Debating on purchasing the YS FZ 115 S with the newer style reg. system . I have owned around 20 different YS 4 strokes in the past 20 years from the 63 size thru the 160 including all the newer designs in between. I am trying to find out from you guys who have the newer 115 with the regulator in the rear side of the motor on if they are a better and less troublesome regulator system than the older YS motors with the tranditional regulator system up front which seemed like always required maintenance and leaking fuel when the Regulator plunger or Regulator stuck open. Just really got away from the YS motors for a period of 5 years and went with Saitos. I really love the sound of a YS and of course the power .I have always used YS 20/20 fuel either Heli version with 23 % oil 20 to 30% nitro. Any opinions would be appreciated on the 115 . I might add this motor wont be used for pattern it is actually going on a 8 lb aerobatic type plane and would probably run the APC wide blade props. I like their downline braking and wide blades for hovering ect.

The newer engines run well. i use them for warbird racing and run the 115 WS. The WS is set up for high Nitro. if you going to use in a 3D type plane and you can wait a couple of months YS will be coming out with a 115DZ. This engine will be perfect for you as it makes more power in the lower RPM range over the regular 115's i would think you could run 18-19" low pitch props on it.

Ok I already ordered a regular sport version I will be flying it on a plane which only weighs around 8 lbs . Its actually the new Sig 4-star 64 arf. Sig got new owners awhile back and finally are putting out some good arfs planes. I fly mostly 30cc and 50cc 100 cc aerobatic planes like the edges and extras . This plane will just be a plane I can throw in the truck and go fly and have fun. I think the regular 115 will be more than enough power with a 17/4 wide blade prop. The plane is designed to fly with a 60 to 95 cc 4 stroke. Thanks for the info .

That 115 is equal to a OS 120 AX when on 20% nitro. I dont think the 17x4 will be enough prop but never know the biggest prop I have run on mine was a 14.5x14.5 on 50% A 14x12 is a good prop for break in. in flight.