I have to give credit to Global Services for servicing my XL 91. I flew this engine in a 60 size Mustang. It flew very nice; throttle response was quick and the power was awesome for loop, inverted fly, tight turn, high-g turns,...The idle was nice. It also had good power at low speed, and helped me land the P51 like a dream. Unfortunately, one day I was stupid enough to fly in a 33 mph cross wind and had a crash landing. The carb broke. I sent it to Global Services. After about a month, they returned the engine back to me, nicely clean, with a long list of parts that were replaced, and get this: AT NO COST! They even test ran my engine and gave me its data performance. Just ask Farrell at Global Services, and you´ll agree with me how nice they are.
I like this engine because it flies well and less costly than the O.S and Saito, which I was thinking about when switching from 2 stroke to 4 stroke. The sound is fantastic, almost like a motorcycle. You just broke in about 1 hr, adjust high/low, test fly (I did 3; they recommend 5), and that was all. After that, just add fuel (I used 15% Omega, the same fuel for my 2 stroke engines) and have a good time. At full throttle, the fly time is about 20-25 minutes. My fellow club members kept asking me to land because "man, you´re up there for quite awhile"