I have converted several engines over the last like 4 years (ok, so only a handfull got finished) and know the Mac 28/32's are about 4.5lb, homies are around the same (assuming still on magneto), and I've stripped down a few featherlite engines, had a 18cc down to 2lb with prop for gas/glow but didn't realize that those things come in right at 3lb on magneto, that's pretty good considering.

I know everyone knows that the featherlites are low on power, but I'm sure that has something to do with the 115-120* exhaust timing, getting the timing up to 145-150 requires nearly doubling the port height, they start out about 5/32" high... I have two of the 21cc engines ready to go and will run them this weekend so I can sell them and see what kind of power they put out. I use the mufflers held on by springs, the older style aren't crimped together or anything and you can just remove the baffles, if the plane allows you don't have to make any fancy outlet, you are left with about a 1/2" outlet (I imagine about right for the 18cc), even the mufflers I added the 1/2" tube to that's like 3" long are only 3oz. I'll try to get some pictures up this weekend, I think they make fairly clean conversions.

Id be interested in seeing what results you get. I have a pair of FL 21s Id like to put on a sport twin. I haven't fully converted mine, so I don't know what to expect yet. The one thing. I did notice is the intake manifold is a small diamiter only about 10mm.

I believe the manifold is the same between the 18 to 25 engines, if you look at it with the carb off you'll notice there isn't much room to enlarge it.

I attempted to run the engines I have ready to go on sunday, but then my starter battery died (only got it to fire once hand flipping, my arm is still sore from trying too hard) and the weather turned, it's been too cold and dark when I have had time to try agian this week, I have friday off to go to a RC swap meet (where I'm taking the engines) so I'll probably run them friday afternoon.

I think these things turn out pretty clean when converted, I'll get pics up of my conversions here in the next couple days, I took some just need to get them off of the camera.

Here are a few pics on my .60 size Big Stick with a Poulan 25cc. Easy fit, and is going to balance pretty easily. I moved the tail servos aft, the tank is moved to the CG. Looks like 5oz lead in the tail will handle it. Converted weight of the engine is 3lbs 3oz. There are 2 similar sticks at my club flying Zenoah 20ccs. The difference between the Poulan and the Zenoah is only 3 oz factoring the ignition and a 2500ma battery for the ignition. The wing loading goes from 15oz to around 20. Not bad. The plane weighs around 8.5 lbs. The plane had been flying an OS 120AX, probably the fastest climbing plane at the club! Got real tired of cleaning oil off red though.

What 60 size Stik is it. Also what are the planes dimensions. I have too many engines, but none are flying yet, I need a plane and I just can't seem to make enough time to build .

Its a Great Planes Big Stick. 66" wing span. These planes are pretty tolerant to experimentation, and are stoutly built. Has 1000 sq in of wing area, so can handle some extra weight.

there's also an "ultra easy stick" on ebay for pretty cheap, the 60 size is pretty similar to the great planes version, I got the 40 size just for curiosity's sake... I wanted to be different

I just pulled apart my first of the two bolt backplate engines and definetely like the 4 bolt engines better... they convert cleaner... I haven't trimmed the engines down or anything just took them out of the housing.

and to answer a question I've heard before, the jug won't bolt onto the 4 bolt backplate engines, the bolt spacing is different by a few thousandths, I might try modifying the jug on one I have that's kinda screwed if I can free it up, I don't know if the connecting rod bearings are the same size

It been a while since I have converted a 4 bolt, but I dont remember it being that different in what has to be trimmed off. I definately prefer the bolt on muffler. The muffler that is on my conversion is off the blower. Very small and compact. Weighs 3.5 oz as compared to nearly 6 oz for the trimmer. It is also catalyzed. At a 40:1 ratio I have never seen any smoke. I opend it up with 2) 3/8 holes and it seems to breathe fairly well. Plus I am doing my part to be green . Notice the deflector is facing into the "centrifugal oil slinger" (prop). Hoping it flys/runs well like this as it makes it quieter, if not I will just let it side dump. Noise is increasingly becoming an issue at our club.

Here's some pics of the 21's I was working on, i still have 2 of them, need to start them up still, had one going for a little bit, but my starter battery died and the weather didn't hold up, need to try again soon as I could really use the cash to get my commuter car going...

Looking good...

Good luck in selling them, I should think they will sell without any problems. How much do you get for them? Do you sell them here in the forum?

AV8TOR

I've sold a few on here, didn't have much issue at $75 which sounded reasonable...

Man, that is a give away price! You certainly are not making anything for your labor....

AV8TOR

yeah, at 3-4 hours labor minimum each to make it actually look decent, $5 each for the engine, ~$10 in materials (prop hub, washer, bolt, muffler tube), if I didn't like doing it it wouldn't be worth it