Teaching the correct way to break-in an engine

[RCFlyer55]

I know there have been threads on tuning an engine. But non on breaking one in. With all the new 50cc's on the market seems like everyone is moving to gas. I would say 1 out of every 4 flyer's at my fields have one. The only problem is most have no idea how to use them. They have the Glow mentality. I saw one going in on the low end with a screw driver with the engine running. That could have been some mess. I know there are many FAR more qualified people on here then myself to do a thread on it. Perhaps even a video in the how-to section on both breaking-in and tuning a gas engine.

Just an idea.

[Biff]

Corker of an idea! In fairness across the boards, how about we post brand specific recommendations? That way we have it straight from the horse's mouth. Honestly I'm not sure they all suggest the same!

[RappyMan]

I got a chuckle out of this in the BME engine manual:
Note: This is not a glow engine and it is not a good idea to run the engine too rich as it will generate carbon deposits, foul the spark plugs and may cause the piston rings to seize on the pistons.

It's a great thing to post though - after years of running glow engines, it just seems like you need to run them rich.

[Biff]

Good catch Rappyman!! That's what we need to spead the word about! The 50cc market is the logical choice for a first gasser. For safe problem free operation,we need to share what the manufacturerers have to say. Thanks for adding that!

Another thing is safety!! DO NOT ADJUST ANY GASSER WHILE IT'S RUNNING!! If you need to change the needles, make the change and start it up. If more adjustment is required, shut it off and adjust. NEVER while it's running! Also NEVER NEVER NEVER start a gasser by yourself. I've been chased by a gasser 1 time. The linkage to the throttle was broken and I didn't know it. The motor came up to full RPM and I had a hand hold of the wing. The thing chased me around in circles until a buddy grabbed it. You do not want a prop that large chasing you into the sunset. Scared me to death. NEVER again!

I've seen two guys go to the hospital over starting big planes by themselves. The chances of a servo or linkage failing are slim but just imagine what could happen. You need to approach EVERY airplane with caution. I've seen stitches from a foamie.

Giant scale planes as well as choppers and foamies have the potential for great damage. Take NO shortcuts on safety!!!

[dick hanson]

the engines with carbs at the rear, are easy to safely adjust whilst running
Providing --you setup sleeves to orient your screwdriver to to needles.
starting and other safety issues tho are not to be taken lightly - always have an assistant holding the plane or watching the plane if a stooge holding device is utilized.
as for breakin--once you have learned how to adjust the needles properly - on a bench -put the engine in a plane and fly it
Otherwise you are just using fuel and likely doing more harm than good .
why?
proper break in equires varying engine speed and allowing it to unload in the air - rpm won't hurt it but full throttle on a bench can wreck any engine if allowed to heat -and heat comes on fast - in seconds-not minutes .

[50%PITTS]

I for one would love to see something on breaking in and adjustment of ZDZ 2 cylinder engines! That would always be helpful!! Maybe even a step by step video????

[Kiwi]

Dick,

Hands down yours is the best advise so far.

I'm on a lunch break so no rambling novels this time but heres my opinion on running in gas engines.

The number one and absolutely critical part is the oil mix. READ THE MANUFACTURERS RECOMMENDATIONS AND DONT MESS WITH IT.

If you happen to be a long way off the beaten track like me and you cannot get lawnboy or Amsoil etc then use the best mineral based two stroke oil you can find. Any reputable chainsaw manufacturer or oil manufacturer will be OK. Remember these guys sell more saw engines than RC will ever see so they know whats cool and whats not. Plus half the RC engines on the market today are built from saw engine barrels and pistons.

DO NOT!!!! run the mixture rich as excess fuel will wash the cylinder walls with the excessive gas and that breaks down the oil film. That equals heat, wear and eventually seizure. But at the same time dont what ever you do run the engine lean. My ideal is to tune the engine so it peaks the high RPM and holds it for 20 seconds or so. The hold is critical as when you bash the throttle to full the engine will suck a slightly richer mixture and you think you have it set. Dont beleive it. Run your full throttle for that 20 seconds and make sure it does not lean out or loose rpm on you.

OK now go fly. The mixture you have just set is all wrong once your flying and the air turbulence, ram air effect etc starts to come into play. Fly your first flight doing some nice easy stuff. No hovering etc. Listen to the engine and vary the throttle use all the way through the range. As often as possible. If your engine burbles a little in the mid range leave it. Dont try to lean it out yet what ever you do. But make sure at your full throttle setting the engine has power and does not fade. Fade is generally a lean mixture. If it fades on a vertical up line land and open the high needle an 1/8th or so. A little at a time is what works. Once your happy that your engine is running good (I did not say perfect) go fly your 5 gallons or so. Every flight the engine will sound better and run better. It will get more and more powerful as the bearings, rings etc bed in. Above all be patient with it.

Another small observation I have made over the eons is when the engine is new you will get a fair amount of black residue in the mufflers. That is normal as all the wearing in is producing a fair percentage of that stuff. Once you get that first three or four gallons through it it will go away and at best you will end up with just black dry soot. When you get that your engine is pretty much ready for the next step.

That means going and adhering strictly to the manufacturers recommendations. If they say 100:1 do it. If they say 80:1 do it.

But most of all tuning a gas engine is a long process. The good part is once you have it you very rarely ever need to go play with it again. It's set for life so to speak.

Now I missed lunch again>!!!


Kiwi

[JoeAirPort]

Very interesting timing for this thread (for me). I just got back from the field after a dozen flights (lost track). This is my first gasser, a BME Edge 30% with a new DA 50. I was totally confused until today about how to adjust these gas engines. A few months ago I read Xipp's post on how to tune a Waldbro, and to be honest, it totally confused me. So I dug into other forums and picked up tid bits here and there. The part that Kiwi covered on the high needle tuning is something I just learned in the past two days. So today in the morning (strong coffee) I went back to Xipp's thread and read that again. It all kind of fell together. First I just did what Kiwi said on the high needle and it worked great. Then I dropped the throttle down to 1/2 and it was 4 cycling. I just leaned the low needle until it went away (rear carb, very safe when running). Then I dropped it to 1/4 throttle and it was 4 cycling again. I leaned it more. Then I checked for transition, wow, quick. Then I checked full throttle, no fade (didn't want to lean it any more). After that I flew it and man what a change. Absolute instant power, no 4 cycling at all in the throttle curve. The idle was very stable when I chopped the throttle so no fear of dead sticks (at idle). That engine ran so well that I started to do all the 3D stuff and the engine never hickuped. Even brought it down on the deck. But I was sure to get the plane moving again after a harrier to keep the engine cool. Also my fuel consumption went from almost 16 ounces in 8 minutes to around 8 ounces in 8 minutes. The gas guzzling settings were what DA recommends for starting points. My experience is that they are way too rich.

Many people say to peak the engine's RPM and back it off a 1/4 turn or 300 RPM etc. That is NOT the right way to do it. What Kiwi described is what DA told me to do. Unfortunatley they did not explain to me how to do the low end, Xipp takes credit for that. Thanks Xipp !!!! Here's a link to Xipp's thread.

Gas engine tuning for newbies....

[RCFlyer55]

	Quote: Originally Posted by Biff
	I've been chased by a gasser 1 time. The linkage to the throttle was broken and I didn't know it. The motor came up to full RPM and I had a hand hold of the wing. The thing chased me around in circles until a buddy grabbed it. You do not want a prop that large chasing you into the sunset. Scared me to death. NEVER again!

Biff must have looked like he belonged in the PBA, but he was missing the clowns.

But seriously, it ain't a joke. I went over to the guy and politely suggested he shut it down and pointed out the wind blowing his jacket towards the prop. But he failed to listen, so I just stood clear and hoped for the best. then brought up field safety at the next meeting without pointing fingers.

Great advice Kiwi, thanks for the post.

[Jim Woodward]

I've always followed the practice of running on the ground in short runs with varing throttle positions. After maybe 5 short 3-4 minute runs with cooling inbetween, go to the field and fly if set close enough. I had heard long ago that the heating/cooling cycle(s) was important to the molecular structure of the motor, as well as the cutting-in done within the initial runs of the motor of the internal parts. Yes though, excessive heat is bad and to be avovided. After a few short runs, check the bolts and fly.

Jim W.

[RTK]

I disagree with extended WOT runs on the ground or bench seeing if it will SAG. You might be able to get away with this on single cylinder engines,,, but twins seem to generate a lot more heat. I have personally watched people do damage to there new twins doing just what was described.
Poor air flow + lean condition = disaster
Then people complain about what a POS the engine is. Check for sagging on an up-line.
Make sure the engine runs well on the ground to avoid any dead sticks and then fly it. Do all you adjusting by how it runs in the air not on the ground.

[JoeAirPort]

The key word in your reply is "extended". That's what kills them. Gotta let them cool down between adjustments. You can use any good method, do it wrong, and ruin an engine. It worked simply awesome for me.

BTW I got my method from a guy who knows engines well (Xipp - Sala engine mod's).

Gas engine tuning for newbies....