ameyam

Hope I dont open a can of worms here. I have used OS engines all through since I started flying in 2007. Since then I have lost 3 55ax and one 75ax, through reasons other than crashes. The very first one had the conn rod on the crank shatter and send debris through the engine in flight. The second and third lose compression once they reach operating temperature, likewise the 75ax.

Now I am in the sudden position of not having a usable engine in the 50 and 70 size- the smallest engine I have running is a FS91. I have a 72a in stock but It is not worth to use that on a trainer or similarly sized airplane.

Now, tower sells other engine makes- Magnum, Super Tigre (I think people call it ST for short) and Thunder Tiger.
1) How are these engines? They are half the price of the comparable OS.
2) ST even has a 61 sized ringed engines and I am told the ringed engine will always give more power than the ABN engines.
3) I am also told that Magnum is rebranded ASP (if so I can also get ASP locally for much cheaper) and that the quality is hit and miss

Can you guys clear this issue for me?

Ameyam

stevenmax50

My Feedback: (1)

I have flown many Magnum engines.  And I have yet to have a problem with any of them.  Hobby people had a sale on the magnum 91 4 stroke.  It was priced so low I bought one without even having a model to put it on.  I just know someday I will.  The 1 OS motor I owned seemed to never idle correctly.  So 3-4 years of flying and I can recommend Magnum with no problem. 

jrcaster

If you are losing compression, you may be running them too lean. Magnum and ASP are I beleive are the same engine(Magnum in US and ASP in european market.)

Another thing is if you changed what fuel you are using. Some fuels don't have enough oil in the mix for the engines. You can add a few ounces of Castor oil to help keep them cool.

oldtyme

I have used OS since I started flying in the early 80's and the older ones were fine. I am now of the opinion that OS is becoming hit and miss. I have started to buy Magnum and so far so good. The one thing that really stands out about Magnum is that the cylinder liner is real chrome not Nickel. I have had several nickel liners on OS's peel. I also like the price of the Magnums and I've heard that they are just OS spin-off's. I also know that some of the guys at our field are using Thunder Tiger's and really like them.........only thing is that they too have nickel liners. I'm sticking with Magnum for now ....I all of a sudden own 5.............2 4-strokes and 3 2-strokes.

Film at 11,
Cheers,
Andy

Gray Beard

My Feedback: (-1)

I will go along with this 100%, everything sounds like a lean run, over heating or not enough oil. If you are having a problem with OS you may really have problems with other brands.
I don't use the smaller two stroke engines any longer but I have been using the SK brand that is sold through Kangke or SuperKraft in there .90 size. I have been using them for several years and gotten others to give them a try. They run perfectly and so far I haven't ever had a dead stick with any of them.
I did get one with a bad crank pin and it broke off in flight. I sent it in to service and it was repaired and returned in two weeks. It was repaired because they had a batch come in with bad cranks so they just installed a new crank and rod instead of sending me a new engine. Two years later and it's stil running great. $100.00 and comes with a muffler!
However even an SK can't stand being run too lean or over heated, until you have that little problem figured out you will always have problems.

Charlie P.

I like my TT Pro-46.  Haven't tried larger Thunder Tiger engines.  I also have one of the SK .50 (Kangke) and had troubles getting it reliable with the stock carb.  Switched it out for a Perry and it's been fine since.  Currently putting it into a new airframe (Tower Razor 3D).

Had one of the Chinese Super Tigre .51 engines and it ran great.  That one sufferred a high speed ground strike (no fault of the engine) that cracked and broke the caseing.

jester_s1

I have an OS .46 and a TT 46 and I can't tell any difference at all in the two. My two Magnums aren't quite as good, as in they don't idle quite as low and are more touchy on tuning and a bit less powerful, but they are serviceable engines. My one ST has the typical rich midrange issue that I just haven't ever gotten around to fixing, but it is also reliable and makes good horsepower. OS makes a good product no doubt and they service their product better than most. If you have problems with them consistently I'd agree there's probably an issue with the operator or the fuel instead of the engine. But for my money the Thunder Tigers are the best buy in the hobby today. 99% of the quality and 70% of the price.

52larry52

My Feedback: (1)

I agree with GB that it seams to be a lean run condition that is damaging your engines. I have 21 or so O.S. engines in service, in planes, and have had (knock on wood) no failure issues with any of them. I have FP, LA, FX, & AX in assorted sizes .25 to 1.60 and they are all reliable and EZ to tune. Now, I also have 4 Super Tiger engines in service and have also had no failures but they are harder to tune but make lot of power for thier size. If you are not comfortable tuning, stay away from Super Tigers. I have also found that Super Tigers also must be fully warmed up before take off. I also have 1 Thunder Tiger Pro 46 and it is like an O.S. at half the price....reliable, EZ to tune and very user friendly. I like it. When tuning an engine by ear prior to take off I will peak the RPM at full throttle turning the needle valve in a lean direction till it peaks then turn back the needle valve in a rich direction 1/4 to 1/2 a turn, rechecking that I still have good transition from idle to full throttle. it's good to have the engine "warmed up" at this point so it won't lean out more in flight and go dead stick or run lean and overheat, damaging the engine. This is just how I do it, everyone has thier own way, but this works for me and I hope it will help you to. That half a turn in the rich direction will cost a few RPM but will not cost you an engine.

Gray Beard

My Feedback: (-1)

Ameyam has a history of not being ale to tune an engine if you want to go back and read his old posts. It's also a lack of understanding and a big lack of any help from a decent instructor. Most of us have had the pleasure of being taught by an instructor with many years of experience and having everything from local hobby shops and good store bought fuel too, something else lacking in India. We don't have a clue as to what type of fuel was being used in his engines either. As I recall he was mixing up a home brew? It's been a while and I don't recall. I do recall people trying to explain air flow to him.
All in all maybe a cheaper engine would be a better idea. The TT Pro series is every bit as good as OS, just an opinion, but we used to have a racing class with nothing but them for power. Never any engines failures. I just think Ameyam will have problems with any brand he buys until he finds a good mentor to teach proper engine operation and set up aqnd runs a good fuel through them.

acdii

I have an OS 52 and a Magnum 52. Both are good running engines. The Magnum is still new, so intentionaly  running it rich on the low end, but overall a good running engine

ameyam

Hi GB

I got over the tuning problems. I can tune them quite OK now, Not 100% as some of the more experienced members but close enough so they dont cut out and I keep them on the rich side. With regards to fuel, I am using Klotz 100 for the last year or so, its got 20% castor blended at the factory. Home brew, yes, just 20% klotz, 5% nitro and methanol. Earlier I had my mentor brew the batch for me but since he isint keeping well for some time, I started making the batch. I started with no nitro initially and found the engines impossible to tune by ear. My only running engine was a FS91SII then and with no nitro I couldnt hear the pitch change, so I began to use 5%. 20% oil and 5% nitro is still conservative, some guys are using 15% oil and 10% nitro

All these engines (ones losing compression) are from January last year (I started observing them lose compression then) when I had just started to learn to tune my engines but the damage was most probably done well before that. The first 55ax had already done major amount of flying so when it lost the crank end, no one was surprised. On the second 55ax, after I had a crash at takeoff, I gave the airplane for repair (those days I didnt have the building experience). When I went to collect the airplane, I found the engine sitting in a caddy with screws, bolts etc. That was when I noticed the piston was scored on the side. Dont know how that happened but it never ran properly afterwards. The 75ax was never run in properly, again I didnt know anything about engine tuning etc then and needed others to tune it for me. Another point is all these engines came from the same batch and others who got their engines from the same batch also had similar problems. So its partly operator and may be a manufacturer issue

Subsequently, I never bought engines from that shop. The FS91 I got from Tower and it has only one deadstick in 2 years of flight, entirely tuned by me. I note that there are some ancient (10 or 15 year old) engines still operating but very few from 4-5 years back at my field. So OS must have dropped quality somewhere


Ameyam

jrcaster

If you have two 55AX's, you may be able to use the one with the bad crank for parts to repair the second one with the scored cylinder. Make sure you use the same piston/sleeve in the second engine, and in the same orientation (mark the top of the piston as to which side goes to the front.

And if I remember right, ABN (aluminum/brass/nickle) engines are more sensitive to lean runs than ABC (aluminum/brass/crome). That will show up as peeling.

Since it has been mentioned that you mix your own fuel, one thing you have to be carefull about is moisture. If you get any moisture in the fuel, like from a batch of old methanol then you will have more problems that will show up as a difficult time of tuning your engines. Since we as an end user do not have anyway to reliably measure the moisture contents, it is a better idea to pay the expensive prices of the commercially botteled fuels, also try to buy fresh fuel. If you notice a hobby shop that has had that bottle of fuel on the shelf for a year or two, buy from someone else.

ameyam

In my country, the chemical shops do not sell methanol direct to just anyone. Nor do they offer any assurance that the methanol is not hydrolysed (meaning its free of moisture). To buy methanol, you need to have a college lab license or be using it on an industrial level. The way we arrange methanol is the former- my mentor teaches aeromodelling at a college ant they buy in bulk at beginning of season, then share as they go along. Thus everyone used the same methanol base. Commercial fuel just isint available. Unlike abroad, aeromodelling is a niche hobby, so you are basically on your own regarding fuel.

Same problem with gas- the petrol pump will not sell you gas in a can. You need to pump it out of your car gas tank. But atleast its more easily available than methanol. Problem really is you cant put a 20 cc engine or even a FS91 on a trainer and I can fly the larger airplanes in the monsoon

Ameyam

jester_s1

Can't buy gasoline in a can? I guess there aren't a lot of lawns in India eh?

Two thing I'm noticing that would have helped you and will continue to help you in the future. First, if you will mix your fuel by weight instead of volume you'll get a more accurate mix. As the fluids expand with heat the ratios will change by volume, but will always stay the same by weight. The second is to use a tachometer. Tuning by ear is easy enough once you know how to do it, but the tach takes all the guess work out of it. Kudos to you for pushing through and doing this hobby even though there isn't a big local community to support you. Hopefully there will be more RC pilots eventually and you will be there to help others with what you've learned.

mike31

My Feedback: (67)

Super Tigre engines have been my choice for years. Massive cranks and the seem to run forever. Less nitro requierd as well. 5-10 percent.

ameyam

Yes, few lawns and even few backyards. The local laws say there should be a 6M minimum setback between buildings and their compound walls. The idea is to allow for the fire tender to move in. Very few buildings even have space to park a small car.

So then, if I get a good deal I should pickup Magnum / ST etc?

Ameyam

Gray Beard

My Feedback: (-1)

First thing, Fuel, listen to Jester about mixing your own, I see a big problem though, getting a good scale that will measure the weight perfectly.
These were used engines?? If so my guess would be damage done by the original owner.
We once spoke of the heat there in India and the monsoons. You stop flying during monsoon season and it gets humid. You may want to remove the back plate and glow plug before you store your engines, flush them with straight alcohol, let it evaporate completely then use some after run oil of some type before storage.
As for a cheap new engine then I would go with the TT PRO series engine. I think they are as good as the OS but less then half the price. I think Tower is still selling them. You may have problems with the STs and magnums right out of the box and it's too hard for you to return them if there is a problem.
It's very hard for us to even think about how hard it is to be a modeler in another country. I have friends in Canada that have to mail order everything too depending where it is they live. India isn't just another country to us, it's another world.
Good luck, I think you will do well with the PROs.

eddieC

My Feedback: (2)

As Grey Beard said, these were most likely operator-induced failure. I've never in 40+ years in the hobby heard of a 'bad batch' from OS. I have OS engines that are 25+ years old. If taken care of properly, your engine, no matter the maker, should easily last 5-10 years.

TT and Magnum are very capable motors.

ratshooter

Ameyam I have magnums, super tigre, thunder tiger and os engines. In the past the os engines were hands down the best. easy to start and just ran forever it seemed. I got out of rc 10 years ago and got back in a year and half ago. My first new engine was a magnum 52. It threw the rod on the third tank of fuel. It took a month to get a replacement. I also bought a magnum 25 when they were on sale. Both engines are still new in the box. I don't have planes to put them on at this time. I am sure my first 52 blowing up was a fluke. The 52 FS Magnum I had ran well but didn't seem as powerful as the OS version. I had it on a hanger 9 Cub and it always felt underpowered. there was no comfortable margin of power if you needed it.

I also bought a ST 40 ringed engine a few months ago. I could not start it without an electric starter. Now that its broke in it will hand start sometimes. I got a deal on it until I had to buy a $30 starter to get it going. Its an OK engine. It should last a long time.

I have a TT 46 pro on a big stik 40. It hand started the second flip of the prop. Its my best engine. It runs as well as any OS I have ever owned. I have owned several TT engines over the years and everyone has been just perfect. That would be my recommendation to you for brand to choose from.

I have a new OS LA 46 that was a real bugger to start when brand new. I had to use the electric starter on it. Then all the screws stretched and I lost compression. I had to remove the engine to locktite all the screws and that fixed that problem. Its not as powerful as the old FP 40s I used to own. I believe the OS engines may not be as good as they once were. I sure did like my FS 46 engines and wish had them back.

ameyam

Well, those werent used engines. The people who set them up for me just werent particular. Anyway, I passed on one of the 55AXes to another modeller who felt he could use it but then found out he couldnt. I just gave him the engine, so we are still on good terms. The other (the one with the scored piston, picture attached), I overhauled and there didnt seem to be anything majorly wrong so I put it back together but it still doesnt run reliably. Couple of weeks back on a trainer, I got 5 minutes of flight before it cut (it had deadsticked several times on the ground already). These two 55AXes are pretty much expired unless we get replacement piston-liners.

The 75ax, I have recently overhauled and found it was completely clean (pictures of the piston, liner and bearings attached). It looks very much brand new doesnt it? Since then, we have run half a tank through, need to run it properly still to 'certify' as reliable.

In the meantime I just got a 46ax used. The owner hadnt even finished running it in properly. He moved on to electrics and this was in storage for some time- really gunked out internally. I cleaned it out thoroughly after complete dis-assembly, then reassembled it. Queer thing about this one is that even without the plug installed, its very tight at TDC, nearly locking up there. Never experienced that with any other engine. Just gave it a run at idle for a couple of minutes, runs fine though.

If the 46 is usable and the 75 is not, we will get replacement piston-liners for my 75 and the 55 I gave to the fellow flier

Thanks for the storage advice GrayBeard. I usually wash my engines with fuel before the monsoon, drain and then put in plenty of 3-in-one oil (light machine oil / sewing machine oil), then put in plastic bags and then seal in the original box with clear tape. Thats the same way the engine come from factory (minus the sealing part), serves the engine well. All the aeromodellers here do the same (we have to mail order everything, even after-run oil. Machine oil is a good replacement). By the way, we do usually stop flying in the monsoon, but not totally. Usually June and July are un-flyable whereas in August and September we can fly between showers. This year has been different as there is a 20% lower rainfall (which is very bad for the economy). Therefore the 75ax and 46ax are still outside (FS91 and DLE20 are in sealed storage). I usually do keep some oil in the engines when they are not used for a couple of weeks, it burns off when I run the engine the next time.

Ameyam

eddieC

My Feedback: (2)

We've had issues with 55AX deadsticking here. Do a search, there are a couple threads on this engine. We used a couple things from those threads: Remove the baffle in the muffler (cone-shaped item), and use an OS Type-F (four-stroke) plug. They also seem to take twice as long as other similar engines to fully break-in but, after at least a half-gallon through them, they start to really become as reliable as others.

They are also sensitive to the low-speed needle, so make sure the LS is not rich throughout the break-in.

jrcaster

Wow, you have to be dedicated to go through so much to stay in this hobby.

As far as your original question, any brand out there has their good engines as well as their lemons. OS is no exception.

Since you have to mix your own fuel and have no way to verify the quality of your components, instead of clicking airplanes forum on the home page, click on the forums button and after the long list of all the forums show up, scroll down to (Glow Engines, Gas Engines, Fuel and Manufacturer support.) You may be able to figure out how to tell when you have a bad batch of fuel.

I have also read that MVVS engines run good on 0% nitro methane or FAI fuel if that would make life easier for you.

Charlie P.

Ithink he was referring to the need to buy gasoline in small quantities for lawnmowers - one or two gallons (four or five liters)at a time - by refilling storage cans.

jaka

Hi!
The simple fact is that all engines today are good!
You can choose whatever engine you like and the will all give very good performance and hold up for decades if properly handled.
They also need no modifications to run right and no long running in (if they are ABN,ABC or AAC engines). All of these engines will run and throttle just perfect from the moment you start the engine! - If not you haven't done your homework (see below)

As long as you use the right fuel, glowplug, keep your engine clean, use the correct prop size, mount the tank according to the tank mounting rule and set the engine right (by ear)...everything will just be fine! If it will not run well, you yourself are to blame! Sorry! But too many blame the engine manufacturer when something doesn't work right.

ameyam

Good point regarding the tank height Jaka. On the 75ax, the airplane it was mounted on first was a Phoenix Topstar 60 -same as UCD 60 and has the same problems probably. I think the tank was too high, so with the engine inverted, it would lean after half tank. Later with the FS91 on the same airplane, I lowered the tank and never had problems subsequently. Dont know whether that did something to the 75 but last year I did mount in on a Reactor 46 and just like the 55ax before it, it would run, tune, overheat and deadstick

Like I said, before trying my luck with new engines, I will try to resurrect the 75. It opens a lot of possibilities with the various airplanes I have NIB

Ameyam