G`Day
Am installing the OS 120 surpass in my 1/7th sizeP-51, just need some feedback on whether I need to install a soft mount for this engine?

My kit comes with the ajustable engine mount, (GP60-120) is this OK to use? I`v been told by the shop I bought the kit from It`s a very good mount !!!

I`m concerned about the vibration this engine might produce !!!!

Also is there on the market a 4 blade prop that can be used with this motor and plane? Like the look, more real to life!!!!!

dutchy50

I dunno....I just put a Saito 1.00 on a Sig 4 Star 60 and even after adjusting it and getting it as smooth as possible on the bench, it vibrates like crazy on the airframe.

So...I would if I were you. I don't know that it can hurt anything, other than your pocketbook. I can't rememeber what they cost last time I saw them...$30 or $40???

The next plane I build with a 4 stroke over a .90 will have soft mounts.

You don't need it

If you must-buy the Dubro Iso Mount. I've used them on several planes, they do work well. Moves the engine a bit forward and some engine movement happens but all in all-good product.
My latest use of one is in a Corsair 60 size with a YS110S (serious shaker) softens it quite a bit.
My 4*60 with a 91 OS has one and it is smooth as can be. 100's of flights on it.

I agree with Ken you really don't need it however, if you do decide to use one from J'tec Isolation mounts.
I have them on two different planes. Nice mounts...

I have the Dubro Isolation mount on a Jerries Big Boy with the OS 1.20 Surpass, the difference is night and day... much less vibration with the mount, period.

I have a number of different makes and models of mounts, anti vibe, they really do work pretty well but I use the GP adjustables just as often without problems so I agree, they aren't something you must have. Out of the mounts I have tried, the best of the bunch was the Jtec anti vibe. It takes a bit more work to mount but it was well worth the trouble. I used it on a CG Extra with a YS 1.40 sport and the air frame didn't even shake. I have an OS 1.20 beam mounted, the old wooden beams that run through the fuse and it isn't bad at all.
4 bladed props?? I haven't seen any but Groupner {spelling} makes a great 3 blade and it can be dyed for color matching, dark colors. I just tested there 14X7 on the plane I'm running a OS 1.20 on, it was OK but not the prop I was looking for, I'm still testing but 3 blades need to be ordered so I'm back to the APC 2 blades. I would like to test the Groupner in a 15X7 or 6 though just to see if one of them would be my magic prop??

Gray Beard
Thanks for all your information, more thinking to be done!!!!!!!!
dutchy50

Just something else to think about. I was mounting another OS 1.20 pumper in an Extra, it was a short term replacement for a YS 1.20. With the GP adjustable mount the engine stuck out too far and the GP mount wouldn't allow the engine to go back any farther, the mount was too thick and the front wheel mount hole was also in the way.I ended up ordering one of the aluminum OS mounts and it made everything fit perfect. The holes were drilled and tapped perfectly too. Take this with a grain of salt. I'm not sure if I was told or read that the four strokes are to at least be mounted in aluminum mounts and not the nylon type because they can torque and flex thus breaking the case of the engine.
Maybe this was just folk lore from the peanut gallery and I over heard it. Just one of those fact or fiction things??
I kit built the Extra I installed the YS 1.40 in and used the Jtec mount. I had the mount in hand and knew what I had to do. I made the fire wall thicker so i could counter sink the mount holes. To get the 2 degrees of right thrust, I have built several of these old CG kits and know what they like, I made a shim that went behind the mount, it too was drilled just for the mount. This way I could dial in any more or less thrust if the plane needed it.
The mount is very impressive but it is more work to mount to the fire wall and lends itself to kit or plans built planes more so then an ARF.
Dang, I'm just full of trivia, or is it just BS??? Perhaps a bit of both???

Gray Beard
I love they wayyou explain things! maybe it is B.S but &gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;I will certainly take all your information on board!!!!!</p>

Great info!
Thanks
dutchy50</p>