They, along with the rest of the Sportster series engines, can be used for stunt work. They tend to run a 2-2-2 type of run. I used to use the .20, but more often, the .28 on designs like the Twister to good effect. The .45 and the .65 can be used, but they are often referred to, and improperly so, as Slag engines due to there being no cylinder liner. It's an aluminum piston running in an aluminum sleeve.

They tend to be heavy compared to most other engines, and that's the main reason more are not seen in the sport. Still, properly cared for, propped right, and fitted in a design that needs the nose weight, they can be great running, friendly engines.

I have one .20 sportster that's converted to diesel that will amaze you.

The K&B 45 makes a great stunt engine 12 x 5 prop or a 11 x 6 . If it is a little low on power take out the muffler baffle.
Willis

Leo
One of Mike Garmon’s Most famous saying was if you are having a engine problems that you can’t solve, put Fox Superfuel in it and that will cure the problem.
Willis

    Back in the days of 4-2 breaks, about 20-25 years ago, several locals got Sportster 45s. This was right after they came out (87-88?).  They ran very nicely and pretty quietly for the time, and had a whole lot of "power", easily a match for my ST46. Whether these examples were exceptions, or they all run that way, I have no idea. But it's worth a try if they aren't worn out.

     Brett

The early edition of the Sportster 45 was a real anomaly for the Sportster line.. It ran RPM levels that matched the best ball bearing equivalent motors of the day and was quite happy to also turn a bunch of revs on a 12 inch prop. That seemed to be corrected on the next run,but those first ones were a blast to run. Oh they held together well while doing it.
I've run the 20 & 28 extensively both glow and diesel and with a Fox 25 BB venturi and NVA they aren't bad runners. I've toyed with the idea of using a 45 on a shorter nosed model and have a cheap plaything to use. The Sportster line is quite frugal on fuel so you don't use much per flight. Oh and they aren't slag, I still have my first one and it still runs well. Bought in the early 80's and run for 10 years as a diesel, it still has the origional internals, will still start in a few flips.

One question though is there anyone that has a venturi that fits this thing and the draw bar holes are huge and most NVA will float  in them, Sleeving is allright but I'd probably want to put the nv through the venturi.
Thanks.
dennis