daggets

I have used a lot of webra, rossi and even an ops engine...
I ve even tried a nib 20 years old os 61 sf pumped, i ve bought for a big price....
I have always encountered troubles to make them running ok, some at the beginning, some, after a while...
Lately,tired of those expériences, i have fitted on my heavy curare a brand new os 61 fx, very stock, with no pump...
With the stock muffler, i though " well, its really easy to tune, but for the power, it s not even sure the ship will be able to take off..."
Then, i ve fitted the mac s tuned pipe... and then...
It is the best engine i ever had... two flip to start, never had to retune, the power is on the rossi average, but every day... with a 12/8 prop..
So, on my opinion, the simplest way for getting reliable, cheap power, the os 61 fx is a very good option for our pattern ship...

Taurus Flyer

Daggets,

After I did discover vapor lock problems as result of the needle valve mounting on the engine back plate I did switch over to MVVS, same mounting holes ABC type.
If you ever experience deadsticks, contact me!.

The OS Max is modified for that I later did hear.

The MVVS can torque a 13 x 7 propeller on my Taurus and gives very acceptable vertical performances. For me that’s more important than top speed.
When I compare the power I think the MVVS wins, but do not know for sure.
The engines are full “interchangeable”
Mounting holes, weight and even the throttle linkage.
I use both engines on the same plane, don’t have to change anything.
On the picture the two “spares”, compare prizes yourself!
I think I will use the MVVS also on my Simla.
Starting the MVVS , one back flip!!!
On all my engines I use fuel pressure controllers (like Cline) and a check valve in the exhaust/tank hose.

Cees

EDIT: On the pictures you see the OS Max 61 FX with a Moki carburettor, to solve the vapor lock problems. This Moki has an enlarged bore.

CRAPTECH

Thanks for the information on the OS 61 FX, which Macs pipe did you use and what was the length of the header? TMG

Jon Wold

I loved my 61 FX. Without a pipe it was sluggish but with a Hatori 650 it was really great. 12x9 or 12x10 props used with great success and so smooth to operate.

daggets

http://www.macspro.com/tuning.asp
all you need to know!!!
You can even compare the engine power, with surprising results!!!!!
exemple: according to the chart, the mds 68 gives the same power as the 61 fx... this one is more powerful than the 61 fsr...
in fact, as a side exhaust 61, the fx is the close second behind the rossi!!!

Tommygun

My Feedback: (2)

If you like that motor you'd LOVE a piped .91FX. Fits in the same mounting area as the .61, but .30 more cubes. Sends my heavy King Kobra vertical like a rocket ship till you pull the throttle off. In fact, I'm considering yanking my chronically irritating YS .61 out of the Tiporare in favor of the .91 setup. Very reliable....until you run them too lean! My .61FX threw a rod after a lean run with the pipe.

Steve25

To me, talking about OS, nothing came near the OS 61 FSR ABC.
Took an airplane vertical after two meter runway , while in the same plane, then SF needed at least 20 meter to take off, and the FX only gave misery
Very reliable are my Webras and my old fsr's..., and next testing some Super Tigres... .
If I only could find new bushings/piston sets for my FSR ABC...