natxo Posted April 21, 2023 Share Posted April 21, 2023 (edited) Hello I have acquired an old FT120 V1 that needs few parts, as is a discontinued unit, i'm posting at some forums to see if i find something. + carburetor + radial mount + propnut As seems very hard to find, if not found i will not be able to use the engine, so i'm also looking to source one FT120 V2. Regards, Jose Edited April 21, 2023 by natxo typo Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 21, 2023 Share Posted April 21, 2023 I assume this is an OS FT120 flat twin? The propnut should be 5/16x24 and i have loads of those available as we used that size on older laser engines and sell them still as spares. I use one of our sleeve nuts on my FF240. The carb is likely to be a problem and you might need to mod it to suit something else. The mount, which was square, should be the same as the ASP FT160 version if you can find one of those (also discontinued). What is wrong with the parts you have? can they be repaired? Photos of the engine and any damaged parts might be handy 1 Quote Link to comment Share on other sites More sharing options...
natxo Posted April 21, 2023 Author Share Posted April 21, 2023 Yes its a flat twin engine, the first version of the Gemini FT120. Its like this one (a reference photo not mine) I only have the piece that makes the base for propeller (don't know name in English). Seems they have: sleeve nut, a washer and another nut. + Radial mount don't exist + Carburetor is broken, internal piece wont turn (don't know name) I will gladly buy one of those prop sleeves, how can i do? Regards Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 21, 2023 Share Posted April 21, 2023 Kinda need photos of the actual engine so the damage to the carb can be evaluated. It might just be stuck. Quote Link to comment Share on other sites More sharing options...
natxo Posted April 21, 2023 Author Share Posted April 21, 2023 Thanks Jon, you are very kind. I leave the engine to a friend that is taking a look to the carb, i will see him at weekend and take some photos so you can see whats the problem. I have found the radial mount in a german shop and ordered it, so only need to solve carb and prop nut. Regards, Jose Quote Link to comment Share on other sites More sharing options...
natxo Posted April 21, 2023 Author Share Posted April 21, 2023 Just to update, also maybe this is useful for someone in a future. Its the same carb as a 25FSR / 25F ABC Maybe now is easier to source one Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted April 22, 2023 Share Posted April 22, 2023 16 hours ago, natxo said: Just to update, also maybe this is useful for someone in a future. Its the same carb as a 25FSR / 25F ABC Maybe now is easier to source one Are you sure that's an awfully small carb for a 20cc engine? Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted April 22, 2023 Share Posted April 22, 2023 (edited) Hi Andythe carb on an OS ft 120was quite small as its supplying two 10cc cylinders one at a time so plenty big enough. Jose . If your 120 has been lying around for a time please strip and clean the big end oil ways. I had one years ago in the "good old castor oil" days . The oil holes were tottally plugged solid with set castor oil. It destroyed the bigends in a couple of minutes even though case was fully flushed with fuel to get everthing moving. Con rods for the mk1 are totally unobtainable now. Fortunately the crank in my engine was usable. I still keep one of the damaged rods on my keyring as a memento . Good luck with it . The mk2 is a far bettr engine. Edited April 22, 2023 by Engine Doctor 2 Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted April 22, 2023 Share Posted April 22, 2023 Good advice ED, please strip and clean the big end oil ways.my Saito 150 second hand and 'only' bench run and with Labema fuel and after run had both of the big end oil ways blocked and no castor in that fuel ! . Quote Link to comment Share on other sites More sharing options...
natxo Posted April 22, 2023 Author Share Posted April 22, 2023 Hello Andy, about the carb i hope to get some photos of mine tomorrow, mine also have 2B stamped on body and i found that info on rcgroups, it looks exactly the same as the one i have, except that mine has a part broken. https://www.rcgroups.com/forums/showthread.php?3982099-Carb-from-OS-25fsr-or-Royal-25 Engine doc, that's a good advice! yes it has been used in a vitrine for loong time, when i received it was "stucked" and need a touch with a hot air gun to be able to turn. Initially it looks like its almost new but sure has been run and have castrol oil residues, so it will need a internal clean. Any concrete point i should pay extra attention? my strong point is not mechanic. Yes i have been trying to find a 120V2 at a non collection price but seems also very hard to find, i want it to put in a plane. Thank you all Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 22, 2023 Share Posted April 22, 2023 If the engine is locked up with castor i would replace all of the bearings as you simply cant get all of the polymerised castor out of them by washing in solvent. Given you cannot get spares for this engine any more you need to make sure you do everything you can to prevent damage and a new set of bearings is not expensive. These engines are quite easy to rebuild. I have done an ASP160, OS FF240 and FT300 in the past. Make sure you use a precision ground hex bit for the conrod big end cap screws to prevent rounding them off. A torque screwdriver at the correct setting would also not be a bad idea when it comes to the rebuild. Quote Link to comment Share on other sites More sharing options...
natxo Posted April 22, 2023 Author Share Posted April 22, 2023 Those are some photos i take from it when i received, my friend removed the "back plate" to take a look... to me it looks pretty good, but as i said i'm not good at mechanics. It wont needed a long time hot air, just a touch to be able to move free, i also didn't want to force it. I will take more photos when come back to me and details about carb broken component. Yes it worth the time to disassemble with care and at any doubt will replace bearings also 1 Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 22, 2023 Share Posted April 22, 2023 In fairness that really isnt bad at all. A decent wash with fuel should, in this case, actually do the job. Be sure to add plenty of oil to the internals before you fire it up Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted April 22, 2023 Share Posted April 22, 2023 If i remember correctly the front crank bearing , a large thin bearing was a special only available from OS so be careful and save it if you can . When i rebuilt mine the bearing was ok but i normally change them anyway but it was unavailable then , 20 years ago. Clean internals and bearings really thoroughly and make sure the balls are free and turn smoothly. If in doubt change them. Quote Link to comment Share on other sites More sharing options...
natxo Posted April 22, 2023 Author Share Posted April 22, 2023 Thanks for all the advises, i will do my best. Its a shame that is not a V2 so i will have no problem getting any spare i will need, i will still buy a v2 if i find one as is a nice size boxer engine that i can put in a plane that fits in my small car. In order to choose a plane... it will have similar power to a 60 2t? Quote Link to comment Share on other sites More sharing options...
David Ovenden Posted April 22, 2023 Share Posted April 22, 2023 I do have an excellent OS Gemini FT120 v2 in its box with instructions. Send me a pm if you are interested Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 23, 2023 Share Posted April 23, 2023 13 hours ago, natxo said: In order to choose a plane... it will have similar power to a 60 2t? They are difficult to compare so i wouldnt bother trying. My ASP 160 twin is more than man enough for an 82 inch seagull spacewalker so the 120 would be a little behind. In this review http://sceptreflight.com/Model Engine Tests/OS Gemini FT-120.html the engine seems to have decent power, although they are using unknown props. i would expect the performance to be somewhere in the range of a 90-120 4 stroke depending on the prop. I would not prop it to run it faster than about 8000 on the ground though as its not really intended to revs itself silly. They dont list a 15x8 in that test, but if you get somewhere around 7500-8500 out of a 15x8 apc then that would be a good choice. I use 17x8 menz wood on my 160, but i cant recall the revs. So 15x6 for lighter load running on the bench after rebuild, 15x8 to fly or maybe 16x6 depending on the model in question. Quote Link to comment Share on other sites More sharing options...
natxo Posted April 23, 2023 Author Share Posted April 23, 2023 Will search then for a easy plane in 90 4t range, to be on safe side. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted April 23, 2023 Share Posted April 23, 2023 Cant comment on power of the V1 FT OS as once I had overhauled it a collector pestered me for it and I let i go . I was told they were................ disappointing ! I did fit a SC 160 FT in the same model that the OS120 came in , a 72 inch a clipped wing cub. It flew like very well and was fast . It could fly slower of course but the SC had a habit of one cylinder going out if run at slower speed . If you are tempted to buy an ASP,SC or Magnum Flat twin (copy of OS) instead of a proper OS V2 make sure both cylinders have good compression as heads have issues with leaks around the valve inserts and replacing head is no guarantee that the new head is not the same due to poor QC Quote Link to comment Share on other sites More sharing options...
natxo Posted April 23, 2023 Author Share Posted April 23, 2023 Well. i don't expect too much. I just get the engine to put in a cub or similar and enjoy the sound doing some low-pass. Thanks for your advice about the OS clones. If i get another one, will be an OS 120V2 or 160, just to be able to source a spare if i need those. Quote Link to comment Share on other sites More sharing options...
Jon H Posted April 23, 2023 Share Posted April 23, 2023 49 minutes ago, natxo said: I just get the engine to put in a cub or similar and enjoy the sound doing some low-pass. The black horse cub will work. A customer flew one with a laser 100 and the performance was excellent. http://www.ripmax.com/Item.aspx?ItemID=A-BH058A However, i cannot believe the price they are now. Quote Link to comment Share on other sites More sharing options...
natxo Posted April 23, 2023 Author Share Posted April 23, 2023 Yes, something like that one, there are also twm and seagull ones. https://www.bigplanes.nl/contents/en-uk/d2045761281_Piper.html Prices really went up lately, 600€ for that bh one... I want to make a bench run first to see how engine works, and i need to find first a solution for carb Quote Link to comment Share on other sites More sharing options...
natxo Posted April 26, 2023 Author Share Posted April 26, 2023 Ok, just to update this, i was able to find a carb and a locknut so engine must be complete. In the search for those components i had the opportunity to get a OS FT160 in nice condition and good price, so i also got it so maybe i will sell the 120 after testing it. Please correct me if i'm wrong, the OS FT160 is much better engine that the 120V1 and i mean not only as is bigger, also the fact that spares can be bought is a big plus. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted April 26, 2023 Share Posted April 26, 2023 According to the OS website the 160 Ge ini is stil available so spares shouldnt be a problem. The 160 is a better more gutsy engine. Quote Link to comment Share on other sites More sharing options...
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