Papa_John

I need to purchase a .90 size engine and the cash is tight. I was looking at a GMS and since I know nothing about that engine can somebody please give me a heads up on buying one. It's going in a CG Ultimate Bipe that will be used for sport flying not 3D

Thanks

ckangaroo70

My Feedback: (51)

GMS are So So
A Super Tigre G90 would be a better choice, and the price is right as well. I would spring for an aftermarket exaust because the ST's is quite bulky, and has a tendency to loosen.

XTOL

For what its worth I have a GMS 47 in an old Sig Kougar and it has run
nearly perfect since day one. Not a bit of trouble and it hauls the
old Kougar around with authority. I would not hesitate to buy another.

Mike Hammer

exeter_acres

My Feedback: (2)

My only experience is helping a buddy tune his....

it was a GMS 1.2

dead stick after dead stick after dead stick.... it is in a box with something like "return to sender" on it

britbrat

My GMS .47 is no longer with me. My GMS .76 is still there, but what a pain in the tail -- can't hold a tune any better than Kris Kristofferson.

Papa_John

LOL......very descriptive but not too kind to Mr. K (but it is the truth) Not sounding good for GMS so far.

ckangaroo70

My Feedback: (51)

I have seen XTOL's gms 47 run, and his does run pretty nice, but he is our clubs engine guru, so we always expect whatever he has mounted to run good.
For everyone else without the magic touch, or without a touch of luck like me, I found my GMS .40 a little stubborn to tune, so I did what I do to all engines that don't cooperate, I got rid of it! I also got rid of two awful Tower .46 Engines made by GMS for Tower. I have heard of less troubles with the GMS 47 than with the Tower 46, so there performance/quality seems to change among various GMS Engines . I have never owned the GMS 90, so it may in fact be a better engine than the 40 I bought. I just wouldn't want to waste my money finding out, when I do know that the Super Tigre 90 ran pretty good for me, and seemed fairly easy to tune, and keep in tune. Experiences may vary though!

Papa_John

I don't think GMS offers a .90 thats what it calls for, but I was looking at the 120......could be wrong

Tom Nied

My GMS 47 runs great.

RC-Captain

MAN... JUST GET AN OS ENGINE FOR YOUR PRIZE POSSESION. i THOUGHT OF BUYING A GMS FOR THE PRICE BUT WOULD NEVER PUT IT IN A NEW PLANE . THE TRAINER WOULD BE THE ENGINES FIRST TEST.

Mods-R-Me

My Feedback: (1)

Get an Evo 1.00 NX. More Power, same size, and just $169.00. Just got one and it is fantastic. On the other hand, my GMS 1.2 never runs right. It's evil I tell you. EVIL![:@]

APIA

If you know HOW TO TUNE an engine, the GMS line is very good. Most people bad mouth GMS as they are spoiled with OS engines. I recently picked up a black head (old) GMS .47 that was given to me by an OS guru and the thing pulls stumps if tuned correctly. It took me around 15 minutes to retune and the thing is scary.
-Tom

britbrat

That's just a little bit arrogant Tom -- I suspect that more than a few folks here could give you PHD tuning lessons.

There are tuning tricks & tweaks to be sure, including minor surgery -- but there is also junk. A very good place to start looking for junk is stuck right on the front of a GMS engine. You shouldn't have to resort to surgery to fix the carb in a new engine. Even after the surgical fix, it will be modified junk, with a limited lifetime before you need another carb or even more radical repairs to the existing one. Some GMS carbs are reasonably OK, which is where the lucky folks that get one think that GMS makes great engines. However, too many examples have porous castings, non-cylindrical throttle bores &/or tapered throttle rotors & misaligned fuel-inlet ports on the NV.

Then you can have a look inside -- I've seen these "gems" with lapping paste still inside the engine -- guess what that does for its lifetime.

The only thing scary about a GMS is the wildly variable quality of the "finished" product.

smosher9

My Feedback: (2)

I have 2 GMS's a 40 and 47. the idle mix is very touchy to set, differences in 1/16 of a turn can make a big difference. Set the high end 1st with a tach, then adjust the idle speed to @ 2300 rpm, check the transition and adjust low end mix slowly. with every tweak of the low end mix, go back and readjust the high speed mix. using a tach helps alot. I set the high speed mix to peak - 500 rpm. I use CP 10% and on the 40 engine with a 11x6 prop I get 11500 pk.

once tuned they run very well with lots of power, haven't had a dead stick once on either engine. With the change of weather here in New england I had to adjust the high speed mix but other than that haven't touched the settings.

Steve

Tom Nied

I don't know, but I have to agree with Apia (Tom) & smosher9. I have two GMS 47's, one I have on a trainer, and it runs fine, right from my test stand running to on the plane. I do usually open up a new motor searching for metal flakes, tightening screws. And the the other looks just as good. Mine didn't need any "surgery", just a little tinkering with the tune, but mine hauls just fine. Hey,,, go ahead, buy the overpriced OS. I still like using good sound tuning techniques to get all my motors to run correctly. But then again, I like the TT GP42. I'm sure I'd like OS as well.

APIA

Sorry for the "arrogance" britbrat, I'm sure that there are a whole lot of folks that could enlighten me in the art of engine tuning. I do not claim to be an expert engine tuner. I do understand the physics of how a carburetor operates, which simplifies the process... The GMS that I got did not need any surgury, just good old fashioned patience and some tuning know how. I am not here to bash OS engines, they are a fine product that are super easy to tune. I currently have a dozen or so laying around, I also have K&B, MDS, and ASP's that I got that could not be tuned and they all run perfectly. I am also the type that is strictly a kit builder. What good is this hobby if there is no challenge.
(By the way, I DO have a PHD in common sense, from the school of hard knocks)
-Tom

Norm Nestie

Had 2 GMS 47's and wouldn't trust a Goldberg Ultimate or any plane to the maddeningly unpredictable nature of the GMS engines that I HAD. Not a lot more $ for a Thunder Tiger or Super Tiger. Invest the extra cash now on a good motor and you will never regret it. IMHO

rustleruss

My Feedback: (3)

There is nothing bad about a GMS engine that a little loveing care would not fix like not driveing it into the ground and think its made of steel or not keep it clean or not break it in right or not tune it correct in the first place sure go out and get a high dollar OS peice of crap and read more of persons here that do not like GMS motors i wonder how many even own one but has something to say about them your not going to get a good answer here make up your own mind GMS is ok and a lot cheeper.[:@] good luck bro

BigWes

I don't know crap about a GMS engine so I won't say anything about it one way or another. I have known some folks with them and those airplanes were always problematic. Mostly smaller ones if I recall correctly. Anyway, I do like the Supertigers for the price. I am an OS guy myself so I would suggest one of those. You here people bashing an OS because it is actually EASY to get up and running. Some people will say you arent very smart for using an EASY to operate engine cause you should be challenging your skills more. I call bull**** on all of that crap. I love an easy to use easy to tune engine. Maybe it costs a bit more up front but you'll spend more time flying and less time cussing. So, maybe you don't cuss, fine then you'll spend less time repairing damage from an untimely engine failure. I have always really enjoyed it when my old K&B would run great on the ground and for some reason would sputter on takeoff. That always causes constipation if you know what I mean. Anyway I wish you luck on whatever you decide. Do us all a favor and roll some video of the maiden after you get it up and running.

Wes

sdcranford

My Feedback: (4)

Just get a Super Tigre. Great for the money. For a 2 cycle I always go S.T.
The stock muffler is not bad, but can be replaced for a much lighter one if your
plane ends up nose heavy.

Remember that old saying..."you get what you pay for".

flightom

And does someone has/had experience with an ASP engine?

wolfen100

Gms engines seem to be fine...lot of bang for the buck ! Good power...Good idle...Good price... Will pull a tower 40 trainer straight ..."UP".. China has been improving the quality of their product's....Before the tune process, let some heat get into the engine. Don't rush it.. Poor cold weather engine ! Nice warm weather engine.. When the break in process is finished The engine will surprise Your flying buddy's..Make sure the carb is fully seated into the engine. I have Os...Saito..Gms..Tower.. engines....The performance & reliability of the Gms is as good the rest. ( No I do not sell them ).. ( No stock either ) LOL.. Good Luck....

Crash-D

If money's tight and you want a great powerful reliable engine then get the Supertigre engine. They run great with little need for you to ever pull it apart and fix it to run right, they've got a 3 warranty, and come cheap. Personally i'd get a Super tigre over anything but a Jett engineering engine any time!! And those are expensive engines.

My 51 ringed puts out a crap load more power than a buddy of mines O.S. out at the field while I'm swinging a 11x6 hes swing a 10x5 and I'm still kickin his engines a**.

Darion

pauluk2w

My Feedback: (7)

I love ASP/magnum engines. I have found them to be good reliable engines, easy to tune and so far have never had a problem with them. They may have a little less power than some other engines of comparable size but they are IMHO good value for money.

sigrun

Perhaps while you were busy shouting you missed the part where he said, "I need to purchase a .90 size engine and the cash is tight"? Kinda' eliminates O.S. even without consideration of the fact that O.S.' 90FX wasn't exactly free of its own gremlins which came FOC with it in the blue box until quite recently. Just do a search on RCU for the well reported problems with carburation which plagued it for an aeon.

Similarly doing preliminary research for a value engine in that class which runs reliably. Prefer to avoid Super Tigre's G90. Disappointing to hear of the problems with the GMS' quality control.