OS 61RF-P and Rossi 61
 

Hello Everyone

Last week I ran the OS61RF-P with the new piston and liner. It didn't go so well.

When I got the engine and pipe I also received a aluminium backed plastic spinner and 3 APC 12-11 props. The 12-11 prop is the maximum recommended prop in the instructions. I may well run this prop on the beetle so for break in I found an APC 11-11. I fitted the prop and spinner and then heated the cylinder gently with a low watt heat gun to take the really tight nip out of TDC. I then fired it up and allowed it to warm up a bit.

When I got it to full throttle opening it all started to go astray. The engine was surging so bad i couldn't get a tach reading to know where to go. It was running between about 8k and 12k. During the surges heaps of smoke was puffing out of the pipe. Then at the end of one surge it spat the prop off. At that point I put it away to think about what went wrong. The prop was stuffed and so was the spinner.

Any ideas what was wrong. My gut instinct is that the pump regulator was sticky and pumping too much then too little and it went lean and detonated.

Today I put a 12-9w on and it ran fine. I ran it on the rich side of things and got a peak at 11k. As the engine ran more throug the tank it got up to 11.4k It also had a nice reliable idle at a bit over 2k with pretty good transition.

I will do the rest of the run in and tuning in the airplane.

Next on the list of engines to run is a Rossi 61 rear exhaust. I have no details of the ideal prop as I have no instructions. Can anyone recommend the best prop and RPM target for this motor.

Cheers
Tarquin

RE: OS 61RF-P and Rossi 61
 

best easy to find prop for the rear exhaust short stroke rossi; apc 11\7...
target rpm 14500 rpm on the ground with the rossi dedicated header and tuned pipe.

RE: OS 61RF-P and Rossi 61
 

On the OS RF-P initial run: It sounds to me like it loaded up on you...Do you remember where the needle was set?? My experience is more than one turn out will be rich...I usually start with one turn plus 3 clicks and adjust from there...I'm sure it will vary with different pipe lengths and atmospheric conditions but I would think the maximum would be about 1.5 turns out...

It seems the second run with the 12x9w went well...The tachometer numbers around about right so I'd say she seems to be running good... :D

That engine should be very easy to fall in love with...They handle like a charm and are very smooth and consistent...Really read through the Hanno manual I sent you to set up the tuned pipe because there is some great information in there....I personally like to set the pipe up a little "conservative" rather than on the razor's edge of performance...I like to have a nice broad needle valve range (two or three clicks between lean and rich)...If the pipe length is set for "max performance" you will notice the needle valve becomes very sensitive (ie: one click between lean and rich)...If the pipe is too short the needle valve may become "un-responsive" and the engine may sound "tinny" which is not a good thing...

Have Fun...

Chuck

RE: OS 61RF-P and Rossi 61
 

I'd go with what Daggets said, but would use a Rev-Up 11 - 7 1/4. Back in those danged good old days, we'd never dream of a 12/11 or a 12 anything on .60. My Rossi's (side and rear exhaust) w/ Rossi pipes consistently pushed 14K rpm without a worry, on 10% nitro too. 1980 Nats, Bootlegger, Cool power, what a blast it was (even w/o the blonde I met). Enjoy.

mk

RE: OS 61RF-P and Rossi 61
 

Thanks for the replies guys.

Sorry for late response. I have been away from home for the last week or so.

I wasn't sure if the Rossi was a motor for luggin or revving. When I mounted it to the test stand the pipe looked way shorter than the (conservatively) long pipe on the RF. This was the first clue it would probably like to rev. I guess the Rossi will be similar to the OS61VF. I will start with the 11-7 and see what I get.

I will report back when I get some results from the test stand.

Cheers
Tarquin

RE: OS 61RF-P and Rossi 61
 

Hi Tarquin,
I'm running an APC 12x9 on my OS 61VF with very nice results. It is in an MK Silent 90 which has nearly unlimited vertical, very fast horizontal and is very quiet compared to the screaming 11x7. I'm using an old Hatori 605 pipe. Generally, you can run a wide variety of props, but you will have to adjust the pipe length accordingly.
Good Luck,
Will

PS Regarding the Nelson piston/sleeve - I agree that you were probably too rich - also, Dave Shadel's instructions (from 20+ years ago) indicate that initial break-in should be without a glo-plug, some good oil and 40-50 rotations by hand before actually starting the engine. I usually use an apc 12x10 for break-in (of Hanno Specials). I prefer the APC 13x9 on my current Hanno flying in an MK Super VR-90.

RE: OS 61RF-P and Rossi 61
 

The O.S. Max .61 SF or RF engines (pumped or not pumped) should be propped so that they turn in the mid- to high-11,000's when leaned to peak RPM on the ground. They are not really ported for turning lower RPM. The Hanno was ported to turn in the mid-9,000's when used with the appropriate tuned pipe and an APC 12 x 12 prop. The SF/RF series were not for such low RPM, although many people tried to run them that slowly.

With the pumped engines, you want the needle no more than 1 turn to 1-1/4 turns out from closed. That will be super rich. Once started, open the throttle to full and lean the engine. Lean it as far as possible without detonation or RPM drop and LEAVE IT THERE! DO NOT RICHEN FROM THAT POINT! The pump (when operating correctly) will keep the mixture at the proper amount. Surging usually means it's too rich. Once you start flying, listen to the engine carefully. You'll need to fine-tune the mixture to suit how the engine unloads in the air.

Use a fuel with no less than 18% oil content. The non-ringed engines should have about 50% of the oil being castor oil. If you have the ringed versions, then an all-synthetic oil will be OK.

The VF-series engine mentioned above should be propped to turn near 13,000 RPM when leaned to just rich of peak RPM on the ground. They were intended to turn higher RPM, and were great for the ballistic pattern types...lousy for turnaround.

RE: OS 61RF-P and Rossi 61
 

Hi everyone:

I have a Rossi 61 with a perry pump in the back. Supposedly the engine was un-tunable and thus I ended up with it.. I have the rossi header and its tuned pipe.

I dunno how that pump works but the engine hadn't been turned on in over 20 years.. It was in a MK Joker and will go back into it.

So after a bit of un-assembly and lots of wd-40, mystery oil it loosened the engine. I cleaned it and put a bit of regular glow fuel from one entrance to the other in the pump..

Cleaned the carb and put in in my test stand and that thing fired up in the first flip of the hand a bit of tweeking and that engine was screaming like a banshee Insane RPm in high speed and awesome idle, you can allmost see the prop stop and go again.

Question about this pump.. how do I use it? Is it necesarry and how do I set it up correctly? I did notice a slight crack going inwards in the pump back side which is inside the engine is that normal??

RE: OS 61RF-P and Rossi 61
 

This post by Bax is one that every classic pattern enthusiast should save to his/her hard drive for future reference.


Ed Cregger

RE: OS 61RF-P and Rossi 61
 

Show us a picture, Night Scream.

If it is running as good as you say it is, of which I have no doubt, why mess with the pump? IIRC, the OS pumps had no user adjustments anyway. True?


Ed Cregger

RE: OS 61RF-P and Rossi 61
 

does the rossi have the stock 8MM carb or a larger perry carb?, if its the perry carb leave the pump on...and the perry pump has a nu/screw in the center of the pump, out for less fuel pressure, in for more fuel pressure, the rossi will accept without any mods the new AXE/ROSSI 10 mm carb, it will also perform well without pump, simple pipe pressure will suffice!, i tap the edge of the header plate and use a Mac's 8-32 pressure tap, it works every time, i have burnt more than 300 gallons of fuel flying rossi 60/61 engines

RE: OS 61RF-P and Rossi 61
 

The rossi has its stock carb.. I ran the engine today in my test stand for 10 min with a cool down of 10 more.. and ran it 3-4 times today in the flying field.

Engine has very insane high speed and now very good idle and worked perfectly in all positions [upside down, side ways, tilted] can't wait to put it back int its plane and fly it.

Um about pictures I still have trouble setting up my digital camera so for now sorry no pics of the engine :(

RE: OS 61RF-P and Rossi 61
 

hows the plug life on it, if its popping plugs add the second shim and enjoy, they should last many flights it if the shims are set right, they come with one shim in and second one in the box normally

RE: OS 61RF-P and Rossi 61
 

Tarquin,

If you want some information about the Perry pump, maybe I can give you.

Cees