OS .91 FS Parts
11-22-2009, 11:46 PM
#5
RE: OS .91 FS Parts
I figured most of the parts would fit. I may need a piston, sleave and cam in few years. I have a couple of .91 FS's that have been real gems for a long time. One is getting up to around 100 hours run time. The other is probably still around 40 hours or so. I'm putting that one in the plane and giving the broke one a good going over and thorough cleaning.
Edwin
Edwin
11-22-2009, 11:56 PM
#7
RE: OS .91 FS Parts
The piston ring and sleeve are identical on the two engines
The II cam differs by being cad plated which often peels off the lobes but is otherwise the same
The II crankshaft is cross drilled in front of the rear bearing to get oil past the shields of the rear bearing but interchanges perfectly
The area that doesn't fit without replacing as a unit is the Head - intake manifold - Carb - Back plate because the II carb sets in the middle. Also the glow plug on the II is recessed 2 mm farther into the head.
The II muffler has a baffle in the center with a hole through its center. The original muffler was hollow.
The II cam differs by being cad plated which often peels off the lobes but is otherwise the same
The II crankshaft is cross drilled in front of the rear bearing to get oil past the shields of the rear bearing but interchanges perfectly
The area that doesn't fit without replacing as a unit is the Head - intake manifold - Carb - Back plate because the II carb sets in the middle. Also the glow plug on the II is recessed 2 mm farther into the head.
The II muffler has a baffle in the center with a hole through its center. The original muffler was hollow.
11-23-2009, 12:03 AM
#8
RE: OS .91 FS Parts
Good info, thanks a bunch. Looks like I need to take good care of the valve train. That may be hard to do. Either way, I'm just trying to squeeze a little more life out of these two engines since they've been so good over the long haul.
Edwin
Edwin
11-23-2009, 03:30 PM
#11
RE: OS .91 FS Parts
FSa-81 and 81P are available. Many parts carry over from the 91.
http://www3.towerhobbies.com/cgi-bin...I=OSMG0981&P=Z
http://www3.towerhobbies.com/cgi-bin...I=OSMG0981&P=Z
11-23-2009, 05:05 PM
#12
RE: OS .91 FS Parts
Yeah, I know there are newer engines. I'm just partial to this engine since its been so damn reliable. The only times it gave me trouble was at the high hours mark when it needed maintenance. Oh well. I've labled a drawer in my engine parts bin for this engine only and will start stocking up on parts.
Edwin
Edwin
07-31-2010, 09:04 PM
#13
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RE: OS .91 FS Parts
does anyone know where i can get a crankshaft for this engine, WITHOUT the pump, i cant find it on the web, also, does anyone know if the crankshaft with the pump is the same???
http://www3.towerhobbies.com/cgi-bin...?&I=LXCH87&P=7
i can only find this crankshaft, not the one with out the pump.
http://www3.towerhobbies.com/cgi-bin...?&I=LXCH87&P=7
i can only find this crankshaft, not the one with out the pump.
07-31-2010, 09:41 PM
#16
RE: OS .91 FS Parts
I have two OS 91 Surpass II engines non pumped
I bent the crankshaft of one in a crash when the sun got in my eyes.
I installed a new pumped style crank in the bent engine and it runs perfect
The pumped crankshaft will also fit in the older OS 91 Surpass I engine.
I compared the old and new crankshafts and they were identical
I bent the crankshaft of one in a crash when the sun got in my eyes.
I installed a new pumped style crank in the bent engine and it runs perfect
The pumped crankshaft will also fit in the older OS 91 Surpass I engine.
I compared the old and new crankshafts and they were identical
08-01-2010, 08:29 PM
#20
RE: OS .91 FS Parts
ORIGINAL: Kimhoff
If money is an issue you can go with the Mag Crank. I belive W8ye confirmed it works up in post #7
If money is an issue you can go with the Mag Crank. I belive W8ye confirmed it works up in post #7
12-03-2010, 08:36 PM
#21
RE: OS .91 FS Parts
w8ye,
I have a question with regards to the bearings of the OS 91 FSII and magnum 91rfs. I'm about to order the rear bearing for the magnum (I could hear it already) and I noticed that it's the open type compared to the shielded type with the OS. Can I put the rear OS bearing to the Magnum? You mentioned earlier that the OS crank has a cross drilled hole in front of the rear bearing for lube. One more thing, the rear bearing for the magnum measures 15x32x8 (boca bearing #mr16002) whereas the OS rear bearing is 15x32x9 (boca part # mr6002zz). Will the extra 1mm thickness be a problem? Thanks for the help.
ton2di
I have a question with regards to the bearings of the OS 91 FSII and magnum 91rfs. I'm about to order the rear bearing for the magnum (I could hear it already) and I noticed that it's the open type compared to the shielded type with the OS. Can I put the rear OS bearing to the Magnum? You mentioned earlier that the OS crank has a cross drilled hole in front of the rear bearing for lube. One more thing, the rear bearing for the magnum measures 15x32x8 (boca bearing #mr16002) whereas the OS rear bearing is 15x32x9 (boca part # mr6002zz). Will the extra 1mm thickness be a problem? Thanks for the help.
ton2di
12-03-2010, 08:44 PM
#22
RE: OS .91 FS Parts
The bearings are different in these two engines. You must use the correct size for the engine you have. You would think they would be the same but such is not the case. If you mix the bearings up, you get into trouble with the spacing and the crank will not maintain position.
It doesn't make much difference on the rear bearing but most people remove both shields on the rear bearing on either engine.
It doesn't make much difference on the rear bearing but most people remove both shields on the rear bearing on either engine.
