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HelicopterThunder TigerOther › WHICH 91 for my Raptor SE
11-26-2006 07:08 AM  11 years agoPost 1
h2jringo

rrVeteran

Redmond Oregon

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Alright I know this is going to stir up a debate.
I heard YS 91 is easier to tune and more reliable than the OS 91. I got a SE 90 coming and no engine yet. I know OS is more power but Ill take reliablity and non tinkering anyday than a little more power. I just like to know your experience and also does either one make a difference in fuel consumption or are they both just heavy drinkers.

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11-26-2006 07:21 AM  11 years agoPost 2
DOKEY

rrProfessor

Northamptonshire UK

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I know OS is more power but Ill take reliability and non tinkering any day than a little more power
I think you have just answered your own question. . . .YS

Still give exceptional power, other option could be the )S91sz with cline carb, which gives you the reliability as well as the power but at a cost !

I am very happy with both of the above power options, if I ha to pick one then it would be the YS91 due to cost, and a good solid reliable engine out of the box (also it runs a little smoother than the OS)
Forget the fuel drinking syndrome, you are entering the 91 engine zone, they drink fuel full stop, you dont get power without a down side.

Ryan.

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11-26-2006 07:28 AM  11 years agoPost 3
AGRAV8

rrProfessor

Mosquito Coast......Houston Texas

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I agree
YS for the long haul.

GOOD guy list-39, BAD guy list-0

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11-26-2006 10:18 AM  11 years agoPost 4
S Bell

rrApprentice

Nova Scotia Canada

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I think while the YS is very easy to tune the OS will last longer, plus the OS tunes fine. I don't like the way the muffler threads into the YS crankcase material. These tend to back off if not secured in the best manner. You don't want to strain the base metal causing cracks but you want it to stay put. This can limit exhaust applications for wise modelers flying heavily,

YS is a good engine but the casting has been punched out to the limits. OS have a specific 90 casting and use through bolts for the exhaust mounting. YS parts can be hard to get and it uses a metal rear bearing cage.

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11-26-2006 11:01 AM  11 years agoPost 5
Andreas

rrVeteran

Sweden

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Hi.

My OS91 SZH PS is just as easy to tune as my YS91 was. Also the OS has a little more power.

Andreas

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11-26-2006 02:10 PM  11 years agoPost 6
BlakeMcBrayer

rrElite Veteran

Georgetown, Ky

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YS, NO LESS!!

It comes out of the box ready to fly, no mods required. Plug & Play.

As for the muffler threading into the case on the YS, I'm not crazy about that either. I have never had any problems with it though. One of my YS's is 3 1/2 years old with around 100 gallons through it and I have never had any muffler thread issues with it, nor the other two newer ones.

Our club is mostly all YS for this reason, except for our resident 3D guy. This summer he had a unpumped version of the OS91 SZH and had troubles with it going lean some times. Then he switched to a pumped version and went through three pumps. Now he is back on an unpumped version with a few hundred dollars of regulator and head upgrades and it is doing well.

Mean while, I have been flying my YS 91's all summer long while he has been mostly flying his 50's while trying to line his 90 out.

.

Don't come off the throttle untill you see your GOD!

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11-26-2006 04:11 PM  11 years agoPost 7
h2jringo

rrVeteran

Redmond Oregon

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Wow thanks for the replies guys. Not much from OS guys so I guess YS is it.. I know OS hyper 50s have problems with bearings going out some just after 3 gallons that kind of scares me if 91 might have simular issues..
One of my YS's is 3 1/2 years old with around 100 gallons through it
Very impressive to say the least 100 gallons never heard of OS going that long without overhauls.

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11-26-2006 04:20 PM  11 years agoPost 8
SPB

rrElite Veteran

Athens - Greece

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I think you made the right choise. Since I set upmine I never touched those needles again. Plenty of power and very reliable.


Sotiris
myhelis.com Flying Team

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11-26-2006 07:42 PM  11 years agoPost 9
montarok

rrKey Veteran

Brooklyn, NY

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My OS 91SZ pumped was ready to go out of the box no mods, and its been as sweet as any engine can be. I was going to put YS in my 90SE but was advised to get the SZ, guess what, I sold both YS a couple of days ago.

------------------------------------
www.carifuna.com

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11-26-2006 08:57 PM  11 years agoPost 10
AlanR8

rrKey Veteran

Saddleworth near Manchester (UK)

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Can't remember the last time I had to tweak the needles on my YS.

Fit...fly....forget!

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11-26-2006 10:45 PM  11 years agoPost 11
FireStarter

rrApprentice

England

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Get a OS 91 C-Spec with a cline big bore carb on it, Even more power than the standard OS and REALLY reliable too

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11-27-2006 12:14 AM  11 years agoPost 12
BlakeMcBrayer

rrElite Veteran

Georgetown, Ky

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One of my YS's is 3 1/2 years old with around 100 gallons through it
BUT, upon reaching the 100 flight mark on any new YS, I automatically replace the bearings with these:

http://www.mcintoshcentral.com/rc-b...f4cd99e814b09cb

After replacing them at the first 100 flight mark with the above bearings, I have NEVER had to touch the bearings again. My 100 gallon motor has around 500 flights on it since I replaced the bearings with those.

.

Don't come off the throttle untill you see your GOD!

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11-27-2006 12:15 AM  11 years agoPost 13
BlakeMcBrayer

rrElite Veteran

Georgetown, Ky

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h2jringo

BTW, what brand and nitro % are you planning on flying?

.

Don't come off the throttle untill you see your GOD!

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11-27-2006 02:01 AM  11 years agoPost 14
ThunderRobo

rrKey Veteran

Toronto, Canada

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YS = the way to go!

Derek
Da' kid with the toyz!
"Time for some Muzak!"

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11-27-2006 05:50 AM  11 years agoPost 15
Costas

rrApprentice

Adelaide - AUSTRALIA

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The current SZH series of OS heli motors are excellent. More power than the YS and definitely set and forget as far as tuning/fiddling goes.

A lot of ill/miss informed people blame the current OS91 SZH series when in fact it was their earlier series (SXH C-specs etc) that they had issues with. Basically the carby for the earlier series required some modifications for the motors to run well in some instances.

The latest SZH series (pump or non-pumped) which have new carbies on them produce more power than the C-spec engines and a reasonable amount more than the YS.

I have had a couple of the SZH-PS motors and basically you run them out of the box, tune as normal and then thats it - No fumbling around is required.

Just ensure that people do not confuse the OS SX series with the current/latest OS SZ series of heli motors - They are totally different animals...!

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12-01-2006 01:17 AM  11 years agoPost 16
carlyle

rrApprentice

Stratford, Ontario, Canada

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I ran a YS for a year or so... Blew it up 3 times.

The YS is a great engine if your not pushing your helicopter, and just need a smooth running engine. You don't have to tinker with it at all.

But, like I said, run it over 15,000 RPM,and your asking for it. Again, I blew mine up 3 times.

I've since switched to the OS 91 SZ PS, and I love the new engine. It really is great.

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HelicopterThunder TigerOther › WHICH 91 for my Raptor SE
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