I have a Seagull Models .61 Yak 54, and need engine suggestions. I know I am going with 2-stroke but four stroke might do it for me, and .61-.85 size, but what brand? I want to be able to go vertical on 3/4 throttle while the engine still fits inside cowl without too much cutting, except for the muffler.

I had read about a saito 100 on one, so I put a saito 100 option. but if you have another reccomendation for an engine size than put a new message.

Your poll seems at odds with your question.

For a start Saito only make 4-stroke engines these days but you say you're going 2-stroke (huh?)

And what's a Thunder Power engine?

Ohh I thought saito made 2-stroke too. lol scratch that!

Ohh thunder power is a cheepy, I just put it there to take up space!!!

you say bigger than .75, Seagull said to use .61, what size should I use?

The thunder power engine may be less expensive than OS, but I think the overall quality is better, ABC piston and sleave, as good or better bearings than OS, the worst in the industry IMHO. I race a TP 46 pro against a host of OS powered buddies in the T-34 class. No one in the club has beat me overall at the end of the season in the past 5 years. Yea, I'm a experienced pilot, but going on 74, most of the other guys are 40's to 50's. Gotta tell you something about the engines overall ability. I get around 800 rpm more than the OS guys on the same prop. That 800 rpm is not a whole bunch, but enough to make up for old eyes and sort of poor start. Just wanted to let you know that OS is not king in everyone's eyes, and very over-priced in mine for what its worth. ENJOY

Thunder power?

Can someone point me to a picture of or advertisement for these Thunder Power engines? I've never heard of them.

The closest I can think of is Thunder Tiger but that's not ABC.

This one is easy, 61-85 size really means forget about everything exept a .91 engine. Todays .91 engines are bored out 61`s and since they are of the exact same physical size and share the same mounting space and bolt pattern, then why settle for the least powerful one????

For 3-D flying you need real power and a .91 will be much better that a .61, or .75 (never heard of a .85)

OS 91 FX is great, Magnum/ASP XLS 91 is just as great only less expensive, Super Tiger 90 is said to be great too

Xjet , I'm pretty sure they are refering to the thunder tiger (which is a good motor IMO). Keep in mind the age of the gent is 74


if you can afford it a saito would be a great choice for 3d 4 strokes are cool[8D]

If you want to fly 3D then *forget* the SuperTigre it's just not up to the job of providing the flawless throttle-response needed for good 3D flying.

With an all-up-weight of 6.4lbs, I doubt that *anything* less than a .90 will provide the level of performance you're looking for.

I'd forget about .61-sized engines, they're not much more powerful than a .46 but weigh (on average) about 50% more. Most .75-.90 sized 2-strokes are almost exactly the same weight as a .61 but put out around 30% more horsepower.

A nice Saito 100 sounds like it would be just the thing for that model. Light, powerful, excellent throttle response and mid-range etc. However, they are (moreso now that prices have gone up) very expensive.

The latest crop of OS engines are pretty good.. at a pinch, the OS75AX might be okay for that model but you'll be paying a lot of money for an engine that's really at the very bottom of the power-range for your desired performance.

Thunder-Tiger (not Thunder Power) engines are very good but I don't think they have one that would be a good fit for this model. The 75FS would probably be too weak for the kind of performance you're after and the 91FS will likely be way too heavy (it's the heaviest .91 4-stroke on the planet). Forget about the .61-sized Thunder Tiger engines - like all the other .61s, they're too heavy for their power output when compared to a modern .90-sized 2-stroke.

As for you not wanting to cut up the cowl too much I can understand that. A 4-stroke will probably require much less cowl-cutting than a 2-stroke because of the smaller mufflers involved but you could use a pits-style muffler with a 2-stroke although that's probably going to knock the power back somewhat.

So basically -

A Saito 82 or even a 100 would be my first choice.

An OS75AX would be my second choice.

________
When I'm not here I'm at [link=http://rcmodelreviews]RCModelReviews[/link]

I agree with you on all this, but why not the 91 FX instead of the 75 AX? The AX weighs 750 grams and the 91 fx weighs 770 grams. At 6.5 pounds the .75 will be marginal for 3-D and the fx 91 will be better. I fly my Katana 70 with a 91 FX and wood 15-6 prop now and it is just great. Idle and transition is great and the pullout from hover is ballistic (plane is 6 pounds). I use the Tower 75 muffler and that brings the total weight of the engine down to 700 grams (lighter than the stock .75) I just swapped out the YS 110 for the 91 FX and I like it as much as the YS in this plane.
I don`t feel that a fourstroke was any better than the two stroke

If the OS feels to expensive then the Magnum .91 is just as good (I have had that one too) and because the Tower 75 was weaker and about the same weight as my .91`s I ended up selling the Tower 75

I say go for a .91 twostroke if you don`t choose a bigger fourstroke

Sorry, double post, please delete

91 fx would be as good of a choice as the 75 ax (or better),, The Saito would be a better choice then the YS if wieght matters, the Saito 100 is much lighter

On a Mojo 60 the Saito 100 is the Cats meow, The YS makes the plane act heavy IMO, surprized me I thought the YS would be great, but I changed back to the Saito.

Saito 125 the only way to go I have one in an aero works 60" edge 540. Nothing compares nothing.. IMO 2 strokes are great for sport or faster flying but the 125 saito is tough to beat in this size class..

Not even the YS 110????

Thanks guys I think Im convinced, Im gonna go with a .91 2-stroke, but I cant decide from O.S. and Thunder Power. PLZ HELP!!
Ohh BTW I am going to use a pitts style muffler, b/c I want to minimize cowl cutting, and I also would later like to add a smoke system. But thats for a different thread. Plus it looks cool!

How about Evolution Engines?
and are they compatible with pitts mufflers?

Yes, the Evolution 100 is another choice and I think you will find Pitts mufflers to fit just about whatever engine you choose. The Pittsmufflers often present some issues with fuel delivery due to altered back pressure and tank pressure. Often one of the pipes has to be closed somewhat to get the engine to run reliable.

I understand what your saying, but I think a pitts style muffler would totally "make" the Yak. So Could I find one w/ smaller exuaust outlets, or would I have to close one valve, or both valves halfway

mine has a ys 110 though i havent flown it yet.

Nice that is a bigger engine than the OS .91.

You have a 110 listed in your poll The plane calls for a Max of 82 in four stroke,,, looking at it's stated wieght of 6.4 - 7.5 lbs min. I know it's not going to do any on the deck 3d with a 82.. And a heavier engine will kill it's wing loading. If your looking for a hoverbatic plane I would guess this is not going to be it. But if you have your mind stuck on this plane I would nix the YS and go for the lighter Saito 100.

i would have went with the saito 100 but didnt have the opportunity before the YS 110 came up. the saito is actually cheaper. but not to be argumentative but the box said one engine range and the website had another: Engine Size:.60–.75 2-stroke; .91–1.00 4-stroke

the YS is not so much heavier that it will be that much of a problem plus has more power than the 100. however this airplane if you look in the arf forums isnt good for 3D because of undersized ailerons. if it were me and i had the money to spend on a new engine i would go with the saito just because if you have no experience with YS's they are bit hard to get tuned right because the fuel system is problematic if everything isnt working 100 percent. I will probably fly more pattern with mine until i can build my ultrasport 60. or I may end up buying an aeroworks 60-90 size for 3D. I got my Seagull airframe for free at a swap meet.

I really like the 110, but I had one on a Mojo MoAss 60 and it really made it fly heavy, I switched back to the 100 and have a much better plane. I would have sworn that the Mojo wouldn't have noticed small wieght incress but IMHO it ruined the way the plane flew. It may not have mattered much if I didn't 3d.

Another down-side to the YS is the need to run fuel with at least 20% nitro. The Saitos will do just fine with 5%-10% and that makes for much cheaper flying.