AV8TOR, did you ever convert a 29cc engine like this to RC? Thanks, John

http://www.davesmotors.com/zenoah-g2...gine-core.html

Dave's only deals in Zenoah and Zenoah clones. Homelite parts have gotten hard to find. Usually it's not an issue because we can buy bearings and seals from Boca, and rings from Frank Bowman. Pistons and cylinders, if in good shape to begin with are rarely a problem, because you can't fly enough to ever wear one out in your lifetime.

AV8TOR

Thanks for the link.

No, not that one, but I did something similar. That is my super secret "killer engine" I told you about some time ago. I used a Zenoah G-23 along with one of Dave's Chung Yang big bore kits. I made major modifications to the crankcase. It came out at under 2.5 lbs ready to fly, and turned an APC 16 x 8 prop at 10,200 rpms, WITHOUT a tuned pipe. One of the best engines I ever built!! I've got the pieces rounded up to do another. Not for sale, only for my use, though I could custom build one for someone if they wanted.

AV8TOR

Hi, I have an older G-23 with CDI and I love it. However, more power would be nice also. Would you tell us what modification to ther case are necessary? My case is already trimmed for minimum weight. Thank you very much.

Sincerely, Richard

The modifications I did to the crankcase were not for power; just to reduce the weight. I never understood why Zenoah left those four ugly threaded bosses on the front of the engine when used as an airplane engine. So, I turned the crankshaft and crankcase around, cut the tail of the crankshaft off so it wouldn't protrude from the case, made a block off plug for that opening, and used the four threaded bosses as my mounting point for engine stand offs. The engine looks much more compact, and is lighter. I suppose I gained just a touch of power by eliminating the seal drag of one of the crankshaft seals, but it wouldn't be much...

The pics kind of tell the story if you study them.

AV8TOR

AV8TOR, Do you think the stock older Zenoah 23cc engines that use 4 bolts to hold the jug in place, bolt on the 29cc Chung Yang cylinder? Would it be easy to attach to the 29cc to the "older" 23cc engine? Thanks, Capt,n Just curious.......

Yes, you can hop up the older G-23. Dave's has big bore hop up kits for either the 2 or 4 bolt Zenoahs. If I remember right though, you can only get to 26 or 27cc unless you change the crank. But I didn't change the crank on mine, just added the big bore cylinder. But the 2 bolt cylinders are the older ones, and the 4 bolt ones are the newer style in my understanding. Keep in mind that the Zenoah tends to be a high rpm engine anyway, and the hop up cylinder makes it more so due to the port timing. The exhaust is around 172 degrees I believe I measured. It probably won't like anything larger than a 16 x 8 prop, and it will need premium gasoline due to the higher compression ratio, but it will scream!! I used a 12.7 mm carb on mine, and a nice free beathing muffler. It makes a very nice running, responsive and powerful engine.

I also recommend running 20:1 oil in one of these due to the high power and rpms involved.

AV8TOR

Got a question for the OP. Why are you contemplating using this engine? The cost of a bowman ring and the labor required to get this engine "up to speed" is excessive compared to just buying a good used reliable engine i.e. Zenoah, DLE etc.

Glenn

I have to step in on that one myself. The answer is the very reasons we all do conversion engines. One is cost. A conversion engine, even if it needs rebuilt, will cost a small fraction of the cost of even a Chinese purpose built engine. (Many people get the engines themselves either for free or a token fee. So the only cost is the conversion or rebuild parts.) I myself often sell complete, ready to fly converted engines for around a hundred bucks or so. You won't find a purpose built engine for that price.

Another is "just for the fun of it". It is very rewarding to take an engine and re-purpose it for your airplane. Then there is also the "wow" factor when you tell people that the engine on the airplane they just saw fly, came off of a (weedeater, leaf blower, chainsaw, etc.). This is quite fun and rewarding as well.

Lastly, is quality. The Stihl, Echo, Homelite, etc. engines we all tend to use are of considerably higher quality than any of the Chinese engines, and will be more durable, especially at high rpms. I should add that a properly hopped up conversion engine will also be more powerful than the Chinese engines, as evidenced by the performance of the engine I posted about above.

AV8TOR

I agree with av8tor. These engines are built for work, commercial use etc.

Just like AV8TOR says, the conversion engine are better quality than most china built engines. Capt,n

Can I take a crank from a 30cc Homelite and install it in a 25cc engine Homelite?

Won't do you any good. The stroke is the same. It is the bore that is different between the 25 and 30cc engines. I have the solution to your problem right here....

Details?

Stock exhaust timing on a 26cc is 164 degrees.
The four port cylinders won't fit the old G-23 two port crankcase as the transfer bowls won't line up correctly with the transfer ports. there is not enough meat on the case to grind it out to fit.
They run just fine on 89, CR is not that high.
props and rpm are 18 x 6 ~ 10, 16 x 8 ~ 12
7,000~8,500 rpm

We are speaking of the Chung Yang hop up cylinders made for the Zenoah 23 and 26cc engines. They are availabe in both two and four bolt versions, have the exhaust timing specs I mentioned, and are recommended to be run with premium fuel.

My Zenoah with the Chung Yang hop up cylinder turns an APC 16 X 8 prop at 10,200 rpms without a tuned pipe.

AV8TOR

I sent you a PM.

AV8TOR

I was wondering about the details also?

It's just a Homelite 30cc in very nice condition that I have for sale. $50 plus shipping. (Not converted.)

AV8TOR