hello, i just bought a used heli with ys f-91ac, does anyone have this particular engine or know the engine very well?

There's a lot said abvout them on the web. Do a search on google. There tuning and set-up tips there too.

Jim

w8, oh i did find the setup, tuning etc.. my question was, this engine needs air chamber, rear of cyclinder(outside), but the previous owner did not have one he lost when he took it off for the muffler somehow damaged he did not say, if looking at it from the rear the right side where muff goes it added a priece of metal like the engine material itself, no holes for the air chamber on the right side, he jb weld on it look cleans but, i rather have it weld with no jb weld compound in the air chamber compartant since it feeds into the same carb unit. do you know if or what kind of weld can be done to the air chamber to the mounting part of engine?

I hope the guy who sold it to you wasn't a friend, because it sounds like you've been had.

You need to remove the prop and slip a new Y - S engine in it's place and use the one you have for a weight to hold your parts on your model until the glue dries.

Good luck,

Jim

Or, contact Dave Shadel at YS Performance and arrange to send the engine back to him for service.

John

thanks for your insight guys...