1.05hz vs 91srx vs 120sr

[heraldo]

Hey guys
Got a G4 here with a 91 speed. Looking for more power and have the above motors to choose from. Have some tuning experience but not a lot. Tunability is pretty important.

Appreciate anyone's input.

[Glenn Goodlett]

I like the 105 over the 120. I have never owned the 91 but have only heard good things about it and some swear by it.

I don't think you are going to make a lot more power with any of the above. Noticeable, yes but not a great jump in HP.

Also the 105 is a short stroke and would benefit from running the 115 tooth main gear. Again, it's not a drastic change but noticeable and it will certainly fly at either ratio.

As far a tuneability, I think the 105 wins with the 91 a close second and the 120 a distant third.

As far as raw power, the 120 wins with the 105 and 91 in a battle for second place. Again, I never owned the 91.

The more I think about it, I would not recommend the 120SR to anyone due to tuneability.

[LoveToFly1]

the 105 is a drastic increase over the .91. extremely noticeable. the os will be easier to tune, but the 120 will blow the 105 away also. all in what your looking for. tunablity or power.

[jwatts007]

.....

[Paul Johnson]

I run the YS 91srx it runs very strong easy to tune makes lots of power can't go wrong with that motor.

[MikeG4936]

Originally Posted by jwatts007

Anyone who cannot tune a YS 120 cannot tune an engine full stop...whether the SR or SRX both are bullet proof and perfect for the G4....flown mine for over 3yrs and still going strong...very reliable and user friendly...

Sorry, this is just not true - at ALL. Ask Tim Jones the nitro man himself. The 120 works really well in cooler ambient temperatures. Unfortunately, in places like Texas where we regularly see temperatures of over 100 degrees F, the motor would inevitably heat soak and lean out after about 3 minutes of hard 3D. In these extreme temperatures, you cannot richen it enough to avoid this behavior.

OP - get the 91SRX - especially if you live in a warmer climate. Easy to tune, probably make as much (if not more) power than the OS.

[jwatts007]

....

[bobc2]

Wow! Thanks for the great info JWatts. I was wondering why so many YS120's were selling so cheaply. No problem with the engines, just bad pilots/tuners.

I am going to start buying them up.

[Guiwee]

I have all three. the 91srx is probably my most powerful motor.The 120 I could never get right.The 105 I put in my tsa and haven't looked back yet!!
P.s. If anyones interested I have a 120srx and pipe for sale for 350$

[Matt Nasca]

This is Tim flying "I think" the 91 SRX... could be the 120 but I think he's already changed to the 91 by this video... WOW

Tim Jones Flying RCHO First Fun Fly! (6 min 30 sec)

[jwatts007]

....

[matt blaisdell]

The 91 srx is a killer motor, I have seen a few 105 os , Just opinion . not impressed with the 105.

the ys 97 will be out soon. i have seen that motor in person

Hold on to your shorts with that one

[Guiwee]

Why the need for a 97 if you already have a 120??? Says a lot to me!

[Rodney Kirstine]

I own a 105 and a 91SRX. The 105 is in my N7 and the 91SRX is sitting in a drawer. Just my opinion.

Actually, I may give the 91SRX a try again, sometime. Once I got the updated high speed needle valve seat for my 105 it has run great. It makes great power and has been easy to tune.

[Rob43]

---

[joecass2]

The YS 120 was made to run on 15% I'm pretty sure

Would the OS 105 do just as good on 15% or would the power be gratly decree.

If I were to get the OS 105 I would have to run it on 30% most likely?

[Rodney Kirstine]

In my experience, the 105 runs better on 15%.

[joecass2]

Originally Posted by RodneyK

In my experience, the 105 runs better on 15%.

Nice

[ticedoff8]

If the OP is still looking for a motor:

The YS 120SR-X and the matching Hatori are hard to beat.

I have flown my Trex 700 on the YS 91SR-3DS and the difference is very noticeable.

I fly in Northern Calif and we don't get too many extremes in temperature.
But the YS 120SR-X did fine for me when I was flying it on 98 - 100 degree days

I fly with a 50/50 mix of Byron's Rotor Rage 30% and 15% nitro. That give me around 22% and it works in my Trex 600N with the YS 60SR.
I would not fly the 120SR-X on straight 30% nitro.