Can someone out there provide me with a copy of the manual for a 61, mainly I'm looking on the carb's adjustments. I been to OS website trying to get info on the 7L carb, like I did for a 4D carb, but to no avail. I'll mail anyone a self-addressed envelope, with postage of course, for a copy of their manual. If you can help me out please e-mail me at

[email protected]

Thanks in advance.[8D]

Loosen the center allen, and turn the top screw to the 12 o'clock position.
( Straight up ) Turn the main needle out two turns.....

....it will start....and you will be pleased with the way it runs !

Adjust the top screw left for lean, and right for rich.

Shoot, that sounds easy enough! Thanks FD.

........the top screw (concentric ) is the low speed adjustment.

The center allen is the "lock"....the lower screw is only a guide.

I played around with a 7M once which looks the same and if I remember right the top screw on the eccentric adjusted the midrange and the bottom screw wound that plate in and out which adjusted the idle mix. The centre allen screw didn't need to be loosened.

Hmmm...[X(]

OK, getting a lit' difference in advice here, which is good really. Anyone out there that has an actually OS manual on this carb, can you settle this. I still would like to get a copy of a manual for this motor. I got it off an ebay sale, motor is brand new, never started, I'd like to get as much hard info on it as possible.
Thanks again to all that offer help.[8D]

Don't be confused....the 7M is a different carb. I pictured the 7D. Set the screw
in the middle....

( Hi Brian )

Dave.

The last thing I need right now is a carb with a midrange adjustment! I'm having a hard enough time learning to adust a OS 4D carb, I'm not use to having idle adj affecting the highend. [:@] And I'm also playing with a Tower Hobby 46.
I'm alearnin' though.[&:]

The O.S. Max #7L carburetor does not have a midrange adjustement. Just a high-speed needle and and idle mixture control.

The socket head screw in the middle of the carb only holds the steel yoke onto the mixture control assembly. There is no adjustment. The steel yoke has an oblong hole in it that keys to the mixture control assembly. The socket-head screw just holds the yoke on.

The hex-head scew at the bottom keeps the mixture control assembly from falling out of the carburetor. There should be a small steel washer between the carb body and the yoke with the head of that screw in contact with the steel yoke.

The eccentric-head screw at the top adjusts the idle mixture. Turn left to richen the idle, right to lean it. It doesn't take much movement to affect the idle mixture. That screw rotates from 9:00 o'clock to 3:00 o'clock. 12:00 o'clock is the starting point. Usually, it winds up at the 1:00 o'clock position or so when the engine's been properly-set. That assumes that the high-speed needle's set to just rich of peak RPM.

If you send us an email directly, we can email back the instructions for the O.S. Max .61 SF, which includes the instructions for setting the O.S. #7L carburetor.

Downunder is correct, you do not and don't want to losen the allen screw! I ahve this engine, one of OS's best.

Ah...OK...it seems the 7L (which I presume is what you've pictured and not the 7D?) is a simplified version of the 7M that I played with so it doesn't have the mid range adjustment. For some reason the 7L is missing from the carb manuals at http://www.osengines.com/manuals/index.html

The problem with the carb on the engine I was given to try to sort out was that the yoke had been fitted upside down. The flats that key to the spray bar to rotate it are set at an angle which meant that the metering slots were out of alignment so it was impossible to set the idle mix. Never having seen one of these carbs before it took a while to figure out

Yes, Brian the 7L....the 7D is the big carb from the FSR series.

Pic #1....The lower hex head holds the assy in the carb and acts as a guide.
The allen fastens the arm to the center portion, and my mistake....it doesn't
have to be loosened. The top screw (concentric) when turned left or right
moves the arm which is fastened to the center brass portion by the allen
Rocking the center brass piece left or right makes the adjustment.

Pics #2, 3, and 4 are the 7H carb, which is similar to the 7M carb. I have
never seen the 7M....but I have most of all the others on OS engines. This
is one of the few with the mid-range adjustment....the only one I have. This
one has a strange throttle arm on it. I think it was a helo engine, but I'm
not sure.....it's on a ringed .61 FSR engine.

The model 86 carb is another variation....for the pumpers.

The O.S. #7H carb was originally a heli carb, but was also on aircraft engines, and does have a midrange adjustment. The bottom screw moves the idle mixture assembly in and out to adjust he mid. Like the idle mixture adjustment, it doesn't take much of an adjustment to affect the midrange.