Engine information
 

Anyone know what engine this is and what are your thoughts on the condition? I believe it to be a 30cc Homelite. The rings are pinned so I will get a bowman ring. Do I need to get two rings or just the top ring? Also the top if the piston has a nick on it. Will this affect operation and is their a way of sanding it? A bit of carbon on the top of the piston as well.

Thanks

All in all probably a useable engine, but it's worn. I don't believe it is "virgin". The sideways sanding/score marks in the cylinder were made by someone with too coarse a grit sandpaper. The base gasket does not appear stock, and it is covering portions of the transfer port passages, and the transfer ports appear to be the small ones. The piston is worn. Normally I use a Bowman ring in the top groove only, and a stock ring in the second groove. It appears to me that a piece of the second ring is broken off right where it is supposed to fit over the pin in the piston on this one. If the top ring is undamaged, just use it in the second groove.

The engine can be rebuilt and will run, but it is not the best candidate for an engine you are going to put a lot of time into souping up due to the wear on the piston and condition of the cylinder. It is a 30cc. The fastest, easiest way to tell a 25cc from a 30cc Homelite it to just look into the exhaust port. The 25cc has the bridge in the exhaust port while the 30cc does not.

So I have a 11mm carb, Would this engine be a good for this carb? What can I do to get this engine a good runner?

I would clean everything up real well. Take some 400 grit sandpaper used with solvent and lightly sand the cylinder bore. Then put the top ring in the second groove, a Frank Bowman ring in the top groove, install a new base gasket and you should be good to go. An 11mm carb will work fine.

It is not worn enough that it won't make a good running, use-able engine. I would just choose one in slightly better condition to use as a base for an extensive hop up project.

AV8TOR

Sand the bore up and down like the piston would travel? What solvent? Anything with the piston?

Lightly clean the piston with some Scotchbrite and soap and water. Sand the bore in a circular motion opposite to the way the piston moves. Use any solvent, such as mineral spirits, kerosene, diesel fuel, (stinky), even some WD-40 would be better than nothing. Some oven cleaner will help with the carbon in the head, but don't let it soak too long.

AV8TOR

Thanks. Their is a nick in the top of the piston with a piece of the piston sticking up slightly. Can this be repaired or is the piston junk? Sanded flush?

Carefully cut the raised metal off with a sharp knife, then gently file or sand the area smooth. It shouldn't hurt a thing from what I can see of the pictures. I sometimes grind the piston in certain engines half way down to the ring groove in the area of the exhaust port. There's material to work with on the piston top.

AV8TOR

I looked at the back plate and not much room for stuffing the crankcase. Any other ways of increasing compression? Leaving off the jug/block gasket to achieve .020

Clean the cylinder base and crankcase very well. Then bolt the cylinder on without a gasket. If the piston to head clearance then measures .020" or close to it, then just final assemble the engine with some Yamabond or other case sealing product and leave the gasket out.

AV8TOR

Thanks, What are your thoughts on the intake and exhaust timing for this engine?

Pick up a glaze breaker at your local auto parts store and run that thru the cylinder just enough to say it looks good. Kerosene would do for a lube while using the glaze breaker. Keeps the stones from loading up and allows for a clean job. Be sure to rinse completely after this work.

why not just buy a new engine

Depending on the bore diameter, a brake cylinder hone may be better sized.

Regards, Richard

Junk... Pitch the top end. Look at. the wear patterns. The piston skirt is well worn and it has caused some wear in the jug. Most two strokes that die for causes other than melting down die because the piston wears, it starts rocking in the bore, then breaks the skirt off then boom.... Hint is all of those machining grooves you can see in the piston near the rod.... Guess what on a new piston you will see those run all the way around all nice and even... They actually help hold the oil film for lubrication and reduce drag. Notice how near the ring they are all still there but as you move down the piston, they dissapear. You can see the wear the rocking has caused in the jug.. you would probably need to go well over .030 on a bore to get it round... Dont waste money on a new ring, it will just get you to the end sooner. Find another in better condition for your final product and use this one to learn on...

So this engine is not worth the time or effort to get to run? Can anyone help with part's for this engine?

Buy that Kawasaki 50cc I offered you. It doesn't weigh much more, and will put out so much more thrust it will scare you, and no modifications needed.... Just bolt it on and run it. You'd probably be the king of the airboat scene there.

AV8TOR

I need to stay in the 25 to 30 cc range for the hull I built. I would really like to get this engine going to put on the hull. After all, I did purchase this engine here on rcu from a well know engine builder. Any help would be appreciated.

I'd be going back to the seller asking for a refund or something and using a different powerplant. Given the wear shown on the piston, I'd tend to agree with not doing a lot of work to this engine. It'll run I'm sure, but if the piston and cylinder are worn, ring sealing will suffer even if using new rings.

I have a Homelite 30cc engine laying around myself but I'm unsure of its condition internally. It appears to be low runtime and came off a weed trimmer. Has a Zama carb on it.

Interested in selling the engine?

Could I use a piston from another engine? If so What type of engine and how do I measure if needed?

I get the idea these Homelite engines are not made very well. My low time engine looks pretty worn. Here's some pictures of the piston.

That looks just about the shape mine is in. What are you planning for this engine?

I was going to originally strip it down and convert it to glow plug ignition and glow fuel and put it on something. Thought about modifying the clutch and putting it on a bicycle. I have no interest in putting it on a plane - don't care for anything that big.

Go take a look around on Daves for some good information & parts. Plus new short blocks.

http://www.davesmotors.com/Products/Complete-Engines/

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?