OS v YS 91 in 700

[Cuppa]

re OS91HZ-R PDQ what a joy, after months of pain! first this OS motor fitted my 700 like a glove! unlike the ys91sr!, ongoing tail drif gone and have been able to tune it without to much hastle pulls like a train too, joy my advice to anyone thinking of putting a ys 91 in there 700, don't go there you could be opening a can of wormsWhere as the ys56sr in my 600 has been good as gold, also has stacks of power. happy days at long last. more fly'in less cry'in

[Rotorhead]

I've got an OS91HZ-PS in a 700, and its been pretty much spot on since day one, frankly I dont buy it when people say they are hard to tune, hate to say it but maybe some of the complainers are just impatient and dont take the time, just set it somewhere like, or in some cases dont know as much about engine tuning as they would like to think.

The only trouble I ever had with it in all of the last year is a bit of muck in the carb, but that can happen to any engine, and as soon as it was cleared it was cured.

[Cuppa]

I've been tune'in things for 30yrs bud! all my other heli's work great, i know it should have been the dog's as is my ys56sr. but this reare case of a dog sh*t motor can happen! and i would'nt want to pick one up clean end or otherwse

[chris jones2.4]

i brought a os91sz-h ps or my 700 and its been fine, everyone has said in the past either go for ys or non pumped