howardh

My Feedback: (22)

I bought a new Rossi 40 Sport from a club member. At least I think that's the motor model. He said he changed the carb for better performance. I'm skeptical about that, but I got a steal on it and I'd like to know what I have. There are no markings on the at all. IIRC he said it was a Webra. I searched Webra, found some diagrams and they looked identical to me. So I emailed Webra in Austria with a pic of the carb and they answered it was "not of Webra origin". So, perhaps one of the experts out there can help. If it helps the intake diameter is 8mm and the mounting diameter is 15mm.
Also, can anyone help in the exact model of the motor?
All answers and help is greatly appreciated. Thank you all.

Howard

rambler53

My Feedback: (494)

I'm not an expert but it looks MVVS to me. It probably is a great carb match for that engine too. Try it and let the tach tell you. Nice engine. Nice carb. R40 FI

http://www.mvvs.nl/MVVS/images/3216_2.jpeg

http://www.mvvs.nl/MVVS/images/3219_2.jpeg

asmund

Definatley MVVS, I have a couple of those

rcdude7

My Feedback: (264)

Looks like the latest model MVVS carb, probably works better than the original rossi mixer.

howardh

My Feedback: (22)

Thanks Rambler53 and Asmund. You hit the nail on the head. The pics you sent and others that I've found, now that I know, are identical. Better yet it's good to hear the carb and motor should be a good match. As soon as I finish the plane, a Strega racer (just for fun) I guess I'll find out. Got to break it in first though.
Is there a difference between the R40FI and an R40Aereo? Is my motor a regular sport type or a so called racing motor? Any links you know of to specs on the motor?
Again, thanks for the help and quick replies.

Howard

djlyon

you have to look inside to see if it is a 5 port or 3 port. If it is a 5 port it is some kind of a racing engine but you still don't know which kind.

Denis

Konrad

That engine was always a sport engine by Rossi standards! And a very fine sport engine at that. Now as for the carb, top end performance is derived by the size of the choke area. The bigger the choke area the better it will breath at speed. What really defines the suitability of the carb to the engine is how well the mid range mixture profile is matched to the airflow at lower speeds and throttle setting. This is why carb designers use so many different low speed needle profiles (on true twin needle carbs) or fuel discharge ports on tube over slot carbs.

As I recall that the Rossi 40 came with a small carb 8mm bore. The reason it ran so fine (powerful) on such a small carb was because of the large dwell angle afforded by the 17mm crankshaft. This link might help some understand crankshaft dwell.
http://www.rcuniverse.com/forum/fb.asp?m=9958733

This crankshaft is why it ran so fast on a 9x7 prop and could still out pull most asian 60s on an 11x7.

You might also find this link helpful
http://shop.vendio.com/RossiEnginesUSA/category/1/



Konrad

Broken Wings

My Feedback: (20)

You can buy the correct carburetor for that engine for $105 or the entire engine with muffler for $120...?...

http://www.hobbyclub.com/index.php?c...39bb7683bcca58

Konrad

Wow, that is a great deal. Real bearings, real ABC P&L, a full size crankshaft, and a super flexible engine!

I think I paid close to that in the mid 80's and that was with real dollars! Well more real than what we now have.



Konrad

Broken Wings

My Feedback: (20)

For the carburetor or the engine...?

Konrad

OK, after reading the link posted to Hobby Club I have to down grade it to a good deal (value).
In the 80's one got a muffler of sorts with the sale price. Still mama Rossi puts out far more power than even most asian engines that are 20% larger in displacement. Also the engine itself is far more durable at elevated power levels. And because of the larger crankshaft and bearings it's more tolerant to impacts (ditch digging[X(] ).



Konrad

Hobbsy

My Feedback: (102)

The carb on the left is an MVVS 7mm carb, yours appears to be larger. If you need directions for that carb, I have them, they are precise and when followed make the carb setting easy.