I run mine real fat. So you can feel it coming out of the muffler. I've got 5 flights on my TOC 53 and I've been through a gallon. I'm getting ready to lean it out after about another half gallon.

Originally Posted by bodywerks

gone are the days of converted chainsaw engines for giant scale aerobatics, though. today's cylinders are purpose-built for our application, and it should stand to reason that they will break in differently than a chainsaw...not saying that your way is wrong, but there is more than one way to do something right in this case.

I KNOW you've seen a Brison, Zenoah, Brillelli, Taurus engine.

ALL chainsaw/industrial cylinders, carbs, pistons and rods that have been strapped to a machined case and altered crankshaft.

A 2-stroke gas engine, is a 2-stroke gas engine, is a 2-stroke gas engine. They all break in the same. The ONLY reason why the manufacturers recommendations are so conservative, with regard to break in, is to protect their own butts.

Originally Posted by bodywerks

gone are the days of converted chainsaw engines for giant scale aerobatics, though. today's cylinders are purpose-built for our application, and it should stand to reason that they will break in differently than a chainsaw...not saying that your way is wrong, but there is more than one way to do something right in this case.

Converted chain saw engines are very much still with us. Case in point, the Kroma 180s use Sthil cylinders, if this is not a conversion, then I dont know what is. The industrial market for this type powerplant is huge compared to what we use them for. We are just lucky to be able to use these finely designed items for our hobby. Cant imagine what the cost would be for model engine manufactures to have the cylinders cast to their specs.

Yes they do cost a lot from what I have been told.

You are correct. Many of the engine available have chansaw roots. Some like DA, 3W, or ZDZ have thier own cylinders cast. I don't feel one is better than the other. Take a cylinder made for a very expensive Sthil, Husqavarna, Red Max, Sachs, or Echo chansaw, and you have a cylinder that was made to take abuse and hold up to it. Far more demanding than the eay life we give them. Proper oil, cooling, and for the most part proper tuning. Not to mention a constant load of a prop, not the jarring load of cutting wood. These companies spent a ton of money developing thier engines to hold up under the worst conditions. More money than DA or ZDZ have to play with to develop thier engines.

The point is, tune your engine from day one. Do not let it run rich or lean. Both are no good for it. If it is burbleing an spitting raw fuel, you are slowley killing it. Carbon buildup in a gas engine will kill it just like running too lean will.

I don't consider Stihl, Brison, Sachs, etc. an aerobatic competition engine. I didn't say converted engines didn't exist, just that they may not totally meet some of our performance demands. Purpose-built cylinders might have an entirely different porting design to optimize the mid-range and overall performance. Pistons might also be lighter or modified to help achieve a lightweight engine, etc., etc., etc...
The difference between a household use chainsaw/weedeater and our engines' application is that Joe Chainsaw just wants an engine that runs at WOT whilst hacking away at that branch, and he will likely never know the difference between gaining or losing 300 or so RPM by practicing a specific break-in technique. Also, I think the load of a chain trying to saw through a piece of wet eucalyptus pouts a different kind of strain on the engine than a prop does cutting through air. Yes, there are similarities, but also several differences...

Well, there's plenty of guys using those engines in IMAC. Aerobatic competition doesn't get any stiffer than that.

Originally Posted by bodywerks

I don't consider Stihl, Brison, Sachs, etc. an aerobatic competition engine. I didn't say converted engines didn't exist, just that they may not totally meet some of our performance demands. Purpose-built cylinders might have an entirely different porting design to optimize the mid-range and overall performance. Pistons might also be lighter or modified to help achieve a lightweight engine, etc., etc., etc...
The difference between a household use chainsaw/weedeater and our engines' application is that Joe Chainsaw just wants an engine that runs at WOT whilst hacking away at that branch, and he will likely never know the difference between gaining or losing 300 or so RPM by practicing a specific break-in technique. Also, I think the load of a chain trying to saw through a piece of wet eucalyptus pouts a different kind of strain on the engine than a prop does cutting through air. Yes, there are similarities, but also several differences...

From what ive been told by IMAC flyers, the massaged engines, Ie, port changes, smoothed ports, enlarged exhaust ports, etc do not have the power of a stock engine. And I have built several large twins, and found out the hard way, One cannot mess with the porting on these industrial engines, and improve the performance, espically the exhaust port, enlarging it will reduce performance. Years ago Homelite found that by reducing the size of the exhaust port, power would increase. They called it "capture porting". At one time I was building a 6 c.i. Homelitefor a customer, was about 1983, and had the stock cylinder, and Homelite sent me the new one with an exhaust port about 1/2 the size of the stock one, tached the stock one, then installed the new one, 1000 more rpm. Fellows I feel that if assemblers use chain saw cylinders, or have them made to their specs, there will be hardly any difference in performance. Notice I said assemblers, not manufactures, because there are NO 100% manufactures of our engines. And to be redundent, there is No break in procedure for a chain saw/weedeater/leaf blower, in their instructions. I have also seen the results of running 32-1 oil when new, all this is going to do is carbon the combustion areas so badly that disasambly will be the only way to get the power up to where its supposed to be. Been there, more than 20 times, in the past 27 years of working on these engines for fellow modelers. Believe what you want, its your right, am just trying to pass along what Ive learned over the years.
Regards to everyone
Jack

Never had all that much carbon build up when using Penzoil 32-40:1..If the needles are set right and proper cooling is giving.


Neither has this other guy
http://www.geistware.com/rcmodeling/...test/index.htm

One more thing to ponder,,,,,more oil = more power

http://www.bridgestonemotorcycle.com...oilpremix6.pdf

You're wasting your time....Elson and Pat put more time on engines than almost anyone else, they have been bucking "conventional wisdom" for years..I have seen the insides of Elson's 3ws and a few of Pat's...They know what he's talking about....Most RC flyers won't run their engines long enough to see those results, so "conventional wisdom" rules....
The cylinder head temp on the air cooled Suzuki during the dyno tests was a lot higher than "conventional wisdom" says will damage an engine...Approaching 400F....Interesting ?????
What do those guys know, they're just motorcycle guys...How can anything like that apply to purpose built lightly loaded model airplane engines---We ALL know model airplane engines are better than converted chainsaw engines..Isn't that what the manufacturers tell us ?

Originally Posted by RTK

Never had all that much carbon build up when using Penzoil 32-40:1..If the needles are set right and proper cooling is giving.


Neither has this other guy
http://www.geistware.com/rcmodeling/...test/index.htm

One more thing to ponder,,,,,more oil = more power

http://www.bridgestonemotorcycle.com...oilpremix6.pdf

Geistware indeed. Why dont you ask this guy what his experence is with giants. Also My friend was here with his new 150 cc engine the other day, and was using the grass oil,at 32-1, 32-10 mez, turned 5500 rpm, changed to 50-1 let run a couple minutes, turned 5700 rpm, now where on earth did anyone get the misinformed idea that "more oil, more power?" I just dont understand you 32-1 fellows. Now if you are running a steel cylinder, cast rings, 16-1 may be correct. But guys, we are not running engines like this. Why can't this argument come to a quiet close, and everyone do what ever they want to do?

Don't know that there is any argument going on... Fairly peaceful thread if you ask me... Well, compared to other threads anyway...

This is exactly the reason I started this thread... To get quantitative & qualitative responses to a question that no one has really answered... Yes, we have manufacturer recommendations, but as we all know, they fall short when it comes to the real-world...

I really hope this thread can continue without the "Pros" telling everyone else that they're stoopid and don't know WTF they are doing... Share the wisdom guys, not the 'tude...

Great stuff guys...

Originally Posted by jack strickland

Geistware indeed. Why dont you ask this guy what his experence is with giants. Also My friend was here with his new 150 cc engine the other day, and was using the grass oil,at 32-1, 32-10 mez, turned 5500 rpm, changed to 50-1 let run a couple minutes, turned 5700 rpm, now where on earth did anyone get the misinformed idea that "more oil, more power?" I just dont understand you 32-1 fellows. Now if you are running a steel cylinder, cast rings, 16-1 may be correct. But guys, we are not running engines like this. Why can't this argument come to a quiet close, and everyone do what ever they want to do?

Geistware did not do that report Jack, he borrowed it to reprint. Did you even read any of the test data that I posted the links to???
The guy (Elson) who did the testing on puts more hours running an engine in one summer than most do in a life time. He also pushes them pretty hard at times.

As for the more oil = more power,,, apparently you did not read the second article either.
If your friend picked up rpm's after changing the oil, then he didn't have the needles set correctly in the first place.
The tests show what has been stated by myself and many others, no more no less.

If it comes to a quiet close with bogus information that is wrong.

Originally Posted by Torqued-Up

I really hope this thread can continue without the "Pros" telling everyone else that they're stoopid and don't know WTF they are doing... Share the wisdom guys, not the 'tude...

Great stuff guys...

This is why I posted "tests" that were run as scientifically as possible. It is tough to argue with them. Some still continue too though and base there reasoning on, I had a friend...............Unfortunately I have a lot of friends can't tune there way out of a wet paper bag.
Don't really think anybody has had the bad "tude" that I have read.

I tend to believe RTK, RCIGN and Pat Roy more than most of the self proclaimed "expurts" on ANY forum. Pat puts in a LOT of hours on 2-strokes. Maybe not as many hours as Elson, but a helluva lot more than your average modeler. RCIGN has been around gas 2-strokes longer than a lot of modelers have been alive. He's THE guru when it comes to modifications and general knowledge. RTK always give sensible advice without an attitude, and I am fairly certain he hangs out with Pat--so they share similar experiences and knowledge.

I have not bought into the "synthetic is better" quite yet. But, thats only because I've been using one particular brand of oil for about 6yrs now and have not noticed even a HINT of unusual carbon development or gummed up engines. It's 50% dinosaur and 50% synthetic. I am convinced the reason why I see no carbon build-up is because I actually know how to tune and baffle an engine. Never cooked one. I recently finished breaking in an engine, so I took the muffler off after 8 gallons. Was running it at 32:1. It had ONE tiny smudge of soft carbon on top of the piston--near the exhaust port. I wiped it off with my finger by simply sticking my finger in the exhaust port and wiping it softly. Gone. No more carbon at all. Slight tanning on the side of the piston between the first and second rings. No tanning or browning below the second ring. Just a shiny piston with machine/tool marks still on the skirt--just like it was from the factory. Took the plug out and then stuck a small mirror inside the exhaust port. Should have taken pictures. Brown, but no carbon.

I've leaned that engine to 40:1 and will fly it another 10-15 gallons before another inspection. I think I'll find that it hasn't changed that much from the last inspection.

And all that was just me being curious. I have other engines--run on that same oil--broke in at 32:1 and then switched to 40:1. Close to a hundred gallons of that oil mix through them. I haven't bothered to look inside them because there ain't nothing wrong with them. Just fuel it and fly it.

BTW--it's cheap oil compared to all the synthetics and fancy brands out there. 1 gallon costs me about $15. Thats enough to make 40 gallons of fuel if I mix it at 40:1. Pat probably knows what it is--if he remembers me from that other site.