I have a gms 47 and I haven't had any problems with it. Maybe you got a lemon, talk to GMS about a replacement.

<span style="font-family: 'Gill Sans'; font-size: medium; "><div style="background-color: rgb(255, 255, 255); padding-top: 5px; padding-right: 5px; padding-bottom: 5px; padding-left: 5px; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font-family: Arial, Verdana, sans-serif; font-size: 12px; ">Well, I wasn't happy with my knock off, that's for sure.  Next time it's gonna be a DA for me. Gas motors are a whole different bag compared to the glow motors... lots of weird stuff that isn't very good floating around out there.  I've seen galling  (heat welding) between ports and mufflers, cracks in cases,  bad rings, defective ignitions,  bad carb designs, you name it.  A LOT more to go wrong on a gas motor, compared to a simple glow motor. You definitely will get what you pay for with gas motors,  from my experience anyway.</div></span>

If an engine runs fine on the ground but dead sticks in the air, it's usually a problem with the plumbing rather than the engine itself. A thorough check of the fuel tank, clunk, clunk line, and fuel lines is in order. Check for splits or cracks in the various pieces of fuel tubing. Your frustration will only continue when you replace your "garbage" GMS .47 with a .46 AX at twice the the price and it does the same thing in the air that your GMS .47 did.

I've owned the GMS .47 and thought it was a wonderful engine, although I stuck with the front mounted needle valve. I haven't had a lot of luck with remote needle valves, I'd rather just be careful when I make my adjustments. Remote needle valves are just one more thing that can go wrong. I did find that my GMS .47 had more of a tendancy for having cylinder head and backplate bolts work loose; this does need to be checked regularly.

As for O.S. Max engines, I've owned several and I've always been happy with their performance. I've never bought a new-in-the-box O.S. Max engine, however, as I couldn't stomach the ridiculous price. I owned the .46 FXi that came on my Nexstar, I bought another .46 FXi new for $78 that was pulled from a new Nexstar, and I bought a GP Easy Sport for $125 with a .46 FX on the nose and 4 Futaba S3003 servos in it.

I still have the old .46 FX, although it's currently loaned out to a buddy of mine. I've sold off my two .46 FXi engines simply because I wanted to thin out my two-strokes and the O.S. Max engines would bring the highest resale value. I'm quite happy flying less expensive brands of engines. O.S. Max makes a good product, and I don't begrudge anybody for choosing to spend a little extra to buy the engine they want. I just get annoyed when I hear pilots advising folks to only buy O.S. engines because everone else makes junk. There are lots of great choices out there.

Ditto Biged.  I had a K&amp;B 65 sportster back in the late 80's.  Everyone at that club (near dallas Tx) told me K&amp;B sucked but they couldnt believe how well mine ran. 

I also have a GMS 47 and love it. I have a bunch of OS engines and love them, too. I even have two Super Tigres that I am quite fond of, and an Evolution that has never let me down. My first Magnum (.91 Four Stroke) is on order from HP, and I hope to love that one just as much. I know I love the $139 sale price.

Yet another thought on the GMS.47: I just replaced the .52 two stroke Magnum on one of my heavier sport planes with my GMS .47 (the Kaos that it lived in is down for repairs....) because the .47 can fly a 7.5 pound airplane just fine for sport with a 10-6 prop. While the .52 really churns  a 10-6 APC fast, over 15,000 on the deck, I need it's extra weight in the nose of another plane. How often can you feel OK about REDUCING the size of your engine?!  Another nice thing about the GMS .47 is that by being bored out, it's lighter than a comparable .40.45. or .46.  I look forward to buying another GMS, or Magnum motor in the future (if I can ever survive this "new economy", right?).

Eh, if it is garbage PLEASE send it to me.

I'll take it off your hands!


I second BigMustafa's comments...

... And ( knocks on wood ) I haven't had problems with the remote needle, though I periodically check the tightness, fittings and also replaced the tubing. I also use filters on my engines.

I'll trade a used Evolution 1.00 NX for an equally used or unused GMS 1.20 anyday.

All of my Tower Hobbies engines run very well after break-in too.

I would get rid of the 100 NX also, reason being it has been discontinued and there are very few parts available for it. I have a wanted add for a friend of mine that is looking for a used 100 NX he needs to use for parts.
jerrysu29 Call Sign Wild Man

8000 HP? What A/C? The Herc engines are 4300 HP each. http://www.angelfire.com/pa3/cadet98.../hercules.html

Maybe you add two Hercules engines, and subtract a Prat and Whitney R1340 to get 8000 ponies<font face="arial, sans-serif"><span style="font-size: small;">, but that only works if you stick a screw driver in it.</span></font>

I have had a couple of lemons. One was an OS .46 fx always stalled in flight. Went through the same thing as hercdoc. Everyone thought I didn't now how to tune it, but funny thing was, no one else could either. But I will still swear by OS engines. The second was a thunder tigre .40 I, or any one else could not get it to transition right. Then I had An OS .40 FP same deal but " Like everyone else said " let me try it
Once again it was broke down and inspected as well as the fuel system. Low and behold my good buddy dick said "hey, here is the problem," a little micro hair was stuck in the high end needle seat, He was inspecting it with a magnifying glass. We pulled it out with some micro tweezers. Engine ran great after. We could not figure out how the hair stayed after several cleanings but it must have. I have always wondered if that wasn't the problem with those other engines.

I use alightedmagnifying glass and have found small slivers of brass or some thing foreignmaterialin carbs ,that I would have missed with out it.

I don't fly the smaller engines but I did try out the SK .91s and so far have been very impressed, real stump pullers. I got to fool with one of the DLE 55cc gassers today, yes it is a knock off of the DA from what I could tell. I was really impressed with it and some places are really selling them cheap. If you have a problem and need service, well?????
Back in 04 when this was posted a couple of the kids in my club bought the new tower engines, everyone one of them had the air leak in the carb problem, doesn't sound like it has been fixed yet either??

What they said. I've found lint, hair, ghost turds, dirt and all sorts of stocking stuffers inside various carbs in the past when my engines were giving me fits. This is in spite of running a filter on my fuel jug and an inline filter before the carb. Somehow, that stuff still sneaks its way in there over time. Once, I had a brand new ST that I could absolutely not get adjusted right and ran unpredictable. Later that day after getting home, I yanked the carb apart and found aluminum shavings from the machining process inside the barrel. And this was one of the older Italian made versions, so I don't necessarily buy into that crap that the Chinese versions are any worse than the European ones.

Certainly, no one can logically deny the possibility of a tiny (or otherwise) foreign object, or a micro sized air leak, messing up the operation of any brand of motor, regardless of cost, or brand reputation.  Give a Gremlin a screwdriver, anything is possible....  <div>I was looking in the needle of my 80,000+ HP C-130 turboprop, and found a goose, two ground squirrels, three Old English 800 bottles, and a screwdriver.</div>

I bought a giant scale filter 20+ years ago for the fuel jug and have had to clean it just a couples times in all those years. The more clogged and matted it gets with fine hairs, etc., the better of a filter it becomes. I draw fuel directly out with a 2 oz or 5 oz monoject syringe and almost never have dirty fuel issues, not even with the tiny .049 engines.
GMS must have improved their quality recently, I've heard way more good than bad about them. I bought a .25 years ago and it seemed well made except it didn't have any "pop!" when you flipped it and it didn't have as much power as it's competitors. But it always ran.

Who is GMS ?

They are either made by or distributed by http://www.mecoa.com/gms/index.htm

I believe they are made by Sanye Machinery in Taiwan along with ASP, AP, Magnum, and SC. No doubt there are other house brands sold in other markets.

Very true, I can't see a lot of difference in the CNC machines used in China or Japan. I have been told the metals used are different but haven't seen it as a problem. Quality control may be better in Japan??? As Jug pointed out, crud can happen no mater who makes the engine. I don't see a lot of the GMS or Tower engines at the field these days so can't say if they have gotten better or not, other then that run on problem the Tower engines ran very well but if you stuck a finger over the carb and it kept runing you knew there was a leak someplace. A very old post but it seems to have found new life!!

i run two gms engines (.47 and .32) and tune/fly a tower .46 on a fellow club members' trainer (im his instructor)
all of the engines run very well (best .40 sized engine for the money, by far). what i have found is you need to set the hs a little richer then os engines (.25-.5 of a turn from peak) while os engines like 3-5 clicks.
the idle isnt hard to adjust, asumbing the engine has some time on it (half a gallon at least)
the tower has about .5 of a gallon through it and idles much better than id did but it is far from perfect.
the idle also needs adjusting all the time when first breaking in, if you want a prefect transition. the reason being the engines are rather tight when new and idleing doesnt create enough heat to expand the sleeve as much as it needs to, putting a bigger load on the engine...killing it.
as the engine breaks in the tight ness starts to go away and now the engine doesnt need as much fuel to idle (because the load on the engine has decreased), so its flooding.

my recommendation is to tune the idle as best you can
one way to do this is, start engine go to full power, rishen half turn from peak (let it stay their for a 30 seconds or so to let the engine heat up), go the idle let it sit for 15 or so sec, then go to WOT (wide open throttle) asap. if the engine bogs down then its to rich, if it pauses then continues, its to lean. sometimes a overly rich idle will cause the engine to die when it goes to WOT. another way to tune a engine is follow the above advice, if the engine still dies, lean it, if the idleing gets better, lean it more, if it gets worse richen it.
use the "if turning the needle this way doesnt work, then turn it the other way, if that doesnt work turn it the other way a lot " idea.
then fly the engine (stay close)
fly it around half throttle, just at the point where it doesnt load up from the rich idle.

give the engine a good gallon of fuel to let it break in, it should run fine.
the patience man will get a good running engine.
i had a mag 52 that was having this problem. put it on a plane that i could fly blindfolded and fought with it for a day, now it runs fine.

have u tried a different carb on it...im sure thats the problem

Agreed

Its called brand management. What those people don't realize that in all aspects of consumer goods... some company makes a product and sells it under different labels. Product A is cheaper than Product B and probably came off the assembly line together! Take a little effort and research out what is truly a cheap knock off and what is just a non-brand label.

GMS Engines are made in Mainland China. The exclusive distributor for North America is Great Planes Model Manufacturing:

http://www.bestrc.com/gms/index.html