I'm new to large powered planes and have gotten a (mostly) framed-up 1/4 scale Sig J-3, along with an elderly Ryobi 31cc 'strimmer engine. Are there still conversion bits available for this engine? Is it worthwhile to use it once converted, or should I look elsewhere? I mostly fly slope (and electrics with my son)- with no interest in glow at all, but I sure do like big'uns.

Yes you can get conversion parts.

If you just want a cheap engine that runs well the Ryobi are a good choice, old Ryobis just run better. If you use the magneto you'll have to use a starter or a pull rope to start it, but they run fine. I can sell you the stuff to convert it to electronic ignition, it doesn't make more power than a magneto that has been modified for more advance timing, but it hand flips and idles better.

http://www.rcuniverse.com/forum/m_65...tm.htm#6574752

Thanks. This engine looks has slightly different bosses in the crankcase bolt-up areas than the ones in the conversion sites. The threaded part of the shaft has been cut off, the choke plate is missing, and it looks like it has cut a fair amount of grass.I don't mind fiddling with this (winter's almost here) but a plug and play zenoah or SPE would be OK too.

You can clean that up easily to make a good motor. If you want more power just take the magneto flywheel and with a dremal grind a keyway for the woddruff key that's about 1/8 inch counter-clock wise from the slot that's there, you'll gain 500 rpm.

The 26 SPEs from BMCA and Brillelli are good also, if you want a rear carb the LS-26 is a good choice.

What's an "LS-26"?

AV8TOR

Thank you- 'sounds like the cheapest mod of all. I assume these consumer engines are generally detuned to make them durable and easy to start. Regarding this mod, is this new keyway indexed counter-clockwise 1/8" while looking at the backside of the flywheel? Assuming this advances the timing a few degrees, how adversly will this affect: starting, low idle, or early part of transition?
I'm looking for easy starting, an idle that doesn't shake the glue joints loose, transition without dying, and with enough quiet power to fly a 1/4 sig cub realistically. I know, "good luck with that". So far I have nothing into this engine and would be happy to spend what it takes to get towards those goals. I hate throwing away perfectly good lumps of metal too.

Ls-26- 'looks good: [link]http://lsproengines.com/lspro_015.htm[/link]

The advanced timing would make it idle rougher. Ideally, you would switch to auto advance electronic ignition for more power, less weight, smooth idle, and the ability to hand start if desired.

For reference, my brother has a stock Ryobi on his Ryans Rebel. The plane has an 80" wingspan and weighs about 14.5 lbs. The Ryobi flies it nicely. Sufficient power for basic aerobatics, but not a rocket.

AV8TOR

Yes, might be a little harder to start. My friend has been doing this for years, he uses a pull rope to start them. When I had a mag on mine I used a regular starter. My friend liked to fainted when he saw me had flip my Ryobi after I converted it to EI, he bought two EIs from LS that day.

EI is the way to go.

Yes Av8tor, that Ryobi is stock!! if you play with the exhaust timing and bigger carb and open muffler you would have more power and even more if you took the ignition flywheel off and put EI or convert to Gas/Glow.

Actually, I mis-stated that. It should have read "stock Ryobi except for electronic ignition" because we did switch it over to electronic igntion as that's what my brother wanted.

The plane is here at my house right now, and it keeps calling to me saying "Hey, at least gut my muffler and give it a bigger outlet!" (Something about a stock engine just makes me crazy until I modify it, especially if/when I know there is more power to be easily had....)



AV8TOR

av8tor77: How do you like how the Ryobi runs, that your borother has with electronic ignition. I bet it fairly smooth and quite reliable? Capt,n

It runs well. It doesn't start as easily nor idle has slowly/smoothly as my Gas/Glow engines however.

AV8TOR

AV8TOR: If both engines had the exact same mods...which one has more RPM or power? Capt,n

When converting engines to Gas/Glow, I generally see about a 200 rpm increase in power, as well as a smoother, slower idle.

AV8TOR

What's involved in the conversion to gas/glow?

It's all here: http://www.rcuniverse.com/forum/m_12...page_74/tm.htm

AV8TOR

You can move the timming with out making a key way. You can take out the key and just move the flywheel 6 degres. Hold it in place real good and lock it down with the prop hub. it will hold. it is on a taper and will not move unless you hit the prop on somthing. like the ground. but with mine I had to hit the ground hard. the prop broke and the flywheel moved. but I hit the ground so hard it broke alot more then the prop. lol

It does work and works well. but going with cdi is beter then changing the timming on a mag.. but Gas/Glow is the best. and it is alot of fun.

Paul

Is the increase of 200 RPM just the engine breaking in or you using a already broke in engine with nothing else changed except spark plug to glow plug? Just curious. Capt,n

That's the gain I usually see on an already broken in engine.

AV8TOR

Do you think its the Nitro in glow fuel that is giving the boost in RPM? Not sure...but I think alcohol has less BTU,S (power) per ounce than gas. If you do same blend without Nito...what happens? Thanks,Capt,n[:-]

From what I can see on gas/glow is that a glow works like a Deasal do. Gas explodes in the slender and then hammers the piston down. The burst is only about 35% for the bore power line. (witch is the part of the slender from the head to the ports) the rest of the % is free run. Deasal and glow burns and pushes the piston down and there is about 90 to 95% of the power line. The fuel burns slower and pushes the piston not hammers. Witch will give the engine more tork. The engine is under a load at all time with a prop on it so the hire tork will give it more rpm under the load. I will try to find the page on how the power is from gas engines to glow that said this. It made more senses to me on that page. But with gas you can change the timing to do that same thing that you can not with glow.

But I do know this. I have a quadra 40, on gas it will tern a 18x10 prop nice. On gas/glow it will tern a 20x10 the same as the 18x10 on gas. and it will tern the 20x10 prop the same rpms as my 3w 42 does on gas. Right now I am trying to get a plug adapter that is 10mm so I can see what my w3 will do on gas/slow.

And gas/glow is just plane fun. The look on people faces when they here it is a gas/glow mix it cool. and it make gate talk at the fild.

Paul

Ps Some one tell me how to spell Deasal I know I am not doing it right.

Diesel and cylinder

Thanks works for me lol