what engine would a 25cc homelite engine or other 25cc weedeater/leaf blower engine of the same cc what would it compare to in glow engine power.. more power than say a saito 1.80 right? what would be a good size plane to mate a 25 or 30cc weedeater engine to as far as a spad goes.. 70-80" wingspan spad? will it be too much power? also should i go glow ignition with a fuel/gas mix instead of magneto powered spark plug? or should i stick with the magneto and spark plug and just counter for the weight? any suggestions would be greatly appreciated! thanks!

The homelite will never match the power of a Saito 180 and of course will weigh more. about any 90 to 120 size plane should match up with the homey. they are a nice little engine. I tend to like gas/glow better than mag and will save on weight. If you stay with the mag mount the engine as far back as you can for balance.

That's for a stock, or very mildly modified Homelite 25cc. My hopped up Homelite 25cc engines turn an APC 16 x 8 prop at an honest 8700 plus, which is about what I often see claimed for the Saito 180. Hopping them is best left for those familiar with modifying engines however....

AV8TOR

thanks troy! but wow, a .90? really? i guess i will run magneto and spark plug for a while because i spend an unreasonable amount of money on glow fuel and running gas will be much cheaper even at 3+ $ per gallon! so maybe somewhere around 70" wingspan for the weedeater engine?

For a stock Homelite 25cc I recommend around 1000 square inches of wing area, and a ready to fly weight of no more than about 12 lbs. if you want some aerobatic potential. Lighter is of course, better.

AV8TOR

if i keep the engine magneto and spark plug ignition what size prop should i get? also master airscrew or apc?

Av8tor is right on with the 1000 sq" and 12 pound recomendations. If you are new to conversion engines leaving the mag and sparkplug on is a reasonable thing to do although hand starting may be difficult The Homey is a great little engine and once started will never fail. Av8tor what would you think about a Citabra powered up with a Homey?

My Echo 23.6cc weighs 34 ounces with the muffler and radial mount. A Saito 1.80 weighs 31 ounces with no muffler or mount. My CH ignition with Bosch cap and battery weighs about 7 ounces. Total flying weight is 40 ounces on my Echo and the Saito will be right there with a good mount and muffler. Run it on a mag and the Echo will weigh more, run it on gas/glow and it will weigh less than the Saito. Biggest advantage here is gas is still way cheaper than glow and will fly much longer on the same fuel load. The Echo will turn a 16/8 about 7500 here in the humidity and heat. Ahhh choices...

Tim

Wow, I didn't realize the Saito weighed quite that much... Makes the gassers look even better!

I did a Homelite 25cc for a friend. He couldn't afford the electronic ignition and didn't want to go Gas/Glow so we left the magneto on it and just took the fins off the flywheel and rebalanced it. Virtually the only porting I did was to take out the bridge in the exhaust port. I gutted the stock muffler and put two 1/2" i.d. outlets in it, and installed a 10mm venturi carb. I think I left the base gasket out to raise the compression a bit too, and we added a Frank Bowman ring for use with a pinned piston. It turns an APC 15 x 8 prop at 9400 rpms, or an APC 16 x 8 at 8700. Pretty good performance for an engine with the stock ignition and no port timing changes...

I think one would do fine with a Citabria, or really any plane with the specs of around 1000 square inches and 12 lbs. or less.

AV8TOR

I give a vote for a CG Wild Stick. It's not the best model out there... but it's the best "Bang for your $$$." And... it will fly well on a 25cc. I have one with a stock Toro 25cc spinning a 18x6-10 Zinger. The all up weight is just at 12 Lbs.

Here's a link to Tower's site.

http://www3.towerhobbies.com/cgi-bin...?&I=LXJUV0&P=0


If you give it a week or so... Tower always runs sales where if you spend so much... you get a discount. Normally at x-mass time, you could save $20 to $25 on a $150-$200 purchase. And if you are a member... you get free shipping.

Just my two cents.

Here's mine:

The Ultra Stik Lite 120 from Hangar 9 is also a good flyer and does well with something like a Homelite 25cc. There are many choices out there...

Something aerobatic but less "Stik like" would be the largest "Twist" from Hangar 9 as well.

AV8TOR

Have 3 Homy. engines. two have a bar across the exhaust port. The other is a little larger with ouit the bar. I believe the lager one is 33cc. What can the other engines be, 24, 26 maybe? Is there a better way to find out the cc's with taking the engines apart and measuring the bore?

The ones with the bridge in the exhaust port are probably the standard 25cc models. If the other one without the port is the same physical size externally, it is a 30cc. If it looks different and is larger externally, it might be the 33cc. Either one is a good engine. Actually they all are, it's just that the 30cc has more power with the same weight.

If you can measure them, the formula for displacement is: (bore x bore) x stroke x .7854. If you measure in inches, this will give you cubic inches. You then divide by .061 to get cc.

AV8TOR

Thanks AV8TOR The info. you sent is great, just what I needed. Also the hop-up info is good. I think I'm going to try that with one of the engines. Think if I wanted to change the timing I'l have to bridge the coil mount to be able to that. What do you think?

I don't really understand the comparison between the Saito 1.80 and a 25cc gas engine. I have a Skyshark Eagle w/ a Saito 1.80 and it flies it with authority. A 25cc gas would not get it in the air. I bought the palne from a fellow flyer who had a strong running 33cc conversion on the plane and it was scary watching it struggle to stay in the air. He did not want to go through the expense of buying the right engine for the plane so he sold it to me. Most manufacturers recommend a 1.80 or 50cc. I have never seen a recommendation for a 1.80 or a 25cc.

You can also change the ignition timing by just leaving the key out and moving the flywheel. Much easier that way. The key is only there to reference the flywheel to the factory desired timing; it doesn't literally hold the flywheel in position. You can leave the key out and just to be sure, use a smear of loctite on the flywheel taper. It won't move.

AV8TOR

flaminheli -- It really depends on the 25cc gasser, and how powerful it is. My Homelite 30cc will perform with a Saito 1.80 but it has been hopped up.

Another thing is that often times people don't think about pitch speed. The gassers usually don't turn the rpms that a glow engine does, and often need a higher pitch prop to perform the same in an airplane as a similar power glow engine. It can make an airplane extremely "doggy" if it is improperly propped according to the desired flight speed versus the characteristics of the engine.

Example:

Saito at 9500 with an 8" pitch = Approximately 72 mph

25cc gasser at 7500 with an 8" pitch = Approximately 56 mph

AV8TOR