scottm50

hi - got to the stage where i need to buy an engine for my gp super skybolt but can't decide between an os91 or 1.20 four stroke surpass - any thoughts or experiences welcome.

ggraham500

My Feedback: (4)

My personal choices would be a Saito FA-100 (adequate) or FA-125 (more power). Either would do the job and sound great.

scottm50

had thought about the saito 100 but have only had os - how do saito's compare with os?

MinnFlyer

My Feedback: (4)

Both are good engines, but I'll take an OS any day.

If this is the KIT version of the skybolt, a 91 will fly it well, but something more will be even better. I had a YS 91 in mine and that was a nice combo. If I were going to build one now, I would consider either an OS 120 or the new OS 110

ggraham500

My Feedback: (4)

I have many Saitos. Very dependable. Strong. Great sound. The four-stroke engines have been around for years and can take an incredible beating. I have driven them straight in the ground from an unplanned vertical dive (ok, crash!), pulled the engine out of the ground, cleared the dirt from the carb, installed the engine on another plane and flew again the next day. Heating is no problem as long as you do not run them lean.

The OS engines are fine. I also own a YS-120, etc. but I keep going back to my Saitos. I buy them used on eBay or from other rc'ers with nary a problem ever. Parts are always available (many interchangeable). If one is totally misused and needs a bearing replaced, not a problem ... standard or ceramic bearings are easy to replace.

I rarely (I mean like once a year) make a minor adjust on the hi needle. Once broke in, I adjust the low end needle once period. That's it. I run all my engines on Wildcat 2/4 cycle 20/20 fuel (also called YS-20 fuel).

Enough?

smithcreek

My Feedback: (25)

I have an OS-120FS on mine and it's a great engine for the Skybolt. Most likely you'll need the weight anyway.

Insanemoondoggie

I have a Saito 1.00 in mine and it,s a nice combination.

scottm50

thanks - saito 100 or os 120 it is

brianjt

My Feedback: (1)

Hi

I've been flying my Skybolt for 12+ years now and it's original motor was Satio 1.20 which flew it very nicely, I swapped it out for a YS 1.40 and it's like a rocket now, but you know what they say, if a little is good allots better..

YS are some of the best, but they are pricey, I think that the choice between OS and Satio is a personal one, I've had a bunch of each, they are both top drawer products. Either way, good choice on the 1.20, the Skybolt is spectacular with a big 4 stroke.....

Brian

Auburn02

My Feedback: (1)

Nothing like resurrecting a thread from the dead.

Anyone with a four cycle 1.20 on their Skybolt have any pictures of the engine install? After only a handful of flights on mine (it's the ARF) I yanked the OS .91 Surpass off the nose and am installing a Saito 1.20. I already know I'll probably have to hack up the engine mount to make room for the carb and intake, but I may also have to cut into the lower firewall for the exhaust. Just curious to see how others did it.

Of course the easy alternate is just sliding the engine further forward and have a nice 1" or so gap between the cowl and the spinner.

davidgeorge212

I just got a kit version of the super skybolt. I dont have any engine for it yet but has anyone put a twin cylinder in this plane? What would an Ideal twin cylinder engine size be for this .60 size skybolt?

Sandmann_AU

Once again, a dead thread resurrected. I'm currently building my second GP Skybotl kit. My first one started life with an ASP 1.20 4 stroke, then got upgraded to an OS 1.60 Gemini 4 stroke twin cylinder. It looked & sounded great but really that's about all I got from it. The 1.60 twin puts out about as much power as a 1.20 (due to the extra friction from the second cylinder), can turn a bigger prop, but doesn't spin as fast. Due to the need for a bigger prop I had to go to a 3 blade to get the ground clearance to land it. I also had to reinforce the horizontal stab with rectangular carbon fibre tube spars because it kept snapping when coming out of dives, due I assume to the extra weight (you could also use flying wires instead). It needs stand-offs to get the engine far enough forward, and you have to do a lot of work to the cowl. There's no way you can get both cylinders into the cowl at once, so I ended up cutting most of one side out so I could slide one cylinder in then wiggle the second in. I made a fibreglass panel that was held in place with sheet metal screws to replace the side. I also had to make a "scoop" underneath the cowl to cover the exposed carb.

All in all, an interesting mod, and as I said it looked & sounded great and got a lot of attention at the field, but just wasn't worth the effort. I ended up putting the twin into a large Spacewalker where it suits much better, and went with a Saito FA125a for the second bolt. (The first one met an untimely end when I was flying it while thinking about something else.)

Zor

Scottrn50,

Your question is touching the long existing controversy and group opinions.
Some swear by OS and others by Saito. Others as well are favored.

There is likely no answer to your question since asking people why they prefer one over the other or why they went OS or Saito rarely (if ever) brings outspecific reasons.

EXAMPLE: In my case I have bought a Super Tiger G90 and installed it on the fuselage with the cylinder sticking out on the starboard side of the cowling. It did not look good (a matter of opinion). The main reason I went that way was cost. Less then $200.00 at a time of restricted finances.

Before I flew the Super SkyboltI came into a bit of cash and I had dreamed of a four stroke. So I went for what I thought was the most reputed company that specialized in four strokes, namely Saito. Knowing that the the geometry was basically the same I hought a Saito 125 and this time installed it inverted (actually 20 degrees off the vertical) so that the plane looks better (opinion again) from both sides.

In case you have not seen and may be interested there is many pictures to be seen if you scroll the thread "Skybolt Hangar and Clubhouse" in this building kits forum.

Have a look as you wish.

Zor