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Old Dec 21, 2011, 02:13 PM
A HOARDER ONCE MORE....GEEZ!!!
Plasmajoe's Avatar
United States, NC, Lexington
Joined Mar 2011
100 Posts
Help!
OS GEMINI I vs. II

Can someone explain to me the difference between the two series. I have tried to figure it out, but have struck out!

Thanks, Gordon
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Old Dec 21, 2011, 03:03 PM
UAS Pilot/Tech Instructor
CryHavoc's Avatar
United States, CA, San Diego
Joined Apr 2000
1,441 Posts
Gordon, I think the pushrods were redesigned/strengthened and the crankshaft is different somehow, i.e. bigger journals, harder material or something like that.

If you haven't already seen this thread it has more info - http://www.rcgroups.com/forums/showthread.php?t=1360292

Mike
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Old Dec 21, 2011, 03:44 PM
What - Me Hurry?
redball8's Avatar
United States, IL, Naperville
Joined Jul 2004
43 Posts
The FT-120 Gemini was the first four-stroke twin OS produced. The FT-120 II (Gemini II) was a redesign based upon their experience with the FT-120 and FT-240 Super Gemini. That redesign brought us the FT-160 and FT-300. The FT-120 II thus shares many parts with the FT-160, whereas the FT-120 is a bit of an orphan like the FT-240.

Rap on the FT-120 was that the crank would snap in a crash or prop strike, but I have no first-hand experience of such. One certainly sees more Geminis than Gemini II's NIB.

I'll look for the MAN article and post it if I find it.
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Old Dec 21, 2011, 03:44 PM
A HOARDER ONCE MORE....GEEZ!!!
Plasmajoe's Avatar
United States, NC, Lexington
Joined Mar 2011
100 Posts
Thanks!
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Old Dec 21, 2011, 04:33 PM
What - Me Hurry?
redball8's Avatar
United States, IL, Naperville
Joined Jul 2004
43 Posts
Couple of articles from 1985 shed some light. The engine review points out differences between the original FT-120 and FT-160. Note that the cylinders/heads from the FS61 and FS90 are the same as the FT-120II and FT-160, for example. The "Foreign News" comments about Japan are also a bit helpful ...
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Old Dec 21, 2011, 06:30 PM
Registered User
Joined Jun 2011
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One big difference is the carb. The II has a better carb. I own both engines and they perform about the same. Never had any problems with the original at all.. Bought it in 1981.
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Old Dec 28, 2011, 06:06 PM
Registered User
USA, IN, Seymour
Joined Oct 2009
235 Posts
Gemini Engine

I too have an OS 4 stroke book with all part numbers and pictorial descriptions. PM me if you choose or need too. Larry
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