I recently got an ASP 25 in a bunch of engines that I bought. I was about to toss it into my junk box, when I thought "maybe worth a second look". I cleaned it up and replaced a missing head bolt. H'm not bad, plenty of compression and no obvious rod or bearing problems. I made up a venturi for it, using LA 25 S inner dimensions and used an OS NVA. This ASP 25 had a pinch bolt retaining system, so not a drop in venturi replacement.
I then put it into a Flite Streak, after removing an LA 25. I used an APC 9x4 and the tank etc was straight BBTU set up, except I used the ASP silencer. It ran like a good un, if anything a bit more power than the LA25, but who is bothered about minor things like this?
OK ASP may not have the OS reputation and the ASP 25 is a tad heavier although it looks like a ball raced engine (although it has not been stripped down to check this) and it is a real ABC, not the OS nickel coating. Thinking about it, the LA 25 is no great shakes in the quality of materials stakes.
ASPs (Magnums etc are the same thing) are cheap to buy and seem every bit as good as an LA 25.
If anyone else has one, might be worth a try, if they can make the venturi. The ASP 25 is still in production, so if it is as good as I think (confirmation would be good!), then we have an LA25 replacement, which is still made.

Andrew.

What little I've run it I sure like my Magnum 35.  I suspect an ASP/Magnum/Whatever 25 would work pretty well.

First off, i love magnum and asp engines. But what about the k&b 28 from county line hobbies? It says it's 7.2 oz. The Fox 35 was 7 or 7.1 oz. What little experience i have with these k&b sportsters is that they are extremely powerful.

http://www.countylinehobbies.com/kb28colien.html