Hi,
Been in this hobby for over 40 years and the only rossi engine I owned was the .81 for the byron f-16.recently got a box of engines and found a rossi with a black head side exhaust no carb about .40 size but also see there is a .45 .no other markings except for the cast rossi running vertically on one side.My question is how do you tell the displacement on rossi engines?

Err... Well... i don't know how to tell.[:@] There's nothing stamped on them anywhere? You could measure the bore and stroke and calculate 'em. A set of calipers and a 1/2 hour would probably get you a better calculation than what is printed on the box.

Bill

I should add that the modern Rossis I own, to include a .53, .61, .65, and .91, all have the same carb. I would be very surprised if the .40 and .45 had different carbs... even back in the day....

Bill

I've had the same type of problem, on an engine bought thru the mail. The only solution is to remove the head and measure bore and stroke. You do not need thousand of inches, the displacement .40 and .45 are enough far apart. The head removal is a good opportunity for an inspection for cracks.
As far as carbs are concerned, for sure all .40, .45 and .53 share the same carb.
Good luck!
Beppe

I bet a Perry carb would work well.

The old Rossi you have with a black head is a 40. It was one of the more powerful Rossi 40s. You can get parts for it here. It uses the same carb as the newer 40s of 3 port design.

http://shop.vendio.com/RossiEnginesUSA

Thanks.measuring the bore and stroke was my last resort.The carb opening is huge .I tried to see if a carb from a kraft 61 would fit and it is more than a little loose.I imagine that this will be a real fuel burner.I think a perry may be the economical solution if they make one for it.

Go to the site I gave you and you will find a lot of different Perry carbs for the engine and 2 Rossi carbs . He sells enough different carbs that you will have to research his info to decide which you want.

Denis

Both the Perry and the Rossi carbs work well but the Perry carbs are about half the price.

The hole in the case might be huge but I don't think the bore of the carb is. 7mm comes to mind. That's fairly conservative. Still, a strong motor needs fuel to go.

Bill

The hole in the case is 16 mm on all of them. The Rossi carbs ID is 8mm or 10mm. The Perry carbs that fit go down to well below 8mm.

Denis