What is this engine?

[Rick Bollinger]

Can someone tell me what I have here? I got it in a box of stuff several years ago and have no clue of size, make or intended use.
It has been ran, a little gummed up, but looks to be in fair shape. It weighs 7.2 Oz Thanks Rick

[Larry Lindburg]

My guess is a Fox 25 BB or a Fox 19 BB.

[dennis lipsett]

My guess is a Fox 25 BB or a Fox 19 BB.

Larry, your right. These are among the best engines that Duke ever made. I'm not talking stunt wise but they are potent and durable. The 19 was capable of keeping up with most of the 21's available in the early days of R/C Combat easily flying a 36 inch VooDoo type wing at over 86 mph on radar.

dennis

[john e. holliday]

Yep, that looks just like he Fox .25 I am braking in.  It is going to power the Estes Stuntin Ringmaster I am finishing up.  Great little engine on the bench so far and starts very easily.

[Chris Wilson]

Yep.

[ChrisSarnowski]

More likely the 19bb and not 25bb, but to be sure you would have to measure bore/stroke.
The 25bb usually has 25BB stamped on the right mounting lug as you look at the engine from the front.

The 19bb has bore .650 stroke .600 while the 25bb has bore .680 stroke .680

I have the same old engine as you which I believe to be the 19bb. The gas passage in the crank is not as large as the 25bb.
I noticed this when I pulled the back plates off both my 19bb and 25bb.

-Chris

[Rick Bollinger]

Thanks everyone, Got out the dial indicator. I have no way to keep it completely stabilized but it is definitely closer to .600 than .680. So it must be a 19. Now just to decide what to put it on.

[Clint Ormosen]

More likely the 19bb and not 25bb, but to be sure you would have to measure bore/stroke.
The 25bb usually has 25BB stamped on the right mounting lug as you look at the engine from the front.
.
Chris

Haven't noticed this, Chris. I have 2 of each displacement and none of them are marked. In fact, I've never even seen one marked "19" or "25"..

[Randy Cuberly]

Thanks everyone, Got out the dial indicator. I have no way to keep it completely stabilized but it is definitely closer to .600 than .680. So it must be a 19. Now just to decide what to put it on.

It will fly a Ringmaster quite nicely.  Or anything in that size/weight range.

Randy Cuberly

[ChrisSarnowski]

Haven't noticed this, Chris. I have 2 of each displacement and none of them are marked. In fact, I've never even seen one marked "19" or "25"..

I don't think they ever marked the 19BB but at some point they started marking the 25BB.

See the attached picture, now you have seen one marked 25BB !!!! (sorry if it is a little blurry).

Measuring bore/stroke is the best way to determine the size of the unmarked engines.

-Chris