hi my OS 91 FX started to run very different than it has in the pastafter hours of fiddling saw a lot of air bubbles only- mid rangechanged the needle valve '' O'' ring and all got back to normal the plane and engine are 10 years old my pattern flying buddy told me he changes his nv ''O'' ring once a year as normal maintanence-i would like to pass this info on as this is often overlooked and can save us a lot of time fiddling at the fieldnot to mention dead sticks and engine damage from air leaks
i was running my 60 ULTRASPORT on an APC 13/7 @ 12,100 RPM i went to a 13/6 now at 13,300 RPM (top end RPM readings ) as i run my engine mostly at mid rangewere it sound richer than i would like it to (just do not like the sound it makes at midrange ) thought that more RPMS at midrange would help consume more of the fuel there it worked-like it better
when using the pinch fuel line -method to set the top end nvyou need to pinch the fuel line -just before the carb-with a remote nvyou will get incorrect feed back if you pinch before the remote nv-my low end when pinched has about a 3 second run up when it is set as it s/bthis is fresh in my mind as this just happened this week
i need to try the ultratrust muffler to see if it helps me enjoy the sound of the engine moreas i said i really do not like the way it sounds nowthe stock muffler always seemed to have a strange harmonic-as strange as the engine has soundednever once has it stopped running on me
another thing that is odd to me are the great number of different props that are posted in threads that this engine will run on from my 13/6 to a 16/4 but i do understand you prop the plane not the engine for performancevertical performance in a given airplane being the guage we measure performance by
my ULTRASPORT with the 91 FX flys and tracks on railsmore power than i could need-a super great flyer that gets its share of attention when i fly herejust got to get here to sound betteras i am very motivated to fly the planes i own that sound awesome in the airthats the rush for meOH WELL-working on that ENJOY REGARDS TONY