Im New to YS engines.

[R-4-L]

I had a stratus here that showed age. started cleaning and rebuilding it, it had a YS engine so I bought my first YS engine yesterday , it has an MPII pipe too.

I have no experience with YS engines so are there any tips y'all could share with me? break-in? needle settings?

Thanks,
Ali

[DavidH]

Use the settings in the instructions. From my experience the YS will like a Hatori muffler better than the MPII.

David

[Gary O]

R-4-L,

I run YS engines quite a bit. First, one thing some people get confused about is the needles. The high speed needle is the short one on a YS, and the longer one is the mid range. The one thing on a YS that is very sensitive is the low end setting. If it's a little on the lean side it really affects the over all running of the engine. I can check one of my engines a little late this afternoon and see what my settings are but it may vary depending on climate. With the heat and humidity here I'm a little richer on all my settings than the instructions say. If I set one per the instructions it's lean and cackly. The best pipe I found for YS is the SB-16 Hatori. Also, they like the gear ratio of 8.45 to 1. It's okay at 8.18 but 8.45 is where they seem the happiest. If you're coming from OS just watch your collective management since you can bog even a fine tuned YS. They are great engines and once set you rarely have to change anything, they just don't have that brute punch like an OMI set up OS.

[R-4-L]

Thanks alot david and gary,

the stratus I have is geared 8.45 for YS so hopefully that should be fine. my settings are probably going to be very close to yours gary, hot climate here. the stratus came with an MPII and i don't wana spend more as I am not yet very sure whats the condition of the heli until I fly it abit. if OS and gear ratio conversions were available here in kuwait i would've gone with OS.

price was reasonable here, YS 91ST 80KD ($1 = 0.29KD), so fingers crossed, if things go well, i'll upgrade the pipe and actually fly this heli all season.

didn't have a close look at the stratus before, man the design is amazing, I specially liked the modular upper and lower frames.

Thanks again all

[Gary O]

Just remember that with the MPII it's going to be quite a bit different than with the Hatori. The MPII was actually designed around the OS which has substantially more bottom end than the YS.

[R-4-L]

i always thought that both MPII and Hatori will produce similar results! as in both are quality exhaust systems. seems im wrong. I mean how much difference are we talking here?

[DavidH]

Curtis designed the MP II around an OS 91 engine. It will bolt onto the YS. But the YS seems a lot happier with a Hatori SB 16 on it. That is my opinion. Plus the MP II is approximate 3 ounces heavier than the Hatori.

David

[Gary O]

The Hatori seems to aid in giving the YS a little more back pressure to work with which helps with the low end response, and overall power band. With the MPII the power curve is a lot more sharp whereas with the Hatori it's more broad.

[DanW]

I tried a MP II on one of my YSs and it did not like it at all! :arggg:

Put the Hatori back on and smooth and happy again!



Dan

[R-4-L]

I see now, never knew that info.. thanks bros.

[Wa11banger]

I run all YS's and all MPII's, they are just a touch heavier but not ounces, mere grams, or maybe an ounce I can tell you when I get home as I have both available. The YS will run sweet on a Hatori muffler or a MPII, I feel from my experience with both that the MPII gives more power but is a bit more finicky to tune.

Power: MPII more power, Hatori not far behind but behind

Noise: Hatory quieter, MPII is very loud in comparison

Tunability: Hatory easier to tune, MPII not hard to tune per say but harder to achieve peak performance.

Price: No comparison the MPII is 33% less than the Hatori.

The hatori is definitely softer on the needles than the MPII but I like the MPII for raw power output. Once I get on top of the pipe I stay there really a treat even though a bit noise.. I should say I break the rules and run an 8:27 gear ratio with my YS's and they couldn't be happier. Which ever you choose either will be a great pipe. You will develop gobs of power on a YS with 8:45 but it might be missing a little pop.

Just my .02
Rick

[Alfred]

The Hatory 937 is the other alternative to the SB16.
It does well on 20% Nitro.

[DavidH]

The problem with the 937 is that the header is shorter than the SB16. So the muffler will be right up against the mechanics of the heli. Even the new style Stratus would have to be offset more towards the right side to clear the muffler.

David

[Alfred]

David
I am using the 937/YS91 in my Stratus.
I will chase down some pictures.

Even the new style Stratus would have to be offset more towards the right side to clear the muffler.

I am assuming that you are talking about the new tank?

[Alfred]

This is the 937 mounted on a new full kit Stratus.

[Blair]

ys91 with MPII @8-1..nice quiet smooth power.

Blair

[DavidH]

Alfred,
I was just saying the 937 has a shorter header. The SB 16 will be away from the mechanics more. I have seen a 937 on a Stratus. Once the owner saw an SB Hatori from Hatori USA he wished he had gotten the SB muffler. Rich has the headers made a few millimeters longer. Both of them will probably run close to the same.

David

[Alfred]

Yes the 937 is close to the frame meaning your tank sticks out even further to the other side to get the minimum of 5mm clearance.
The reason I suggested it is because I don't know what he can get his hands on.
This just gives him another choice depending of what is easier to get his hands on.