RE: Old O.S. .61 SF
 

Jaka....

....have you ever flown a float plane ? The drag is about twice the normal, in
flight. Getting airborne is even worse. :eek:

Putting a .61 engine on a .46 plane....the plane having been converted
to floats would be quite normal. Putting an APC prop will not help a darned
thing.....contrary to your mind-set....that no plane will fly....unless it is
equipped with an APC propeller. :eek:

Are you on planet Earth ?:D

FBD. :eek:

RE: Old O.S. .61 SF
 

Here are the stock numbers and list prices of the parts you asked about:

OSMG4945 27803000 CYL & PISTON 61RF ABC $114.99

These parts can be ordered through any hobby retailer who sells O.S. Max engines and accessories.

RE: Old O.S. .61 SF
 

I acquired an OS .61 Gold Head Special Addition used engine with an 86 carb. This carb is unusual in that it has the idle adjustment similar to the 7L but it has two fuel nipples. One by the high speed needle which is the normal location and one at the base of the carb near the throat of the crankase. This nipple is blocked off with a piece of tubing with a bolt in it. No piston ring on the engine so I guess it is an ABC.
I wonder if anyone knows the purpose of the second nipple and what makes it a Special Edition?
Thanks.

RE: Old O.S. .61 SF
 

Can a newb jump in here??? :)

That second nipple sounds like a pressure tap, but I could be mistaken.

RE: Old O.S. .61 SF
 

That carb is off a pumped engine. The second line is a return line, and
returns excess fuel back to the pump. It acts as a regulator, in that it
keeps the fuel pressure more or less constant, rather than having the
changing pressure effect the mixture setting to any great degree.

FBD. ;)

RE: Old O.S. .61 SF
 

Thanks.

RE: Old O.S. .61 SF
 

The inboard line is actually a line that senses carburetor vacuum. This will then adjust the regulator in the pump to change how fuel is delivered to the carburetor. When the engine's running low enough, it causes the return line to open and return fuel to the tank.

RE: Old O.S. .61 SF
 

I suppose you are referring to a built in pump. The engine I have does not have one. Would the carb be suitable to use with that nipple closed?

RE: Old O.S. .61 SF
 

Bax might know better than I on that question. I would say yes, it might be
OK if you have good fuel pressure from the tank.

FBD.

RE: Old O.S. .61 SF
 

Guys

If it's torque you want, not speed, try an APC 13x7 on the 61SF. I run one on my ringed SF using 10% nitro & the engine just loves it. I would recommend this prop for your LT40 on floats if you just want more torque. Also the low pitch gives good acceleration ( handy in the water ).

Cheers

RE: Old O.S. .61 SF
 

I would think that a 12-10 or so would cause the engine to be at a higher torque and speed. Did you mean thrust?

RE: Old O.S. .61 SF
 

The type 86 carb was designed to run with pumped engines only.The throat is too big to draw fuel on carb suction only.
On the 61, you could probably use a perry pump in conjunction with the type 86 carb.
Incidentally, you can run the 86 carb successfully without using the return line from carb to pump--just blocking it off works.
You do get a bit more excess fuel spitting from the carb inlet though at low throttle.
I have used the type 86 carb for years on a variety of big 2-strokes,in conjunction with an RFP/SFP or Hanno special pump, (Irvine 150,ST2300,MDS148,MVVS160,0S 160), for F3a competition use,and it's just brilliant- always more power than the stock carb, and once set, it can be forgotten for months at a time.

RE: Old O.S. .61 SF
 

I sold two OS RF .61 engines with the 7M carb on them. I accidentally sent them with 7L carb instructions because that's what was in the box. The buyer wants to know if anyone has the 7M instructions on how to set the carb up. I forwarded your cursory explanation of tuning the mid range, just wanted to know if anyone could make a copy and email it to me or use snail mail on it? Thanks either way.

RE: Old O.S. .61 SF
 

Hi Dave,
Is that a ten year old 61-SF - vow.
I have brand new engines that dont look half as good[&o]

RE: Old O.S. .61 SF
 

I'm with Dave in that moving up to a .60 on a trainer with floats isn't a bad thing. I've sure found that the addition of floats really impacts performance, and that having the extra power available makes for shorter takeoff runs (added margin of safety).

Dave - Jaka is from planet earth. Sweden is just on the other side. Europe is really cool. I encourage you to try it! :^)

BTW. the .61 SF is the BEST running engine I've ever owned - what a great carb!

RE: Old O.S. .61 SF
 

Glad someone likes the SF, I have two, what prop do you use? I don't seem to enjoy mine as much. The FSR and FX seems to wind up better, so I assume the SF is a stroker and wants more load than winding up? I've tried 11X7 and 12X6. What makes your SF run well? Also, plug and fuel type?

RE: Old O.S. .61 SF
 

Yes...the 61 SF is a long stroke and is happiest if you prop
it in the mid 11K range. Mine did 11600 on an APC 12 X 6.
I removed the baffle from the stock muffler and it did the
same 11600 with an APC 12 X 7.

This is the combo I use on my Ultra Sport 60. CP 15%
fuel and OS 8 plug. Absolutely terrific running motor.
Wish I had another one.

Mike Hammer

RE: Old O.S. .61 SF
 

Xtol, it's a small world, I have four Ultra Sports, 2 are 60s and 2 are 40s. I keep a 60 kit around to copy any pieces I would need to remake. Two Ultras have retracts, one has the exhaust pipe running inside the fuselage, an OS RF .61 shown. the SF I'm using a 12X6 and I'm not really thrilled with the performance of the engine. I'm leaning towards a Rossi .61 instead. If you want my SFs (two are here), pm me. I think the Ultra Sports are one of the best flying pattern planes around. I have no idea why they discontinued them.

RE: Old O.S. .61 SF
 

---------------


I just bought half a dozen or so .61SF ringed engines and one ABC w/pump (what the heck).

I get a kick out of these engines and how they will pull a heavily painted Kaos 60 straight up running a stock muffler as though the model isn't even there. Sometimes it is nice to do things without screaming at 14k rpm. <G>


Ed Cregger

RE: Old O.S. .61 SF
 

I had a couple of the .61SFs, one ABN and one ring. I sold the ABN version, but still fly the ring engine every now and then. The best prop I have found is an APC 12-7. I didn't check rpm, but it flies every plane I have had it in better than any other prop.

RE: Old O.S. .61 SF
 

Turns out this second hand engine had the wrong needle valve in it. Replaced that. Runs much better. I replaced all my OS engines for the more stout Webra Speed .61 and Rossi .61 engines sitting in the closet. What a difference. Even Morris Hobbies has a nice Mark .61 ABC with pipe and header for $150 shipped. OS's premium price just doesn't seem to hold a candle to true performance engines. I'm glad the resale value was in my favor in making the change over.

Greetings,

I am looking at these older posts trying to troubleshoot erratic idle for an OS 61 SF (7L carb) I recently purchased. I assume the attached picture showing the notch towards the high speed needle is correct. Is there a way to make sure the mixture valve itself is in the right orientation and not rotated 180 deg as BAX said could happen and would give problems? I looked on the OS website http://www.osengines.com/parts/xr27781000.html and it shows a picture of the mixture valve for an 7L but I doesn't look right and is pictured below. Mine looks like a tube with a notch or hole in it. Does the "hole" in the mixture valve go towards the cylinder or forward towards the prop? Hopefully this will clarify future questions about the 7L mixture adjustment which is made by the upper concentric screw only. Clockwise is lean, counterclock wise is rich, and the notch being vertical is the midway point.

Thanks - Greg

http://www.osengines.com/parts/images/27781300.jpg

Here's the carb manual that has an exploded diagram. The little slit faces towards the propeller.

[ATTACH]2124532[/IMG]

I just learned that the SF61 ring is the same as the one for the OS 55 HZ-H.

I own 3 OS 61 SF engines, two ringed and one ABC
No problem with the linner at all ,on the ABC engine ,which i attribute to the fuel i use ,Morgan Omega 15% ,and never run the engine lean
i was only flying for a short time,when this series of engines was release by OS (early 80's )
I got one early on ,so i have been enjoying this engine for many years
A long stroke engine ,not an RPM engine ,so more torque
I cannot say enough about how much i enjoy running this series OS 61
Engine is supper user friendly and puts out real good prop turning power
I run all my glo engines on the same fuel and a K&B 1L glo plug
I run a 12/6 apc @ 12,600 RPMs ( max on ground ) on my 60 Sig Super Cahos
This is one of those glo engines that is --just better than it is supposed to be

I have a 91 FX in my 60 Ultra Sport
That 91 is in a 60 size case ,so its light ,a strong choice for many 60 size performance airframes

Both the 60 Super Cahos and the 60 Ultra Sport --fly on rails , at a bit over 1/2 trottle ( at a fast crusie speed ) ,and have unlimited vertical ,with the other 1/2 throttle

Pictures of both the above planes are in my -Gallery , to the left of this post

Enjoy