OK guys I will try to keep this short. About 10 years ago I bought a Rossi .45 with a tuned pipe. I liked it so much I bought another one. I had carburator problems with that one. Anyway I found a carb off of a .46 os max fx. I mounted it to the Rossi and it seems to work ok, except when I am flying I will point it at the sky and as it is climbing it loses rpm's almost like it is lean BUT I have a good vaper trail coming out of the pipe almost like it is rich. I have noticed this problem recently with the first Rossi I bought. It has a stock Rossi carb on it and I don't really remember this being a problem before. I am running 15 % wildcat fuel. Any advice would be appreciated. Thanks

Too much Nitro???
Beppe

Definitely too much nitro...no more than 5%...also put the head shims in. They were designed to run on FAI fuel. Carb is OK.

Mike

Hi!
You can not set the engine from the smoke trail! Setting should be done by ear!!

The engine is set by ear. Having said that, when the engine is in vertical flight there is a noticable vapor trail as the engine is sagging.

Hi!
As has been said earlier...15% nitro is too much! Rossi engines are set up to run on 0-5% nitro. Using higher percentages requires a 0,1mm head shim or two.
Also use a 8-10 oz tank, No bigger! Preferably set up with Uni-flow (two clunks).

Just curious as to why the Rossi would need to be set-up using Uni-flow?

The majority of suggestions makes me think perhaps I am using to much nitro. In looking at the manufactureres suggestions (instructions for everyone else) last night, they do say to run no higher than 3%. I got some 5% but the winds are really howling in Kansas today so I haven't had a chance to try it. Thanks much for all the help. I will let you know how and if it works.

Pipe could be too short for the prop being used.

Smackie,


Solve the nitro issue first...

But the tuned-pipe is hardly a 'set and forget' endeavor as well.
Once you had set the length to suit a certain prop and fuel combo; changing something, or even a change in the weather, could make it necessary to readjust the length again.

I am not sure if the Rossi pipe is a cone-and-disk design, or a dual-cone design; but the later is less critical and the former very critical in this respect.


Earlier Rossi carburettors had a throttling issue, with the mid-range being way too rich...
The OS carburettor that you now have is too small for this engine and the top-end could be compromised.
It also has a richer than necessary part-throttle.

How early?

As most Rossi carbs are based on the Bodemann twin needle design these mid range issues were easy to tune away with some simple rework of the low speed mixture needle.

Was the issue more involved than the tapers on the low speed mixture needle?

All the best,

Konrad

how did you manage to fit an OS carb on yur 45? i had to shim the hell out of an OS carb with some aluminum soda can strips and silicone sealant

Quote:

ORIGINAL: MetallicaJunkie

How did you manage to fit an OS carburettor on your .45? I had to shim the hell out of an OS carburettor with some aluminum soda can strips and silicone sealant.

MJ,


All that's needed is a split collar to 'thicken' the spigot diameter, from 0.5" (12.7 mm) to 16 mm.

No need to use many soda can strips for that, or even silicone RTV...

Way to much nitro. I had the same engine and never had a problem on 5%, a little demanding to tune with the pipe but a real runner!![:@]

Actually the carb pretty much droped right in. Pretty good fit.

havent seen you in a while Dar...are you doin better?

Quote:

ORIGINAL: MetallicaJunkie

Haven't seen you in a while Dar... are you doin' better?

MJ,


I'm OK. Thank you for asking.

But I have not been totally absent, you know.
Please look back.