wessman

Hello!

Whatīs wrong w/ my Rossi 53 carb when I turned the hi-speed needle out it just doesnīt become rich - at least, I couldnīt hear any difference? Few days ago I leaned it and sometimes I richened it and it followed what I did but today it didnīt respond when I turned it out. I have already put 1 litre of fuel thru it (just finished braking in) and itīs equiped w/ mini pipe and 10 x 6 prop - just if it makes any difference to your opinion. Anyways, Rossi idles, transits and runs very nicely but the hi-speed needle doesnīt seem to respond at all - no matter wether I turn it in or out. When I pinched the fuel line it was about to kill the engine so I was about to lean or on lean. Any guess whatīs biting the carb? Many thanks in advance for your great replies.

Peter.

Homebrewer

My Feedback: (8)

Its definitely a fuel delivery problem and can be a number of things.

Starting at the carb:
Remove it and clean it and blow it out to ensure no contaminates got stuck in some of its small passages.

Check engine for airleaks, loose backplates, headgaskets, glow plugs, loose carbs, missing gaskets.

Replace fuel lines or check for airleaks

Check fuel tank lines and clunk.


Good luck, it just a little systematic and logical trouble shooting.

ZB50

Are you using pressure from the Pipe????

ZB

wessman

Yep, Iīm using the pressure from the mini-pipe. Was it a bad thing ? Some black colored s*it is moving to the tank via the hose from the pipe . Fortunately the clunk has built-in filter and another filter is b/w tank and carb. So far, the hose from the tank to the carb is clean but some bubbles come occasionally.

Thanks for the previous replies.

Peter.

Flypaper 2

Peter:
Filter between the pipe and tank will stop it. It's normal carbon in the pipe.

wessman

Think I just found the reason here in RCUniverse- it could be that my lo-needle was far too lean and that caused that hi-needle to become ineffective . Gonna try that tomorrow. Also other previously recommended thoughts I will try.

Thanks.

Peter.

Flyboy Dave

My Feedback: (21)

I'm wondering if the double fuel filters is just making
the fuel too hard to draw....

....usually it's some crap in the nozzle on the main
needle....I don't think a slightly lean setting on the idle
screw would effect the high speed to where you can't
richen it up.

Dave.

jaka

Hi!
You do run 0-5% nitro do you.......
Fuel filters belong on the ground.....

Regards!
Jan K

RaceCity

Thanks Jan....

Nothing worse than a leaky filter to screw EVERYTHING up. Filter the crap out of the fuel going in the tank and run straight lines after that.

Homebrewer is on it though....it's a fuel delivery issue. Clog, LS needle too lean, something. When the HS needle isn't responding....look elsewhere.

"Mai Penrai!!!!"

tjgorman

My Feedback: (3)

I had the same problem just a couple weeks ago, it was do to tweaking the low end and closing it off too much trying to get that low end idle just right. Low end=slight adjustments 1/8-1/16 at a time.

2 cents.

wessman

Hlo!

Checked out all screws (head and back) they were all tight, so prob wasnīt there. Found that there was no filter in the clunk too - it was in my Cool Power container, so only 1 filter was being used b/w the tank īn the carb - now there is no filter being used at all, just straight hoses. Carb was cleaned before prob came out but I cleaned it again. HS started to respond when richening that Ī%#Ī-LS completely. But now itīs quiting at 1/2 throttle (can play b/w idle and 1/2 throttle the whole day long but if I advance more it quits surely - also it rans well at full too). Maybe I should open HS a few clicks? I use 5% Nitro, 9% Synthetic, 9% Gastor, 77% Methanol. The plug is Rossi 6 - itīs a cold plug, today Iīll use hotter plugs to see any changes. Hey Mr. RaceCity, it does "PEN-RAI", hah, hah - Iīm getting this I I close to change to electric power if this &%Ī#Ī-Rossi carb doesnīt start to co-operate w/me!

Anyways, many thanks to all of you for your help.

Peter

bobi

if you are having cuts off at half throttle then fuel is not flowing in.. .. either you are lean on the high side or else something is restricting fuel flow...
changing the flow plug is good idea...may have been some damages during your break in.

i did send you a pm some time back .. no reply ...

Flyboy Dave

My Feedback: (21)

....I did a little carb snooping on my .45 carb, and was
kinda suprised at what I found. The carb works a bit
differently than an OS carb....which has a split spraybar
....and both needles can work a bit independantly of one
another.

Look at the picture....see that skinny non-tapered needle
coming in from the right ? That is the low speed needle.
The bore is wide open in the pic. When the carb closes....
the nozzle slides over the needle....and the needle goes
way inside the nozzle.

It appears that the low speed needle actually controls all
the metering....except the actual setting (or openness) of
the HS....at full throttle.

I looked at the .60 size carb, and it has the same set-up,
so I'm going to assume your .53 is the same.

Look at the pic in my next post....

Flyboy Dave

My Feedback: (21)

The strange thing is that the low speed needle is in
all the way....and backed off only 1/8 of a turn. This
carb is on my .40 size F-20, and it runs perfectly.
There are 7 threads showing above the head of the low
speed screw.

The HS was set at almost 2 and 1/2 turns out. Just for the
heck of it....back the HS needle way out....crank the LS all
the way in, and then just crack it out 1/8 turn....then turn
the HS all the way in to a lightly seated position, and back
it out 2 and 1/2 turns.

See what happens. If it bogs coming off idle....open the LS
a little at a time, and see what happens. If it will get to full throttle, set the HS normally....just a tad rich.

Use 5 % nitro and a normal plug....I hope you have some
castor in the blend....

Flyboy Dave

My Feedback: (21)

....(same as a Rossi) and the needle is cranked way
down on it too....

Flyboy Dave

My Feedback: (21)

....same thing....needle cranked way in....

....I'm thinking if the LS needle is cranked way out....

...it's running off the LS only....that might explain
the problem....

....'course, I've been wrong before.... :stupid:

wessman

Thanks again for your inputs, friends! This morning I went out to the field to adjust that God da**ed thing, and guess what, I succeeded to put it to co-operate w/me. This time I richened HS ībout 1000 RPM from the peak īn started to screw in that Ī#%"* LS (it was about 5 turns open when I started - max is 6 turns then itīd drop onto the grass). Everytime I turned that Yacky LS in by 1/4 turn till it was about 2 turns open from the closed position. There it seemed to work kindly - so far. So, now it idles, transits, and scream well - doesnīt quit nor hesitate even idling more than 30 sec, also it responds to HS, can make it rich and lean - just as the master says. Am I expert now ? Maybe me and Rossi will be good friends - itīs all upto Rossi, better not to make me mad anymore. Dave, I got exactly the same lovely carb like yours. With my luck, Iīll brake it soon now that I finally got it to work well .

Flyboy Dave

My Feedback: (21)

If you look closely at the pic in post #13....at wide open
the needle is clear of the nozzle by about 1/3 distance.
That L/S needle is set at 1 and 1/2 turns out from the
bottom. The needle doesn't "clear" the nozzle until 3/4 throttle....to full. Then it runs strictly off the HS setting.

Again....it looks like the LS controls the metering....up to
the 3/4 point.

I'm sure glad you got that baby running good. I really like
my .45, it's a screamer. I've gathered several Rossi's, but
I'm only using the one at this time.

I have alot to learn about the Rossi's as well. I picked up a
couple used .60's, and I see that the LS is cranked way out....maybe that's why they sold them (heh heh heh).

bobi

wessman
which plane you got the rossi bolted on??
are you residing in bangkok??

wessman

Hi, Bobi!

I sent you pm last day - pretty long one. There are replies. I bolted that devil on SIGīs modified Something Xtra. Last evening I got AGAIN prob w/ *Ī#% Rossi carb. Iīm gonna open a new story about it. Hope to see you.

Peter.

seanychen

My Feedback: (4)

I just talked w/ Morris Hobbies and they said Rossi just fixed the carb problem. The problem w/ the carb is that the spray bar is too long, so the idle screw cannot lean the idle enough. The new batch of Rossi 53 has the fix w/ the shorter spray bar.

The catch to this is you can't tell which version you get unless you can assure from your dealer & his distributer the one you get is from the new batch.