bweight

Hi, I have a Rossi .81 Ducted fan engine, and I've misplaced my manual (or the small instruction sheet)... I need it for the break-in procedures, as it's not running correctly.. When I start it up, I have to be over 1/2 throttle for it to kick in. And when it does, it runs great on the high end. but I can't go below 1/2 throttle or it surges..

Now, as for the needles.. There's only 1 on the carb, and when looking in through the carb, it doesn't seem to be doing anthing, except for rotating the spray needle around the pin. It doesn't seem to adjust anything at all. There is no low-end adjustment from what we can tell, as like I said, the only adjustment controls the sprayer..

When we go down to lower than half throttle, as I said, it surges high and low, and ultimately, cuts out if I leave it as it is.. If I bring it back up, it'll run good, BUT, it ultimately won't stay running for long.

If someone has a link to the manual, or can scan it in to the computer and send it, or ANY help whatsoever, please, send it my way.. I'm trying to put this plane together so it's ready for the spring, and while I still have time, I'd like to get it ready as soon as humanly possible.

you can email me at: [email protected] or just respond to this post if you can help..

Thanks,

Brian.

jaka

Hi!
You certainly don't need a manual for running the Rossi! As with all modern ABC, ABN and AAC engines the only thing you have to do ist to start the engine and run it a little rich at full throttle opening a few tanks, controling the rpm with the highspeed needle. Its that simple!
Nearly all modern carburetors have two needles: one highspeed needle and one low speed (or idle) needle.
The idle needle is on the left side of the carb if you look at the engine from the front. Its very small, centered in the middle of the throttle arm.
It is much easier to set the engine if you put on an ordinary prop like a 10x7-10x8 APC.
Fuel could be 5-10% nitro and glowplug a Rossi 6-8.


Regards!
Jan K
Sweden

bweight

Thanks for the help..

I can't believe I didn't look in the centre of the throttle arm for the lowspeed.. I'll go check again in a few minutes as it's out in the garage right now..

I'm using an OS #8 for breaking in right now, as I don't have any Rossi plugs. I'm swinging an 11x7 as is said in the manual that I can remember, and using I think 10% nitro....

Hopefully when I run out there, I'll see what I missed yesterday, if not, then it's back to square 1.

bweight

well... sadly, there's no low-speed needle on this carburetor.. So I don't know what to think.. I'm gonna strip it down, and see what's going on..

jaka

Hi!
There must be! Rossi... haven't produced a carb without a low speed needle!
Can you show us a picture?
Here's a picture of my Webra .40 GT carb showing the low speed needle.
Regards!
Jan K
Sweden

bweight

I'm gonna apologize for the picture quality first.. my camera sucks, and so do the pictures it takes.

Anyways, I took pictures all around the carb.. it's mounted on my test block, so there's a little blockage in the views..

The first picture is looking from the side where the fuel inlet is.. There's just a solid casing, and no adjustment needle there.

The second picture is from the front of the carb. You'll see the only needle adjuster there where the throttle linkage is.. That's the only thing I can find.. (with exception to the bolt on the bottom side)

Third image shows the throttle linkage and the above mentioned adjuster... Hope this helps a little bit.. Cause I'm still stuck with this problem unfortunately.

Flyer95

My Feedback: (1)

bweight,
Thats your idle needle. So you must find your high speed needle valve ( with one inlet and one outlet pipe) it is separate from the engine and made to be mounted somewhere else like on the fuselage of the airplane. Look in your engine box, it should be there. Good luck.

bweight

Seriously? hmmmm.. i'll have to check the box.. weird.

bweight

nothing in the box.. Where does this get mounted? Do I hook it up from the fuel tanks, to the inlet on a valve, then from the outlet on the valve to the fuel in on my engine? and I adjust it from outside on the fuse if that's where I mount it?

Sounds kinda strange....

Flyer95

My Feedback: (1)

You should mount it somewhere inside the airplane where you can easily reach it with your fingers for setup on the ground. This type of remote needles are common on the DF-airplanes as it is very difficult to reach the main needle on the engine beeing in a duct.

Yes, Good luck.

Flyer95

My Feedback: (1)

Hi again,
Here are some pictures I found on the e.bay on a rossi marine engine. The high speed neddle on this engine is not of the remote type but rest of the carburetor seems to be like yours.

jaka

Hi!
The picture shows the idle needle! Not the high speed needle! The carb seems to have been modified to a remote high speed needle.
If you don't find the highspeed needle...just buy a new one and mount it where ever you want!
See my picture of the remote needle on my Great Planes GEE -BEE R-1 and my Q-500 racer.

Regards!
Jan K
Sweden

bweight

Yeah, I spoke with someone today regarding this.. It does in fact seem like it's been modified for Remote needle valve.. I should have one next week sometime. Just have to order it up..

I'm gonna get an in-flight mixture control so I can adjust on the fly I think

Flyer95

My Feedback: (1)

Bigger pictures as my previous pictures was too small to see anything, maybe some help. The carb on my pictures are not the remote needle style. Good luck.

DarZeelon

Brian,


I believe your engine is an ABC, like Jan (Jaka) wrote.

If you follow the break-in procedure explained in [link=http://www.rcuniverse.com/forum/m_1850473/anchors_1850473/mpage_1/key_break%252Din%252Ctapered%252Dbore/anchor/tm.htm#1850473]this RCU thread[/link], it will live a long, powerful and reliable life.

About the prop to use, there is a problem.

Most props will not withstand 22K+ RPM without disintegrating... Pylon props will, but they will put insufficient load on the engine.

Do the break-in with the fan unit that you intend to use.

bweight

Flyer95, thanks for the pics... Morris Hobbies confirmed that it's setup for Remote high speed, so I'm cool with that.. The thing that's bothering me is that the lowspeed doesn't seem to thread in.. It just spins. I took the barrel out, and the needle has a brass collar around it coming in from the throttle arm end when the needle comes in.. Now, when I turn it, both th needle AND collar spins. Is that supposed to happen? or is the low-speed needle siezed to the collar preventing the threads to function correctly?

DarZeelon. Are you 100% sure that it will be ok to break in with the fan on it? should I also attach the shroud or just the fan?

Thanks again for all the help guys.

DarZeelon

Brian,


First, make sure, by looking at the piston through the exhaust port, that it is really an ABC.
Many larger engines are ringed and a two-cycle initial break-in is destructive for these engines.

If you use the fan for break-in, it should be used with the shroud, or cooling may be compromised and load will be reduced. It is designed to run with the shroud.

There is no prop alternative that will both cool the engine and allow it to spin around 21K RPM...

Flyer95

My Feedback: (1)

bweight,

When turning the idle needle CW it should go toward the center of the carb throat, leaning the mixture. It is probably very lean by now as you didnt had the high speed needle to adjust the fuel flow to the carb, and thats why your engine wont run at the lower half of the throttle. Open it up few turns to make sure you are not running it lean at the lower half. If the needle wont move in any direction by turning it CW or CCW then something is wrong? try to open and pull it out carefully as it may be beyond the threads. Good luck.

jaka

Hi!
First You have an ABC engine. No modern Rossi has ever used a ring.
Second I would advise you to put on a 10x8 or 11x7 wood prop for running in. The Byron fan could of course the be used but as this is a pusher fan, all air is going forward so the engine gets no cooling air if you use it as it is.
As for the idle needle...the idle needle on the Rossi carb is fastened just as on all other engines:
It screws in! If the treaded brass liner is spinning with the steel idle needle something is wrong.
Regards!
Jan K
Sweden

bweight

That is in fact, exactly what is happening with the idle needle.. I'm going to pull it apart and see if it's seized.. I gather I'll need a new one, but I guess that's better than needing a new engine

Got my hands on an in-flight mixture control now too, so this weekend, we'll give it another go.

DarZeelon

Brian, I admit that I did not think of this, when I suggested to do the break-in with the fan...

In this case, Jan is absolutely right and a rigid wooden prop is the only type that would not fail at these RPM levels.

However, a 10x8 (Zinger or TF) prop will absorb 5.28 HP at 22,000 RPM, which is beyond the capability of this engine. The 11x7 would be even worse (6.77 HP).

A 9x8 could be fine, at 3.47 HP and is even less likely to fail.