Having a minor problem with my Saito 120. Cranks easy, runs great on the ground. Point it straight up and engine still runs excellent.
But, takeoff and go vertical and the engine just quits. It seems to have soemthing to do with vertical attitude and forward motion. It didnt do this at 1st, its just started it in the last 10 or so flights.

Any ideas?

Are you using a pump?....If not you may want to check the clunk in the fuel tank if that is okay then you may want to check all your lines...if everything is good I would try to richen it up just a bit.....other then that I dont know....I hope this helps you ....JW

No Im not using a pump. Not yet anyway. [8D]
I also tried richening up the mix until the needle came out, that didnt work.
Im going to doublecheck the clunk and make sure it isnt doubled over in the tank. Im also going to pull the cowling and tank and check the pressure line for a crack or a hole, that would do it.

I dont understand, it ran well last week other than expected problems during a waterfall without a pump, now it wont run reliably in flight... I dunno what would change setting up for a week??

Make sure your tank line (clunk) is not too long and the clunk is not hitting the back of the tank. Also, I use a larger size fuel line for the intake side of the tank, all the way from the clunk to the carb. with zip ties securing all of the fittings. Have never needed a pump on eother of mine and I have the tank mounted over the CG on both of my 1.20 powered planes. The Saito's draw fuel very well so a pump isn't really needed. However, the fuel line that comes with a lot of ARF's fuel tanks is to small for this engine to draw sufficient fuel under load and sometimes will stretch on uplines, allowing the clunk to hit the back of the tank, cutting off the fuel supply.

Hope I helped.

Thanks Guy!
I am going to change my fuel line in the tank and see if that helps!!