RunRyder RC
 5  Topic Subscribe
WATCH
 1 page 1203 views
HelicopterSynergy R/COther › YS and OS SZ91 power/smoothness
01-29-2007 01:57 AM  10 years agoPost 1
MJA

rrKey Veteran

UK

My Posts: All  Forum  Topic

I have just started building an N9 and can't decide wether i should
install an OS SZ or YS91.I already have both engines as well as the older C-spec,so it's not a buying choice as such.The 91SZ i have is the first version with no carb regulator or pump.I know how the C-spec and YS compare as i have run those engines quite a bit but haven't had chance to run the SZ much at all(SZ recently fitted in my Raptor90 instead of the YS91).

I thought the SZ was supposed to be an advancement on the 91 Cspec hyper but have read recently that it is back to being a bit of a vibe monster like the original OS91SXH due to the crank balance.

how much more power does the SZ have over the YS,is it slightly more or lots?
What is the airframe vibration like comparing the YS with the SZ in the same make heli with say both useing Hatori and both useing MPII/5.

Thanks

Martin

PM  EMAIL  GALLERY  Attn:RR  Quote
01-29-2007 08:20 AM  10 years agoPost 2
u.k. sailor

rrVeteran

cambs uk

My Posts: All  Forum  Topic

I don't think the muffler makes a massive difference in this respect but I think the SB18 is probably smoother than the MP2. I haven't got the MP5 yet to know about that.

The YS you already know is a very good fit and forget engine and looking at Nigel Brown it is fair to say has enough power for sure.
I have had the YS, and would buy another but currently run a Cspec big bore and an SZ both fitted with twin plug viper heads, and running 30%.
While I have not done extensive testing my view is that the SZ has the most grunt with the big bore close behind, but definately more than a standard Cspec.
The YS couldn't compete with either at the gearings I was running but when fitted in a raptor 90SE at 8.27 rather than 8.0 etc it came alive and was very good.
I should say I also have the cline system fitted to both my engines so they are similar to the YS in this respect.
The SZ in a Fury Extreme gave a tail kick until I increased the head shims quite a bit, but was then a very smooth running heli with lots of power.
The engines I run have cost a lot of money and I am happy with them BUT if I was going to go and make a straight purchase to fit in my Synergy right now I would be getting a YS.
These are my experiences and oppinions only from my real life observations rather than scientific experiment, but show me what a lot of other people have said about gearing etc seem to be correct in my view, but the fuel used and how the engine is tuned how many shims blah blah blah all makes a significant difference to the end result.

PM  EMAIL  Attn:RR  Quote
01-29-2007 11:42 AM  10 years agoPost 3
Harts

rrApprentice

Victoria, Australia

My Posts: All  Forum  Topic

I have YS in both my N9's at the moment and they run real nice. Its unfair for me to compare to the OS91's I have ran as they were in different helis but nothing I have had pulls as hard as the N9 with the YS.

PM  EMAIL  Attn:RR  Quote
01-29-2007 05:37 PM  10 years agoPost 4
MJA

rrKey Veteran

UK

My Posts: All  Forum  Topic

Thanks for your views.Am i right in thinking the YS won't need any hacking of the cooling shroud?One thing i didn't like about the YS was it tended to snuff out on a low idle during a rolling autorotation,usually when going from inverted to upright.You could make it do it by just holding the heli upright while ticking over,turning it upside down for a few seconds then back upright.It would go noticeably leaner when inverted and then richen up for a few seconds ,richer than normal before settling back again.On a slow tickover it would be enough to put the motor out
Has anyone else had this problem?

Martin

PM  EMAIL  GALLERY  Attn:RR  Quote
01-29-2007 06:00 PM  10 years agoPost 5
Chuckie

rrKey Veteran

Crofton Maryland

My Posts: All  Forum  Topic

Am i right in thinking the YS won't need any hacking of the cooling shroud?
Yes you are correct but note the shroud does need minor trimming when using the SB-16 exhaust header.
Has anyone else had this problem?
Yes I have. No solution found yet but when I do every inverted auto I'm committed to landing just incase the motor cuts off. I did have some luck when running the idle a little extra lean? Or was it rich? I don't remember which but that motor was sold and I haven't been able to get my current one tweaked to keep running. A new one is going in my N9 this spring so I'm hoping this one doesn't cut out when inverted. I think the issue is in the carb and the tank above the carb while inverted would make the motor rich.

All in all I'm still very happy with the YS performance. Pulls +-13 pitch and runs great day to day.

Charles

Please stand by for faster service!

PM  EMAIL  GALLERY  Attn:RR  Quote
01-29-2007 06:12 PM  10 years agoPost 6
ehn

rrApprentice

Fairfax Station, VA

My Posts: All  Forum  Topic

"Yes I have. No solution found yet but when I do every inverted auto I'm committed to landing just incase the motor cuts off."

My Synergy with a YS91 doesn't (and you have flown it and done inverted autos!). Do you think it's my header tank helping, which may be closer to the level of the carb than the main tank?

Long Island Eric

PM  EMAIL  Attn:RR  Quote
01-29-2007 06:21 PM  10 years agoPost 7
MJA

rrKey Veteran

UK

My Posts: All  Forum  Topic

Charles,
So it isn't just a fault with the one i have then or maybe because of the way i had the pressure going to the bottom of the tank in a Raptor.
When i made the idle leaner (than it really should be), it was enough to stop the extra momentary "richness" from stopping the motor when the heli goes from inverted back to upright.There seemed to be about a 2-3 second rich delay before the regulator finally decides what to do with the mixture.The problem with makeing it leaner when i tried it, was to get to the point of idle leaness where it wouldn't do it anymore, it would hang up on a high idle for fun,which was worse than the engine quitting ,as it completely ruined the auto effect :-)
I gave up in the end,settling for a faster idle, which sort of ruins the auto as well

Are you useing a dual plug head on your YS?Just wondering if the extra plug would be enough to stop it choking and quitting.Or maybe an onboard glow would work that comes in with the thr-hold switch:-)

Martin

PM  EMAIL  GALLERY  Attn:RR  Quote
01-29-2007 08:51 PM  10 years agoPost 8
Chuckie

rrKey Veteran

Crofton Maryland

My Posts: All  Forum  Topic

Not sure Eric. I need to look at the heli and tank position again. When inverted the fuel at the top of the tank might be at the right height. It could be the factory adjustment of the regulator as some carbs work and others don't. I have a few old motors and carbs so I might try to find a good one.

Footaba, I don't run the dual plug head on my YS. It would be interesting to hear from someone that elminated this problem by using the dual plug head.

Charles

Please stand by for faster service!

PM  EMAIL  GALLERY  Attn:RR  Quote
01-29-2007 09:11 PM  10 years agoPost 9
RyanW

rrKey Veteran

Edmond, Oklahoma

My Posts: All  Forum  Topic

I have noticed that it usually only happens to me when I am in a sustained forward rolling scenario. It doesn't seem to happen near as often when doing push overs and I don't ever recall it happening on piro-flips (knock on wood)!!! I usually piro on the way down, even if it is a push over, so maybe that disrupts it enough to keep it running? I noticed the other day out of the ten or twelve autos I did, it only died on the one that I tried doing as many rolls as I could on the way down. It didn't help too much that I had a thimble full of fuel on the way up though!

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
01-30-2007 01:32 AM  10 years agoPost 10
MJA

rrKey Veteran

UK

My Posts: All  Forum  Topic

After much pondering,have decided to take the SZ out of my Raptor and use it for the N9.May also get a MP5 for it to try.
I don't believe in buying 30% nitro at UK prices so i think the MP5 will be a better option for power on 15-20 for me,though probably not as smooth as the Hatori SB mufflers.
Also have another Hatori 970 i should try sometime if i can work out a mounting system for it

Martin

PM  EMAIL  GALLERY  Attn:RR  Quote
01-30-2007 09:14 AM  10 years agoPost 11
Stu.

rrVeteran

Abrakebabra Kebab shop

My Posts: All  Forum  Topic

I thought the SZ was supposed to be an advancement on the 91 Cspec hyper but have read recently that it is back to being a bit of a vibe monster like the original OS91SXH due to the crank balance.
Thats a fallousy posted by someone who couldnt tune or shim his engine.

I am an OS hater, I loved YS's.

However OS nailed it on this one, it is smooth, reliable andf if properly shimmed tuned, INCREDIBLY powerful.

It is really not worht reading some posts on RR sometimes. Full of supposition, symptom curing rather than the cause etc etc.

Stu

www.waterfoothelis.com

PM  EMAIL  GALLERY  Attn:RR  Quote
01-30-2007 10:21 AM  10 years agoPost 12
DS 8717

rrProfessor

Here wishing i was somewhere else

My Posts: All  Forum  Topic

Yes the new OS is a vibe monster. People that are using it in the Stratus are having problems because it's bolted directly to the bottom plate. Mabey #5 will get it right.

YOU ONLY LIVE ONCE..IF YOU LIVE IT RIGHT THATS ALL YOU NEED

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 1 page 1203 views
HelicopterSynergy R/COther › YS and OS SZ91 power/smoothness
 Print TOPIC  Make Suggestion 

 5  Topic Subscribe

Tuesday, December 12 - 2:55 am - Copyright © 2000-2017 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online