2 Stroke options 40 hp+

I'm considering the options for the affordaplane engine. I am not adverse to this ending up being registered experimental when I'm all done with it, so while I'd like it to meet Part 103, I'm not looking to get into the "you cant make weight with that engine an that plane" type discussion here. I was hoping to focus mostly on the engines here. Here were some engines I am considering. I was hoping for as light of weight as possible, high reliability and 40 hp or more. I'd really like to hear from anybody with first or second hand (Not via youtube) experience with any of these.

https://www.simoniniusa.com/?page=En...=Victor-1-Plus
The Simonini's look really good. But pricey! If any of you have experience with this, I'd appreciate hearing about them. I like that they claim 48 hp and only 70 lbs.

Thor 303 https://hughesultralights.com/shop.html The price is a good bit less than the previous engine. I talked to Mr. Hughes and he seemed to have a lot of information and was very positive about the engine.

Lastly, The plans were really designed around the Kawasaki 440. J-Bird has a whole catalogue of them which I got and have been looking at. It says they have both fan cooled and a water cooled option, but frankly, I'm a little concerned about reliability with these. On the positive side, I love Kawasaki motorcycles (shouldn't have ever sold my ZRX1100.) and this is by far the least expensive option and more power than a polini. However, I could always pull my motorcycle off the road if needed and these were not really made for airplanes originally. I'm going to call and speak to them and ask some questions soon I hope.

So, while I'd love to make an affordable affordaplane, I'm also not looking to master my engine out landing techniques by necessity. I'm willing to pay for reliability if there is one that is significantly better.

Are there any other options I should be considering? I've eliminated Hirth's, VW's and the like as being too heavy for this plane. They really want it to be around 70 lbs. But if I'm missing one, I'd love to hear about it.

Rotax is pretty much the gold standard for 2-stroke engines, and even though they're out of production, "like new" rebuilt engines are readily available. Either the 447 or 503 would likely do well in your application. The big single cylinder engines like the Victor are light and powerful, but they vibrate a lot. A half VW might work if you can live with 85 lbs.

Try Recpower.com. They sell Hirth engines which are still in production.

The F-23 is 50 hp. They say 78# with re-drive, full exhaust, and electric start, or 71# with re-drive, full exhaust, and pull start

The Hirths also have a 1,000 hr TBO (if operated at 75% or less...).

Thank you for the recommendations. I'll look into those too. I've got some time, I've figured out the parts with square tubing and am starting on the round tubing parts next. Then I have to figure out the fabric. Then I'll figure out the engine last. It's easier to just break it up like that I think.

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Update. I have looked at the F-23 a good bit and that does look like a really nice engine. I like the simplicity of air cooling so long as it doesnt cause failures. (My cessna is air cooled and it's fine). I wrote them to check on the pricing and would have to figure out the prop and drive ratio and all if I go this direction. Thanks for the link!

I spoke to Mr. J-Bird and he's recommending a 440 Kawasaki free air motor for my ultralight. The price is fair and it does sound like a great option.

I wrote recpower and got a quote on the F-23. New one's are going to be way out of my price range for this plane. They look awesome, but unless I could find a used/overhauled one, it's too much.