Hi

I have been offered an unrun F91AC at a good price and I'm pretty sure I'm goign to go with it, but have a couple of questions. Firstly it will be my first 4st engine, and it seems from other posts that they can be a bit of a pain to set up. Are they really that much more difficult than other 4st engines or is it a case of its easier to get into a cycle of tinkering for the wrong reasons with them ? Secondly, I run all my other engines on 18% synthetic 10% nitro, will the YS run ok on this ? a lot of people seem to be using 20% nitro, but is this just to get a bit of extra performance out of it ? I'll be fitting it to a Kyosho Spitfire 90 which weighs about 10lb so out and out power is not what I am after as it should haul it along quite nicely therefore hoping that the nitro thing is just a preference of others and not a necessity.

Thanks

Ed

The YS has a different fuel delivery system than your run of the mill 4 stroke so setting it up takes a bit of learning. Once you understand the YS engine they are a dream.

As for the fuel you want 20% lubricant and preferably synthetic. They will run on less than 20% nitro but the needle valve settings are more sensitive and you will down a little on power. I personally would get the engine and some 20/20 fuel made for YS engines.

If you use castor based oil it will gum up your regulator, and if you use less than 20% synthetic, you run the risk of overheating it and voiding your warranty. YS says very clearly to use 20% or better synthetic oil only, and recommends 20% or more nitro. If you go with 30% nitro, you might want to up the oil to 23% or so because of the extra heat that will be produced.