tonywayne

I have a gms 120 with only about 4 tanks ran threw it. My gms seems to have less max rpm compared to other gms 120 vids iv seen. Is it becaus its not fully broke in or do i need to use a smaller prop? it has a 16 * 10 on it now. Here is my video http://www.youtube.com/watch?v=kxAZfS4BeFw Thanks

bobrev06x

have you had a tach on the engine? sounds like it's running pretty nicely on the video. that 10 pitch prop might be a bit much for it if you're looking for more r.p.m.s might want to get the thing mounted in your plane a flying for some more prop testing. i've got tons of props that i use for testing and finally, you'll find a combination that suits you. best of luck. thats a strong engine. i have GMS smaller sizes....61...47...40 they run good

alan0899

G'day Tony,
Try a 16x8, a 16x10 may be a bit much for the 120, I use 16x10's on my 160FX.

Gregor32

My Feedback: (1)

Brian Winch has just done a review in an australian mag on this motor his results are with 20% coolpower 10%nitro all apc, 15x8 9600, 15x10 8900, 15.5x13n 7100, 16x6 9300, 16x7 8700, 16x8 8200, 16x10 7800, 17x6 8900
Greg.

Harry Lagman

Tony, I get about 7900 rpm on your video. What sort of prop is that? Even though it's nominally a 16x10, loads can vary greatly between prop brands/models.

I ran in a new GMS 1.20 for a guy with an MA classic 16 x 10. Once it had run a couple of tanks though, it could reliably peak at about 8300 rpm.

Flyboy Dave

My Feedback: (21)

....7,900 RPM isn't even close. This is a revving engine:

Displacement: 19.9cc (1.20 cid)
RPM range: 1800-14,000 RPM
Bore: 30mm (1.18")
Stroke: 28.2mm (1.11")
Weight:w/o muffler, carb, drive washer, prop washer glow plug or nut
750g 26.5oz
w/muffler 879g 31oz
Horsepower: 3.3 BHP @ 13,000 RPM


....put a much smaller prop on it, and get it running between 11 and 12 thousand RPM.

FBD.

longdan

I have several GMS engines, both ringed and ABC - albeit smaller than yours, and my experience with them is that they need a lot of breakin. I would fly them after about 20 minutes of bench running, but I noticed they all got gradually better and reached their best with about 1 - 1.5 hours on them.

WALKERS210-RCU

My Feedback: (36)

I about to post questions about the GMS 120 and ran across this one. From what I can tell from most users the GMS 120 seems to be quite a good engine. I have only had experience with one GMS back a couple of yrs ago, it was a 36 size (I think) and it performed very good. So how many Thumbs Up on this engine

tonywayne

Hi thanks. The prop is a 16*10 master airscrew scimitar profile.

tonywayne

I give this engine 3 thumbs. As you can see from the video link in my origonial post it runs like a charm for only having a couple tanks ran through it and i had it running pretty rich, hent the splutering and smoke. Im just a little concerned about the rpm's. Dont get me wrong it has a good top end and believe me it pulls hard. " i had a big stone in the back of that stand to keep it from toppeling over in the video''. I gues ill have to break it in more and experiment with different props. Thanks alot for the replies guys..