G'day

I'm with Donkey Doctor. I have gone away from two strokes to four strokes for most of my planes and I would definitely use a four stroke in a plane such as a Sportster. I would also use a Saito, either the 56 (I have two) or the 62 (I have one).

They cost more but they work better, last longer and are easier to live with. They also use a lot less fuel and are quieter. The down side is cost and complexity but this makes them more fun to own.

Of the others I would go for the OS. OS know about quality control. GMS is still learning. I am yet to see a GMS perform consistently. Yes, they are powerful (when they run) but they are rarely consistent throughout the rev range. GMS have yet to build a really good carby consistently. Some are OK, but many are not.

The OS LA 46 is not a particularly powerful engine but used properly will easily outlast the others and will fly a light Sportster well. It also has the added advantage of simplicity. No ball bearings to rust and a simple air bleed carby. They survive crashes better too.

If you really want a two stroke 46, I would consider the Thunder Tiger 46 Pro. They are made in Taiwan and are made to a much higher quality than GMS. They are also available from Tower for about $15 more. But if you want the best readily available 46, then I would buy an OS 46 AX. They are quite a bit more expensive than the others but a good deal better made than all but the Thunder Tiger which is a close second.

Price alone - GMS/Tower
Price/Quality compromise - Thunder Tiger
Quality alone - OS
Satisfaction - Saito