Higher nitro fuel makes engine finicky
 

I just recently bought some new fuel at the hobby shop the other day. I thought it was only 5 or 10% nitro, but when I flew my plane I realized it had way more power than I was used to. I've never been able to take my Tiger 60 vertical before! But I also can't seem to get my engines to run consistently. Often times they will throttle up just fine for take off but then either right when I throttle up other times or in the middle of flying, the power would sag, or even die all together in one case. I've limited out radio interference because the throttle is the only channel acting weird, and the radio has been in great working order and I haven't dropped it or anything yet. The new fuel is Wildcat brad 15% nitro with 18% oils. It's within the recommended fuels for my Magnum .61 XL. Do I just need to play with the needle valve some more, or do I need to get some different fuel. Oh, and I believe the previous fuel was Byron 5%. Thanks for any help.

Silent J

Higher nitro fuel makes engine finicky
 

J, a little tuning would cure it. But why not just buy a jug of 0% and mix it 50/50. 0% and 15% together will get you 7.5%. This is close to the 5% you have been runing. later daveo

Higher nitro fuel makes engine finicky
 

Generally when you increase the nitro you need to open the main needle valve some. The higher nitro fuel burns faster and hotter, making the engine consume fuel faster. The 15% fuel is a big jump from 5%, and may take 1/2 turn of the needle. Just going from 10% to 15% required a bit more than 1/4 turn on my .40 class engines. (I'm still running 10% in my .61s.

Higher nitro fuel makes engine finicky
 

Well, Daveo, if I wasn't a poor college student, I'd take your advice. ut I won't be able to afford more fuel till a few days in June. So I still may do that. I was just at the field today actually. Too beautiful of a Friday to pass up. So I spent some time fiddling with the engine. I tried everything from 1 turn open to 3 turns open. But here's some weird behavior... When I first started it up upon arriving, it ran fine. It transitioned nice, idled nice and had a proper high speed needle setting. Then as soon as I set the thing on the runway, I throttle up and it dies. I take it back t the table and begin fiddling some more. I couldn't get the throttle open more than a few clicks without it dying. I worked on it adjusting the needles and such, but could not get it figured out. Man am I confused...

Higher nitro fuel makes engine finicky
 

It now sounds like you've got some debris in the needle valve. Pull the needle assembly, remove the needle valve and look through it and I bet you see a piece of something in there. Clean it out reassemble and you should be able to properly tune the engine.

Or... if you had a rough landing... hold the plane nose up, and shake it up and down a couple of times. The clunk could have gone to the front of the tank, kinking the fuel line.

Somewhere you have a fuel flow problem.

Higher nitro fuel makes engine finicky
 

Thanks for the advice. I'll check it out... Silent J