Wanted to revive this thread as I am back to tinkering with this engine. I have a cmp 90-120 size cessna on its way and am hoping to use my 25cc wacker for the plane. Since my last dealings I have gotten a nice aluminum pitts muffler and a 15mm walbro carb. I have gutted the intake to match the carb with a smooth runner. My engine is the version that has 4 bolts in the rear housing and 4 transfer ports and single ring. I have also dremeled in the intake and exhaust ports slightly to open them up on the sides another 1-2mm (which produced an additional 300rpm gain on the 16x8). I checked my compression and I get 120psi of compression which seems nice and high compared to others. Running 40:1 mix with 93 octane I get the following:

16x8 MA 7300 rpm
17x6 APC 7800 rpm
17x6 APC 7650 rpm with one pipe plugged on the pitts (which cuts down noise by 50% !!)

I have seen others stating that they get 8k on the 16x8 MA. Not sure how, my engine probably has about a gallon through it and it can't make it there. However, the 17x6 readings look promising and much better than my previous tach of 6400 on the 16x8 with the stock carb and exhaust. What do you guys think? Will she fly the cessna in the constant 10mph winds here in illinois? On that tigermoth it was a dissapoinment as it put out about the same as the 91 fourstoke powerwise but it has pepped up quite a bit and I expect the cessna to come out around 13-14 lbs. Not looking for 3d just the occasional loop and could live with it if I have to dive briefly. Any other ideas to bring up power?

It has been so long since I used my 25cc leafblower motor that I do not remember what it got for RPM. I have moved on to the Homelite 33cc chainsaw motors, huge power increase and I can still pick them up at yard sales for around 40.00.

I also now go for the chainsaw conversions - way more power with no modifications necessary. Even can use the original carbs.

Yeah, but I don't want to do another conversion. I remember it taking hours to grind off all the extra metal on this motor and grind the flywheel and balance it and then try to find someone who makes the prop adapter and lighter muffler, ect. It was a fun experience but I am at the GO or NO GO point. So either this engine does the trick and I get some use out of it or I open up the wallet and get a zenoah or evolution gasser. I would like to find a 2 ring piston for it to give it a try. It will hand start when warm after about 5 flips. Almost imposible to start it by hand when cold though. My electric starter starts it just fine.

Didn't mean to imply that you should give up that motor Just that I havent been into the featherlites in some time, and why. I love my little featherlite, just need a good airframe to put it in. The Eindecker was perfect but I destroyed that one and put a four stroke glow on the new one to fly it off floats.

Do you remember what your Eindecker weighed? Was it able to loop ok?

It looped, rolled, wingovers, etc etc. It was a great performer. No unlimited verticels though.
I dont remember what its weight was though.

i put mine in my sons Balsa USA D-VIII(Pic of engine is on the first page of this thread.)weighed 14 lbs.RTF.has a 84inch ws.flew it ok but it was underpowered and i wasnt comfortable with it.meaning there just wasnt enough reserve power for emergencys or windy conditions in my opion.ive since put a homy 30cc 2 ring on it and flys it at half throttle.it now weighs 14.5 lbs if i remember right but since i added a little heavier engine i was able to use a smaller battery pack and move it back from the nose to balance better.if you do try and run the poulan dont make it real nose heavy and be ready just in case its underpowered.maybe yours performs better than mine did also.hope this helps.

Buck, does your DVIII (your sons) have a tendancy to tipstall and spin?

Did you make any timing/porting modifications on your engine Buck?
If not I think you can get more power if you change the exhaust and intake timing, featherlights and poulan tend to be low on these two items.
I did it on mine and I'm getting 8300 rpms on a 16x6 apc prop and flew a 120 size ultimate bipe by Nitroplanes, it flew GREAT until I did a BOOBOO while a low inverted pass carb lost a needle and killed the engine (brain said pull up) and you've already know the rest of the story[&o]

Prop Nut:I havent had any problems with tip stalling or spins.the only thing i did was use a single push rod for the elevator so when we loop it it has a tendacy to roll out because the elevator is so big its twisting more on the side that doesnt have the horn on it.were going to run 2 control rods to cure this.My son and i havent really had the plane slow enough to stall i guess.I land with the throttle,blip it up and down to control airspeed and decent and only use elevator at last minute to flair.
Aero Nut:no i didnt do any mods to the engine.It was the first one i did a ways back before i really started to get into these engines and reading this forum.Then after a few flights the spring on the muffler broke twice so i sold it.a student of mine put it on a Lazy Ace 60-90 size(74-? ws).I havent maidened it yet.