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HomeRC & PowerAircraftHelicopterEngines Plugs Mufflers Fuel › YS 120 SRX any good ?
09-06-2015 11:04 PM  3 years agoPost 1


Berwick,Victoria, Australia

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Im about to get another nitro and the 120 SRX is the newer version of the older 120sr.
I know there were issues tuning the old version

has anyone got any experience with both who can advise is it worth getting the newer version or just get an OS105 ?

Thanks in advance

ENV - Still laying it down !….Ohhh yeh !!!

09-06-2015 11:18 PM  3 years agoPost 2


The Villages, Florida

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Sorry , I don't have any experience with that particular motor but .....
IMO , you can't go wrong with ANY YS motor !!

Been there, done that and old enough to know better.....

09-07-2015 02:41 AM  3 years agoPost 3


Virginia Beach

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I've been flying the 120SRX for about a year now and have been very pleased with the motor. The larger heat sink head helps with the heat soak on the motor and widens up the tuning window. The biggest help with this motor for me was going to a bladder style fuel tank. It made the fuel delivery incredibly consistent and the tuning has always rock steady with this setup.

I switched over to this motor after having bad luck with the 105 being either inconsistent or the piston ring indexing pin failing.
The YS is not as smooth of a motor as the 105 was but it's an absolute power house even running rich.

If I were buying a brand new motor I would look seriously at the 91 SRX excellent power, Most say better than a 105
I'd go that route Mostly due to the fact Hatori has stopped producing pipes for the 120 and 105. As well as 30 % fuel being easier to source.

09-07-2015 04:19 AM  3 years agoPost 4

rrKey Veteran


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Just an update, Hatori USA is selling pipes for the 120 an 105, they are a little less expensive than the old, I believe they are re-branded Power Boost pipe, you can buy them from Experience and Amain.

Is the YS 120SRX any good?
Well that depends, is it better than the 120SR in tuning? NO!
Does it run smoother than the SR? Yes, big YES!
The carbs are basically the same, so are the sleeves, piston ,ring, and regulator, SO EXPECT TO RUN a bladder tank, the piston and sleeve still get VERY HOT under 3D use, and very easily even with that new head. I have to run a bladder with my 120.
not really relevant, but does it look better than the older YS? In my opinion hells YES!

Does it perform better than the 120SR if you get tuning all right? YES, its waay smoother.

But you also wanted to know if it runs better than the OS 105HZR?
I have two 105 HZR's and never break a sweat tuning any of them, they are awesome. I own all three engines, the SRX since it dropped, till now and the 105's for two years. I have to say I would rather do without the little extra power of the SRX and run my 105HZ-R anyday, the HZR's tuned waay better since day one.
If you must get a YS wait and get the Tareq 96SRX, yes that is right not a typo, the Tareq 96SRX is supposed to drop soon. I heard it has much more torque than the 91srx because it was stroked to 96, and has the tuning and reliability of the 91SRX.

09-08-2015 05:42 AM  3 years agoPost 5


Berwick,Victoria, Australia

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thanks for the heads up guys and especially about the YS 96 !

ENV - Still laying it down !….Ohhh yeh !!!

09-17-2015 11:29 PM  3 years agoPost 6

rrKey Veteran

Morgan Hill, CA. USA

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I stopped using any OS motor after the 91HZ-PSS pump kept failing.
I have run exclusively YS motors for the last 5 or 6 years.

Currently, the 120SR-X is in my Trex 700N and the 60SR is in my 600N.

I've never had any problems tuning any YS motor and I do not run a "bladder" in my fuel tanks. Just run the crankcase pressure.

One guy at our field just finished building a Synergy N7 and used an 91SR (red head) in it.
He got the motor as part of a sponsorship deal about 5 years ago and never used it. The motor was still new in the box.
I watched him fly the 3rd & 4th "maiden" flights yesterday - the 91SR is awesome. With the 695mm blades, he was doing his full routine. Ran 1850 RPM headspeed.
I always dismissed the 91SR and went directly to the 91SR-3DX.

I said he should take a look at the 120SR-X and he said "Why?".
I guess when you fly like him, the extra power of the 120SR-X is not needed.

Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!

10-12-2015 09:16 PM  3 years agoPost 7


Quebec, Canada

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Sorry but what is a bladdr thank???

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10-28-2015 08:43 PM  3 years agoPost 8


Irving, TX

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The bladder tank is basically a latex balloon inside your fuel tank that holds your fuel supply for the heli. Instructions can be found here:

I've had nothing but good luck with my YS 91 SRX Tareq edition motor. I would either use that or wait for the 96 SRX mentioned above (should release next summer). My 120 SRX had trouble and ran super hot in the hot Texas summers when doing hard 3D routines (even running excessively rich).

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10-28-2015 11:19 PM  3 years agoPost 9

rrKey Veteran

Midland, MI USA

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I've been flying the YS91SRX which was built by Murnan Modified Motors in Georgia. Mine was stock, used. Needed a ring. I sent new bearings and ring, and for a few dollars, it came back as an excellent engine. No bladder or header tank in my case. I wouldn't bother. Just Lynx MOAS and Lynx in-tank line. It's been a pleasure to tune and fly all season. I am hoping to see YS successful with the 96 as well. I know there might be more power avialable from the 120, but I sure don't regret sticking to the 91. Mine runs very cool. Barely above ambient backplate, so heat soak simply doesn't come into play. It has more power than I expected and doesn't leave me wishing I had more. Mostly, after a tank, I land and catch my breath!


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