GMS engines

They are great engines! There are very few that offer the performance for the money. The TT is a good second choice.

In brute strength, there is no other engine under $100 that can beat it.

One of the problems with the GMS engines is the darn thing won't shut off. Some have had sucess with smearing red rtv around the carb. GMS engines are not for a newbie with little to no experience. The Thunder Tiger or Magnum engines would be a better purchase. Evolution has a 40 something sized engine that is guarranteed to work without problems right out of the box. All these engines are under $100 USD. If you insist on GMS, then seek out

Ed

Oh btw: stay away from MDS engines. Nothing but trouble and you'll just go nuts with fustration.

Ed

Won't shut off? Even if you pinch the fuel line?

Here's a repost of my "GMS .47 Mini-Report":

Got my GMS .47 on monday may 20. All the way from merry England.

Wednesday evening i ran three tanks through it without making much of an attempt to tune the high and low speed needles other than to set the top end a little rich, because i found out early on that each adjustment affects the other.

Prop was a 10x5 zinger, fuel was my infamous "platinum break-in formula," the result of many bottom o' the can pourings and with enough additional sig castor added to bring the oil content to around

Never at any time during the short break-in, which was done on a test stand, did the engine sag from a peak setting, but i kept peak runs short and to a minimum until the third tank.

Sunday and monday i had the chance to fly this engine in a Modeltech Magic. 2.5 oz. total or one additional oz. of lead were required in the tail to balance the airplane with the GMS in place of the Fox .46; about 1/4" behind recommended. I adjusted it to idle reliably (but it wouldn't shut down with the carb fully closed), and adjusted the high speed a few hundred rmps rich. Prop was APC 12.25x 3.75, fuel Powermaster 15% synth/castor blend.

After nine flights of about eight minutes or so each i'm very pleased with this engine. It no longer seems as though the high and low speed adjustments interact. By setting the idle at what to me is a wee bit lean, the engine will now shut off at no throttle. High speed was set just a tad rich from peak. Accelleration was quick and firm, no deadsticks were encountered. Plug was the same tower power plug i used for break-in.

Despite my suspicions that an 11x4 APC might be the best performing prop for this airplane/engine combo, the APC 12.25x3.75 roolz, and i think it's because this engine has more than enough moxie to handle it. The large diameter and heavy-ish weight may help the prop to act as a gyroscope, possibly, who knows? All's i know is that it was easier for me to hover and i hovered better and longer than i ever could before (which is to say, "not very well, but best yet"). The airplane would easily and instantly accellerate vertically from a nose-up hover, or any other position for that matter. Yee hah.

Apololgies to the technically-oriented. I haven't tached this engine yet so no numbers, mainly because i already know that the Magic and the GMS .47 makes for a good combination and that's all that really counts.

Texas Pete AMA 59376

ps - The engine shutdown/"lean" idle situation was corrected forever by tightening the needle valve assembly to the carburetor body. I've got many happy hours on this engine now and it's still clean as a whistle. If there's a better value in the .46 size I don't know about it.

TP

Thanks Guys... this newgroup is great... lots a good info for the uninitiated... I'll be posting my next again soon.. Certainly appreciate all the help.

Thanks, Pete. That pretty much echoes my experiences with them. I replaced one of the famous Raptors with one on my trusty Ballistick and I think I get better performance. This is due to the fact that the GMS turns an 11X6 a little better than the Raptor.

opps. thanks damien

Ed

| not even if you cut the line in two and throw a shop rag in the prop!

Now THAT would be damn cool!

Seriously, pinching the fuel line kills it, as will pinching off the exhaust, holding the spinner, making it into a lawn dart or putting your hand/face/leg/etc. into the prop. (I don't suggest the latter three methods of stopping it, however.)

The complaint is that you cannot kill it by putting the throttle all the way down. I don't have any GMS engines, but I have a Tower Hobbies engine (which I hear is just a rebadged GMS engine) and it suffers from this problem. It's really not a big deal, at least not to me. But some people feel it's unsafe if you can't kill your engine at will from your transmitter.