc in the brass causes the alcohol to turn to acid. Replace the brass tubing with copper tubing and you shouldn't have this problem.

Am I wrong? Do the tanks come with brass or copper? It was the stock tubing, I just assumed it was brass. (If they come with brass it seems like they would switch??)(Yes, I know what happens when you assume...)
Tom

They come with brass or aluminum. Aluminum would actually hold up better and is cheaper, but many people have trouble bending aluminum so I guess this is why they use brass. Copper is fairly expensive so I guess that is why they don't supply it. Brass usually lasts a long time, I use it but often replace it with copper on expensive models, or after a failure, which has never happened in the air.