[&:] Hi!

I am writing because i think that we need in the market a new generation of .90 size two strokes engines. Dont you think so??
For example....alot of the pattern kits(including those for 3D) that are available are made for YS.90-1.10 4 strokes, but if you don´t want to use YS(4 stroke) for being so complicated engines, what option does we have?....obviously that there is the .90FX, but i think that O.S. should develop a new engine with pump and with the option of buying it for side or rear exhaust configuration. YS should also made a .90 size for airplanes, there is alot of PATTERN and 3D airplanes in the Market asking for 90 size engines!

Does somebody knows if this companies are having plans of doing such thing??

I agree totally with your situation - I've sold off all my YS's this past year (91 and 63). They just gave me headaches - I'd rather be flying and practicing rather than fiddling with those things all the times.

Unfortuantely, there's not much left to choose from anymore in this size range. I have 2 90 size pattern birds - one a Synergy 90 3D and one a Kyosho G-Trick. I picked up a OS 91 FS-II w/ pump and have flown it on my Synergy which is A LOT lighter than the G-Trick. It could still use more power. Debating on whether to go OS 91 FX w/ pump but hesitate because 2 strokes are messier and noiser and haven't heard the best things about the 91 FX.

The good news is that Webra just introduced (or reintroduced?) their 91 speed which looks great. Still no pump but we'll have to add one ourselves.

What to do? Either optimize kits for the 91 four-strokes (make them lighter or smaller) or explore other engine options.

I'm debating of designing a plane for the everyday engines in this size range, primarily that OS 91 FSII-P that I have. Would be laser cut, of course.

Just my thoughts... sounds like we're thiking along the same lines.

If you fiddle with YS engines as if they are like 2 stroke, you will have a problem. You only need to know a few basic things about YS to derive maximum benefit; yes YS are different; they have to be to produce so much power and torque for minimum weight. I fly YS (most of the time) all sizes without any problem. There is enough information on the YS manufacturers support forum for anyone to tune YS engines. Inspite if someone does not follow, there are several (including myself) who will advise om how to resolve any issues.

i think we need to tell OS to make a OS 100 RX......a smaller version of the 140 RX.

WHy have a pump !! I have a prototype of a ZIMPRO 91 size Viper using a OS 91 fx 2 stroke engine swinging a 15x10 apc prop at 8800 rpm with out of site vertical.. The plane weight is 7# 6 oz and the fuel tank is on the CG and only using pipe pressure !! The plane was designed for the ys 91 and since the engine is hard to come by and the simple 2 stroke set up, thats why this test was done.. Dennis also has carbom fiber option which would also make plane lighter.. We are using a MAC's quiet pipe and a karl M. header.. see photo of the 2 OS 91 vipers... Mine is the red/white/blue.. I dont see the need for the pump with this set up..

Scott

One of the biggest mistakes I reckon people make when tuning a YS is they adjust the idle mixture and don't rev it between adjustments.

If you don't rev up to maximum speed, or near it, for a few seconds between adjustments, you just end up 'chasing' the idle settings and never get it tuned right.

-David C.

When you can buy a OS FX 91 for $199. Adding a pump to it isn't expensive.
A 16x10 or 16X12 on a pumped OS FX91 with wrap-around header & ES pipe is a sweet set up.

I'm impressed with PatternPilot running a NON pumped os with the tank on the CG and apparently no fuel draw problems. I wouldn't try it- a $30 pump is cheap insurance of a good run consistently. JMHO

Now if they build a OS 100 (smaller version of the 140) it'll probably cost 75% of a 140. Also it'd probably be quite a bit heavier than the 91, negating alot of the power increase. If I was gonna spend that kind of money - I think I'd go back to the YS 110 ( replaced the 91) or step up to a 120.

Again -Just My Humble Opinion

ps -I'm putting a YS 91 in my JR Explorer V90

Eddie

We tried the iron bay models fuel regulator for the first 18 test flights and set it just like directions said to and never could get a good engine run, we used both crankcase pressure and pipe pressure and had many problems...The regulator was removed and using the prior set as listed before ... I don't have any fuel draw problems at all in any flight angle.. we picked that regulator from talking with many people about the Cline or Perry set up... The only flame out I have had since going to a pipe pressure set up is when I forgot how long I was up and ran out of fuel... I'm still doing test with different props and will be trying a 4 blade 13.8x10 apc and see how it does... Both airplanes in the prior photo are the same engine set up..

scott

I hope, OS could re-design their 91 four stroke like the new SURPASS 70 ULTIMATE, making it more lite and with more power. Other option could be that also O.S. could develop a new 4 stroke engine 1.00size, like SAITO and YS does.

Webra makes an 80 Race that is a rear exhaust, pumped 2 stroke pattern engine designed for low rpm an high torque. Cost is $350 in the US. I have heard they are very good engines.

saito makes a 100 that is the same physical size as a 90 and it is a good engine.

Bill

where can i buy the WEBRA, Who is the distributor in the USA??

Thanks very much

How does the Webra compare to an YS91 or YS110? Anybody has experience with this engine? I need to buy an engine of this size and was decided to buy an YS but would like an engine of the same performance without the problems of four strokes.

Here is what I think.

Eddie,
91FX + Karl's header + ES carbon? Isn't it higher than YS 110?


For the need of 90 size 2-stroke engine, I went with OS 91SX-H. If I had enough $$, I would have gone with YS 91ST.

Remote needle of OS was one reason that I chose to use 91SX-H. Since I am using 30% nitro for YS engines, I can use the same fuel in the 91SX-H. I bought it slightly used & cheap. Tried it with 91FX muffler, Macs standard header & a tuned pipe. 91SX-H turns 15x8 @10K with 20 something % nitro. I can still get more rpm, but it is still running better than 91AC that I have.

Right now, I have a wrap around-header by Karl Mueller ready to go.
The set up worked fine with a Perry VP-30 last time I tried a few months ago on a stand. (Fuel tank moved up and downabout 12" without any throttle changes).

For a Webra 80 at $350, I would go with a YS 110. It is lighter than YS 91AC/FZ and similar price with the Webra 80. 4-stroke also uses less fuel.

Hi,
I am flying 2x2 pattern plane with OS 160 FX, stock muffler and Perry pump. It turns 16x14 at 7950 RPM noise level is 88 DB. Huge power, no problems at all.
I think that this setup could work with OS 90 FX too and it sounds like very good entry level.
I do not thing that producing a special engine like OS 100 FX with pump is good advise. The idea is getting the chipper entry point to the pattern world. The big advantage of the 90 and 160 size engines is that they are produced in much larger quantities than the 140. That's the main reason why their price is low.

Mike

When I was looking for the Webra, the only US source I found was Pauls Model Supply at www.paulsmodelsupply.com . There are probably some overseas shops that have one as well.

Patternflyer
>Eddie,
91FX + Karl's header + ES carbon? Isn't it higher than YS 110? >

I didn't intend to imply that the complete setup was cheaper than a YS110. I was just bragging about the power( at the wrong time- upon re-reading it I see what you thought ). This thread started out saying there was a need for a new 2-stroke 90 size motor. I was trying to say I don't think you need better power & probably won't get a cheaper price than the existing OS91Fx.

If you stay in the 2-stroke category ( the original topic of this thread) then I think the cost of a header and tuned pipe is automatic and can be assumed irrelevant to the subject of this conversation - as I don't see many 2-strokes running without them.

I should've left my comment about putting the YS91 in my plane out of this thread also. again -the wrong place.

excuse the confusion please.

Eddie

Swlarcham:

Your coments about four stokes are wellcome too!!, the only thing that i start this thread about a 90size engine is that i think is much more simpler the use of a 2 stroke rather than a 4 stroke(and more if is a YS!! je je).
Like i said at the begining........i think that company like OS should develop a good .90size with pump intended for persons like me that we are flying 90 size pattern airplanes or 3D. Besides that, OS should also consider re-designing their four stokes to make them lighter like they made with the .70 size ULTIMATE.
Another option could be that YS could start making the YS91 for Helicopter for airplane too.

I am using a OS91FX powered Swallow 90 with standard muffler. It has power to spare. I will tweak it a little during the offseason. My "el cheapo" plan is to use the Topflite exhaust header (the one used with the in-cowl can muffler in the Topflite scale models - Tower part LXHY77 at about $15) to route the exhaust to the rear. I am thinking of connecting a MACs quite pipe to the engine with some kind of Home Depot flex tubing. I will pump the engine with the Iron Bay fuel regulator using crankcase pressure. I have everything ready except for the pipe and flex tubing. What do you guys think?

does anyone know how i can get ahold of karl? i want to mount my engine inverted on my quest so i will need him to make a header.

Hi folks
Just too throw my two pence worth in.
I have recently bought a webra 80 for an MK skystar 90. It looks a very well made engine but I am a webra fan as I use them in my helis and they have NEVER let me down and proved to be real sweeties to operate.

According to a German gentleman who has extensive experience of the Webra.
It will pull as good as a YS91 but the OS 91 fx has the edge on it but only just.
People seem to be having mixed results with the OS. Some swear by it, some swear at it.

And if you are wondering why I didn't go for a YS
two reasons
1) I live in the UK and high Nitro fuel which is the staple diet of a YS costs the earth over here.
2) 4 strokes and me just dont see eye to eye. and by all accounts anything that needs constant tweaking and a yearly refit is not for me. I like to fly not fiddle.


Mike

TOO bad Irvine doesn't have anything between the .72 and the 1.50 engine... I Guess there is a big hole in their line (

Has anyone looked into the 90 torque from Jett? I think it's a in 60 size case and weighs around 24 oz. It doesn't have a pump, but a Perry or Kline should work if needed. I think the engine would work very well for pattern, and Dub Jett should be able to help recommend a header.

http://www.jettengineering.com

Regards
Glenn