I picked up a new K&B .20 on Craigslist today and in the box was what looks like a 4-stroke carb. It looks to be about right for a .40 size 2 cycle. I have several Saitos and they are my only experience with 4-strokes. This one does not match any of them - smallest I have is a fa-72. And none of them have the recess this one has in the machined area for the bolt holes. Can anyone help identify this?

Hi

That looks like a carb to an OS FT 1.60, could also be the 1.20 or 300. No markings on mine either. Could also be off the ASP copy of this engine.



Vince

That looks like a Thunder Tiger carb to me. The design of the fuel inlet and the throttle stop screw looks the same as the one of my GP 42.

I would have to disagree, how would you explain the 2 holes that are used to mount the choke, (4 Stroke) and hold the carb to the engine?

Vince

Would definately agree with Vince as the mounting pad along side the venturi is most likely for a manual choke making a strong argument that this is off an older four stroke and do note that hole in the side of the venturi with the adjustable screw blocking definately makes this a bleeder carb which makes a strong case for many older four strokes.

Nope have no clues as to what its off of but heck everyone loves a mystery

John

I didn't say it was a GP 42 carb. I said the fuel inlet and throttle stop looked like the one from a GP 42, indicating TT as the manufacturer. Maybe it's a carb then from a TT four stroke?

Well, looks like it is an O.S. afterall. It is for an FT160.

http://www.osengines.com/parts/images/46181000.jpg

Listed here at the bottom of the page
http://www.osengines.com/parts/xr36100.html

It is so small though. Here are a couple of pictures of it next to my Saito 120. The throat is half the size. Is that possible?

Turns out, the FT series are twins.  That explains why it is half the size of a 120 Saito.  It only needs to be big enough for one cylindar at time.  Mystery solved.  Thanks guys!

Actually they both fire at the same time, so the carb does feed 1.6 cubic inches per intake stroke, however, the OS 1.60 is not a power house so the supplied carb is fine. It is also desinged to run without muffler pressure, furthering the need for a smaller carb.

That's good to know Jeff.  Thanks for the comment.