can i use saito 91 or 100 on the flip 3d?

I wouldn't recommend it. Too much weight and you don't need the extra power. Keep the Flip 3D as light as you can.
A YS 63 or Saito 72 or O.S. 50 SX are the engines of choice and will be plenty of power. I have the YS 63 on mine and it will hover at 1/2 throttle.

Jim

I second that idea to much weight with a 91. I am putting a YS63 on mine cant wait to get it in the air.

i will use saito 72 on mine.

can i mount it inverted?

Yes, You can mount it inverted.

Jim

I have just about convinced myself to go with a YS.63 for my new Flip. I'd like to know how you guys are mounting them. Are they being mounted horizontally like the instructions call for or are you guys mounting them inverted? If the inverted mount works I would think that looks better?

Show some pics of your YS.63's mounted on the Flip.

Yes inverted a ys will run inverted with out onboard glow just fine. Many other 4 strokes will not another advantage of a Ys.

Here you go.

Jim

Here's a close up.

Jim

With the addition of an O.S. exhaust header pipe for the FS70-91S (part # 72109500) you can get the muffler to come out on the bottom of the plane. My plane stays very clean with this set-up.

Jim

One last pic for you.
Notice that the engine is not at the 6:00 position, but at about the 6:30 or 7:00 position. This allowed for the muffler to fit in the cowl better and come out on the bottom of the plane.

Jim

Is that the ys 63 muffler then with the os header ??n Looks nice

Yes it is the YS 63 muffler with the O.S. header.
Some guys even put the O.S. muffler on the YS 63 and claim it gives them more power. I have not yet tried the O.S. muffler. I like the way this worked out with the YS muffler this time.

Jim

Jim, It looks as if you dont have any ground clearance with that prop? Is that the case or just an optical illusion?

And did you cut out all of that cowl for cooling or what?

I have adequate ground clearance with the 14x4 prop. I'm guessing it is about 2 inches. I could use more, but it has not been a problem so far.
I used a Hyde soft mount on my YS 63. With the soft mount I get some movement of the engine and I had to allow for this movement by cutting away the cowl.
I do get good cooling this way also, which I believe is very important on a plane that is intended for 3D flying. I'd rather have the cowl cut back and not look quite as good than burn up an engine by overheating it.

Jim

I have a cazillion gallons of 5% nitro - 18% oil Ritches Brew fuel. Will the 60-75 size 4 strokes run OK on the 5% fuel? I really like that size 4 stroke.

Thanks,

JW

I have found that the YS 63 and really all YS 4 strokes like high nitro content. I have switched to the Magnum special "DZ" blend fuel with 30% nitro and use it on all of my YS 4 strokes with great results.
I've heard that the bigger Saitos (150 & 180) like the 30% nitro also, but I don't know about the Saito 72. I have never owned one. My guess would be that it would not like the 5% nitro fuel, but give it a try and let us know.

Jim

I have also switched to the Magnum DZ fuel in all my ys motors great stuff and it likes all four strokes according to the manufacture including the saito 72 You can get it shipped to your door for 18.50 a gallon including shipping Check Central Hobbies web site for the info