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Old May 31, 2010, 02:15 AM
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Joined Jan 2009
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Os 1.08

Hi All

I thinking about buying a second hand os 1.08 2 stroke, my question is what are peoples opinions on this engine and how does it compare to a new os 1.20AX

I am thinking of putting the engine in a 90 sized pattern style plane such as a fliton inspire 90

Any opinions appreciated


Thank you
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Old May 31, 2010, 11:04 AM
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Everett Wa.
Joined Jun 2001
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The 1.08 is the only OS engine that I measure (on a dyno) that actually produced the rated (advertised) power. From my perspective that is its only outstanding feature.

I haven't run an OS 1.20 AX.

Friends don't let friends fly nickel
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Old May 31, 2010, 12:57 PM
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You will not be disappointed. Great engine.
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Old May 31, 2010, 02:30 PM
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IMHO, the 1.60FX would be much too heavy for the Inspire. My flying buddy has the Inspire90 with a 90-size 4-stroker. It flys like a dream. My 1.60FX is currently mounted in an UltraSport1000. It was also powering a Giant Super Sportster. A good prop for the 1.60FX is a 17x10, which might give you ground clearance problems with the Fliton. Just my .02. Ken
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Old May 31, 2010, 05:06 PM
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Thanks everyone

Ken I am considering the 1.08 or an 1.20Ax not the 1.60FX, however i am interested in your buddy's inspire90 with a 90 sized four stroke, would you mind going into more detail.

Thank you
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Old May 31, 2010, 11:53 PM
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Sorry for the 'senior moment'...I also have an OS1.08FSR which I modified with a Dave Shadel ABC piston/sleeve (no longer being sold.) I was going to use it with a VenusII, but that combo would, imho be too nose heavy as well...The OS120AX is a very versatile and powerful engine. One of my buddies used it in a U-can-do, but now has it in a TF Cessna. My friend's Inspire90 has a YS.91FZ...14" prop...I searched my files, but couldn't find a picture of his Inspire90. Nice plane with plug-in wings. Landing gear a little flimsy. Ken
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Old Jun 01, 2010, 12:37 AM
Airplane Gearhead
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Joined Jan 2005
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They're both great running engines...
The 1.08 is an old school big block...powerful, quality built and excellent carb, but a bit heavy. I put one in a H9 Showtime 90 (side mt. w/ Pitts muffler) and was a nice combination.

The 1.20AX is a nice running engine too...a friend had one in a UCD..no problems with it...pulled it vertical easily. (that one was also side mounted because of tank location issues)

One consideration might be parts availability? You can get bearings and a ring for the 1.08 if you need them...but if you'd need anything else...you're going to have to do some looking around.

I guess I would go with the one I could get the best deal on...either one would probably work well.

I'll have to check...is the 1.20AX lighter than the 1.08?
Edit: The 1.20 is considerably lighter than the 1.08, especially if you add the stock 1.08's HUGE muffler.
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Old Jun 01, 2010, 01:49 AM
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Here's a pic of my OS1.08FSR...you can see the brass cylinder...starts with one backflip...the 120AX would be lighter and more powerful, if you can afford it...Ken
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Old Jun 01, 2010, 01:54 AM
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The weight difference is something i haven't considered, and parts availability could be an issue, but on the other hand the engine shouldn't cost me very much to purchase initially.

Thanks for the Pic Ken, what exactly was the purpose of the Dave Shadel mod.
Also the YS 91 in the inspire 90 sounds very nice. Has your mate had issues with the flimsy landing gear

Thanks
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Old Jun 01, 2010, 12:10 PM
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Quote:
Originally Posted by mricho View Post
The weight difference is something i haven't considered, and parts availability could be an issue, but on the other hand the engine shouldn't cost me very much to purchase initially.

Thanks for the Pic Ken, what exactly was the purpose of the Dave Shadel mod.
Also the YS 91 in the inspire 90 sounds very nice. Has your mate had issues with the flimsy landing gear

Thanks
Shadel (Performance Specialties) piston/sleeve sets were true ABC. The ports were slightly smaller, camfered for better flow, and retimed for better performance across the band. I haven't seen the Inspire lately, but I recall that the method of attaching the wheel pants was not the best, and a cocked pant on landing would tear out the main gear. It was one of the best flyers I've seen. I have an AW Yak54 .90/1.20, but I'm partial to the sleek, precision aerobatic look of the Inspire. I grabbed this pic from the web (not my buddy.)
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Old Jun 02, 2010, 01:19 PM
Pro Bro #1963
Joined Mar 2004
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The OS 1.20AX is an awesome engine!!! Starts very easy and I have been amazed at what little fuel it uses. My vote is for the 1.20 though both engines are very nice!
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