90 sized engine recommendation
 

I need a new engine for my Big Stik 60. I'd like to go with a 90 sized two stroke but would consider a four stroke. Any recommendations? I'd like to spend less than $300.

Any thoughts of an OS 120AX? It's $10 less than the OS 95AX. If i'm going to spend the money on a 95AX, would the 120AX be a viable alternative? Tower says it has the same mounting dimensions as the old 91FX.

RE: 90 sized engine recommendation
 

I have a Super Tigre 90 on mine and it is a good match all around. Very reliable and plenty of power and costs much less as a bonus.
I like that I can count on this engine to be there all the time.:D

RE: 90 sized engine recommendation
 

You can get a Magnum .91 fs on RCU market place for under $150.00 new. Been flying Magnum 4 strokes for a few years now and they are very good engines . Best bang for the money.
ST .90 can be hard to set up , but once dialed in , run very good.
You really donthave to spend alot of moneyto geta good engine.

RE: 90 sized engine recommendation
 

I bought one each of the following, still haven't decided which one I'll use on my Stik 60:

http://www.hobbyking.com/hobbycity/s...e_Glow_Engine_

http://www.hobbyking.com/hobbycity/s...ke_Glow_Engine

RE: 90 sized engine recommendation
 

Right now Hobby People has the Magnum 91 4-stroke on sale for $139.

http://www.hobbypeople.net/gallery/210868.asp

Ken

RE: 90 sized engine recommendation
 

The 120Ax is a really sweet engine, but it has 60% more power than most .60's. Won't it be a little over the top?
Anyway, I have a 120AX and I start it by hand, usually by twisting the spinner backwards. This causes a kick forward and Brrrmmm, away she purrs.

RE: 90 sized engine recommendation
 

I have an OS 120AX, to much I think. I have 4-5 Magnum FS's (can't remember) really good and at the present prices hard to beat.
Jayhawk stated that he preferred a 2 stroke so I by passed the 4 strokes. My ST 90 took time to run in but after a gallon or so it is
really hard to beat all around.

RE: 90 sized engine recommendation
 

The 1.20AX is a sweet piece. Will you have ground clearance for a 17" prop? The 1.20 is going to need a 17x6 or 16x8. Don't over look the OS.75 AX. It is another nice one.

David

RE: 90 sized engine recommendation
 

The Supertiger is a good match for it. If you want a little more power, go with the AX. Either one will be good, but if you want a bigger one for later, get the 120, otherwise the 95 would be fine.

Don't make the FX mistake. They are crap and you will waste your money.

personally, would go with the 95 AX. I have run many engines on the stik and that would be a perfect combo for it.

RE: 90 sized engine recommendation
 

Kangke sells SK and JBA two stroke engines. Both brands are available in a 90/91 size, priced around $100.
http://www.kangkeusa.com/indexo.htm
I have read positive comments about SK but I do not think I've ever seen one.

RE: 90 sized engine recommendation
 

The SKs have been very good engines for me but I have only used the .91s so know nothing about any of the others they make. Not a high RPM engine but designed for torque and to throw a bigger prop. I have never seen or used one of there JBAs so?????????? When I have a choice I go four stroke though and have a couple of the OS .91s and love them. I also like pumpers but my .91s aren't pumped, no big deal, they run great as long as I do my part. I have found the YS 1.10s for as low as $325.00 though so you know what my first choice would be.:D

RE: 90 sized engine recommendation
 

Thanks for the replies. The Magnum and ASP four strokes sound interesting. Anyone know how realiable and easy to tune these two brands are? Will they run as well as an OS AX series two stroke? I really want to focus on the engine that will give me the least hassle. If the OS 120AX requires a 17 or 16 inch prop, that's going to be problematic for ground clearance, even with the tail dragger conversion i've done.

RE: 90 sized engine recommendation
 

Magnum and ASP is the same engines, that is, they come from the same factory, but have different names around the world(Magnum in U.S, SC in EU, and ASP in Asia).

They are often said to be much of the same quality as O.S engines. Actually some are better, since some O.S engines tend to peel a little bit on the metal inside the cylindre.

They are harder to tune though, they are very sensitive on the needles. But once you get the hang of it, it will run very well. Not a problem, even for a beginner. Just be careful, max 1/8 turn at a time, especially on the low-speed needle.

RE: 90 sized engine recommendation
 

I bought a new Magnum .91 fs a couple of weeks ago .This one has the crankcase vent , running back to the intake. I ran a gallon of Omega 10% very rich settings. After running a gallon thru it, I fueled it with Omega 15% and set the needle for flying. Like my other Magnums/ASP fourstrokes , it runs flawless . Unbelievable idle and top end and throttle transition is very good.
I use to fly only Saito but after a few years of Mangums/ASP I rarely look at Satios when I need a new engine.. Satios are great engines, but just like O.S are way over priced . Heck you can buy a shortblock , small block Chevy for what a these small highend 4 strokes cost. lol

RE: 90 sized engine recommendation
 

As stated by others here and elsewhere. Run a gallon of fuel through it before trying for all it's got, or forming an opinion of your new engine. With proper break-in, just about any engine will bring you years of joy. And don't rule out your original ST90. A gal of low nitro, 18-20% oil fuel will show what a great motor these are. As for your desire of a 4stroke, same advice. A gal of fuel before an honest opinion can be made (or more on some of my bigger 4 strokes).
-Snuts-

RE: 90 sized engine recommendation
 

Be very hard to beat the 1.20AX with any of the .91 four strokes. When tuning an engine there isn't any difference between a four stroke and a two stroke. You have a high end and a low end, with YS there is a regulator screw but it's almost never touched. About once a year I open up the rocker cover and check my valves. The four stroke throws a bigger prop and sounds cooler, gets a bit better fuel milage and runs less rpms. I haven't seen any chrome peeling in an OS engine sense they first came out with the .46FX, that was taken care of right away too. I run four strokes just because I like them, they have a smoother power band then a two stroke but it isn't any big deal. I am not a Magnum fan at all and have never gone out and bought a Saito brand new. On and off I end up with a Saito and they are great engines but I would rather have an OS or YS engine. It's just one of those pilot choices things. Only thing I like about Magnums is the price but I wouldn't buy one new, I have had several of them but git rid of them pretty quick.

RE: 90 sized engine recommendation
 

The OS 120 AX is way too much engine for your 6 1/2 lb. Big Stick 60! Besides that it loves to suck up fuel fast!

You won't get much speed out of a 91 4-stroke engine unless you use a smaller prop and run it full bore which will only shorten the life of the engine.

A Super Tigre .90 would give you unlimited vertical but it won't stay tuned as well as an O.S. engine will.

If it was mine I'd have an O.S. 75 AX on it and fly it like a bat out of H???!

big dan

RE: 90 sized engine recommendation
 

Too much power is just about right!:D Only reason I would ever say to run a 120 two stroke on a 60 size stick is because the plane can handle the power and the pilot has control of the sticks. Down the road the 1.20 engine will give you a lot more choices on a bigger plane or one that needs to go on a diet. The OP is also a mile high so some added power could be a good thing. If it was my plane I have an OS .91FS and a SK .91 not doing anything at the moment, both great choices for any 60 size plane when you live high in the hills. A lot does depend on where you live and fly, at sea level the 1.20 would be way over kill, at a mile high???

RE: 90 sized engine recommendation
 

Oh yeah, a 1.20 on a plane designed for a .60 will be great. At least until it's time to land and he has to go deadstick just to get it on the ground. It'll make balancing alot of fun too with all that extra weight in the tail.

All a sport plane really needs is enough horsepower to pull vertical reliably. Going up one size to a .75-.80 will do that for you without sacrificing other flying characteristics.

RE: 90 sized engine recommendation
 

Perhaps there is something about DENVER you don't quite understand.:eek:

RE: 90 sized engine recommendation
 

E.g. Altitude?

However I somewhat agree with him.

I have Big Stik .60's with both a SuperTigre .75 and a Tower Hobbies .75 two stroke engines.

Both give me unlimited vertical. ( Note however that I'm at about 350' above sea level however )

Given the altitude a slightly larger 2 stroker may be called for ( e.g. a .90?), but a 1.20 seems awfully large for this plane.

Even with my .75's I had to put a big 4800mAh pack in the rear of the fuse to get the plane to balance, and an even bigger engine might be problematic.

RE: 90 sized engine recommendation
 

What are your opinions of a 95ax vs 75ax in terms of engine design? Do you think that a 2 stroke in the 60-75 size is generally a more reliable design than a 2 stroke in the 90 size? It seems I've heard people having issues with the 91FX. I also had a SK90 and I never could get it to run just right. I'm wondering if 60size engines is just a general "sweet spot" for 2 strokes?

RE: 90 sized engine recommendation
 

The largest 2 stroke O.S. engine I have is the .75AX. I did not use that on the Big Stik, though the engine is very reliable.

I've found it much harder to deal with larger sized 2 strokers in terms of tuning, heating, etc.

So now that you mention it, I'm inclined to agree with you that there may be indeed a "sweet" spot for 2C engines in this range.

With larger 2C engines ( all non-OS so far ) I've typically had problems so I've ultimately gone with 4 strokers or gassers for engines above this range.

RE: 90 sized engine recommendation
 

Did your 75AX run better than your GMS .76? Is it worth the extra $120 for the O.S?

RE: 90 sized engine recommendation
 

I find that the O.S. AX engines practically start on the first flip or touch with a starter, without needing any initial adjustements.

A tweak or two after they have had a tank or two run through them and you are ready to fly.

With the Tower, SuperTigres, GMS, etc. I have to spend more time breaking the engine in and getting things tuned up. Each engine has their quirks, so you also have to in part learn how to deal with them.

Is it worth the extra $120.00?

For a beginner, DEFINITELY.

For someone who is familiar with engine tuning? Things may be different.

I find that I now own a large number of engines. A quantity I would not have been able to afford if they were all exclusively O.S.

So I found myself first purchasing an OS engine for each size range and type, then switching to another manufacturer to obtain cheaper engines.

e.g. My first non-problematic 2C was an O.S. .46AX, afterwards I started using engines from other manufactures in that range.

My first 4C engines were O.S. 91 FS and an O.S. 1.20 FS Pumped, and after becoming familiar with those I switch to Magnums and Saitos ( I really like the Saitos btw, as they are VERY forgiving on the tuning. ).


If OS engines were not so relatively expensive, as are their parts, I would have stuck with them exclusively.

However I've also been pretty happy with engines from other manufacturers, excepting the Evolution 1.00NX.

RE: 90 sized engine recommendation
 

I didn't catch that he was in Denver, which of course makes the engines less powerful. The problems with going too big are still there though. I have a .60 size stick that the former owner used a 100 Saito on. He said he couldn't get it to sit still at idle, couldn't land it without cutting the engine, and couldn't get it trimmed to fly right due to the weight and the torque issues. He had several wrecks that he blames on the big engine and wound up giving up on the plane.

RE: 90 sized engine recommendation
 

If you are a beginner then I recommend a .60 or .75 for a .60 sized sport trainer. A .91 four stroke would be good though. Power of a .60 but a bit better slow speed grunt.

RE: 90 sized engine recommendation
 

Get an O.S. Engine. You'll be glad you did.

If you want an engine that's harder to tune, get a brand other than OS.

If you want an engine that dead sticks on you in the air, get a brand other than OS.

If you want an engine that won't hold it's value if you ever want to sell it, get a brand other than OS.

If you want bad fuel economy, get a brand other than OS.

Just my 2 cents.

I really like it when I fire my OS engines up with 1 or 2 flicks of the prop and get my plane airborne and other are still fiddling on the ground trying to tune theirs with their cheap engines they have on them.

That's about like driving a rolls royce with a old beat up ford motor in it just cause you wanted to save money on the motor.

big dan

RE: 90 sized engine recommendation
 

S thunder tiger 91 2 stroke would give you the best bang for your buck, they have been compared to OS engines and although they have a slightly lower preformance spec, it isn't by much and the reliability is second to none, and as I said you can't beat the price

RE: 90 sized engine recommendation
 

Most dead sticks are caused by fuel line problems. O.S. is no more immune to this than any other brand.

I've over 34 non-os engines and there is no difference in the dead stick rates.

When I get a dead stick it is because of a fuel line problem, fuel depletion ( e.g. long downlines), mistuning, or as is usually the case that I'm merely let the tank get too low.

O.S. engines are more expensive up front to buy and more expensive to maintain because of the high cost of parts.
It is not that they "hold their value" better, but rather people seek more money when they go to sell them.

They get just as dirty as other engines, wear down at the same rate, etc.

Not that there is anything wrong with them.

I've purchased used O.S. engines then found that they were simply not worth renewing or repairing because of the high parts cost.

If you are getting different fuel economy, then you have a tuning problem. It has nothing to do with the brand name.

My OS .75AX burns exactly the same amount of fuel as my CHEAP Tower Hobbies .75 engine, and both pull the same plane in exactly the same manner.

The OS was MUCH easier to break in though. The T.H. didn't come into it's own until I had run about a gallon through it.

RE: 90 sized engine recommendation
 

The OS engines do seem to have better quality control and are designed well. They are the guaranteed performers. Other brands are trustworthy too though, even if there is the occasional one that needs some sealing done and takes a little more time to break in and get tuned right.

RE: 90 sized engine recommendation
 

None of his problems were the cause of the engine. These are 60 size planes I have built from kits or scratch. The Harley Extra 300 had the OS 1.20 FS but I went back to the YS 1.20, the yellow Extra is also another CG kit with a YS 1.40, the Hots is a midwest kit with a YS 1.10, the Daddy Rabbit is scratch and powered with the SK .91, it also flew with a SK 1.10, the 4*60 is powered with a Saito 100, the blue Extra 260 is running a SK 1.10 but went back to the .91 when I had to return the engine.
The Boeing bipe is scratch and had a OS 1.20 in it for years, I changed it out for a Brisn 40cc gas engine. None of them roll out or have any trouble with landing and all trim perfect. Low idle or tension on the wheels keeps them from rolling out. Building straight keeps the plane from doing odd things in the air that you can't trim out. The Boeing bipe is a giant though with a 68 inch wing, the 1.20 flew it but was really lacking when you wanted to show off and stunt it.

RE: 90 sized engine recommendation
 

the ST .90 is a great engine and is NOT hard to tune .

Hell i didn't even know that Denver still allowed fossils to be burned for a mere hobby :D

RE: 90 sized engine recommendation
 

Ditto on the ST-90...;)

I've had many, both G's and K's but I prefer the K model when I can find one, the G model is the replacement.

I use 15% Powermaster with a OS-F plug.

RE: 90 sized engine recommendation
 

I have the 60 size stik with the Super Tigre 90 even at this altitude it is great! I also turned it into a tail dragger! Every one needs to have just one of these in the hangar!

RE: 90 sized engine recommendation
 

Good points from both Carlos and Dan. I have been doing this for a few years now and the only Brand X :eek:engine I ever couldn't tune well were the MDS engines. Then it hit me, they were made for FAI fuel!!!! The engines ran better then but the castings were still crap and tended to break. If buying used though, here it comes, I only buy OS!!! I also only buy four strokes. I would also buy YS but you never seem to run into anyone selling them very often??? Why would that be???;)

RE: 90 sized engine recommendation
 

Grey beard , there are quite a few YS on the RCU market place , if your looking for used one,s and lots of OS too. Seems to be more as we get farther into winter , or picking up extra cash for X-mas?
I check it several times a day for kits, but can not resit looking at the 4s goodies.lol

RE: 90 sized engine recommendation
 

Thanks but I never buy on line, if I can't see it and check it out then I stay away. I like to go to club auctions, pretty good stuff and not much money!! I haven't done well finding engines but I have made a killing on kits! Like I'm the last builder left in the world or something, no one bids on them?

RE: 90 sized engine recommendation
 

O.S. 91 2 stroke would be my reccomendation. I've had about a half dozen of them and they have all ran perfect! Starts easily by hand. Turns a XOAR 14 x 8 at well over 10k

RE: 90 sized engine recommendation
 

Don't be afraid to buy here on RCU, 99% of our people are very trustworthy.
I used to buy and sell all the time for many years but for the last few I've gotten back into hot rods.

I never buy from a new member, some one with just a few posts to their name has no track record and could be a poacher.

I've never been burned and have never been asked for a refund, I've been disappointed a couple of times but that was my fault for not asking the right questions, communication is important and if you can talk to the seller even better.