That is a fascinating survey.  It is interesting that for the Kawi 440 the main failures are plug failures.  What does that mean?  Ignition system, or actual spark plug fowling/shorting out?

I have around 1000hrs on 2 strokes. 447/503/582. I did 600 on my 582, never stopped. My 447 stopped twice in around 200hrs, a loose wire on one coil, and a
seized piston due to a loose fan belt. The rest were on 503 and never a stop. I maintained the 447 and the 582. The loose wire was my fault.
The loose fan belt was due to an instructor who used my aircraft and took extra cash for basic maintenance tasks such as inspecting/tightening the belt!
I don't think that's such a bad set of stats?

OH, forgot the latest 447 failure. Unknown quantity to me. 3.5 hrs or so on the ferry flight after a lay up of 7 years. Fuel starvation due to a failed primer bulb.

That sounds like a fantastic record! One I hope I can come close to!

Stats can be tough, as getting a representative sample isn't always easy, and failures tend to get attention.  We have several folks flying 2 strokes in our EAA chapter (including myself) without issues over many years (save for a 582 gearbox failure - a used engine with an unknown history).  Actually these engines have fared much better than the certified birds in our chapter.

Personally I have owned and maintained a 447, 503 and 582 without so much as a failed spark plug.  Put about 125 hours in each bird.

my first 2-stroke was a new prov 8 503 which i flew in my rans s-17. it had dual ignition, dual carbs, and oil injection, after approx 150 hrs there was not problems. my second engine was a 277 that was used when i bought my max-103. with this engine i had 4 forced landings with the last one damaging the a/c beyond repair. i do not blame the engine because i did not maintain it properly. the first one was caused by a cracked carb boot that i should have seen, the second one was a broken mag wire, the third was because i tried different main jets and the last one was a seizure because the piston was worn out because of the previous problems. now my preflight inspection procedure goes beyond a casual look over of the engine. engines quit for a reason and most can be caught if you have a knowledge of what to look for. if you have little knowledge of what a 2-stroke need to be happy and how to carry out a complete teardown and proper inspection either read good info articles or find a mechanic that knows 2-stroke engines inside and out. now i am running another 503 in my airbike and after a complete overhaul to do an inspection i have almost 30 hrs on it so far. i am pro oil injection.

monte

Conclusion so far.

1. Build a disposable minimax for local flying with any engine.

2. Use a Rotax 503 twin carb twin ignition if you want to fly long or far.

@ Greg Doe..... How much Damage to your bird?


Also, I found a Hi Max for sale on Facebook marketplace for $5500 in Gallatin.
Fly Safe.

Mullacharjack, that's exactly what I'm about to install in G-NADS. I have a dual carb, dual plug 503 sitting in the workshop right now!

Quoted from Max SSDR

Mullacharjack, that's exactly what I'm about to install in G-NADS. I have a dual carb, dual plug 503 sitting in the workshop right now!

G-NADS.A very nice bird indeed. Any idea how much the mounting bolts need to be moved back for the heavier 503.Any need to shorten the nose?

I like the idea of the 503 but I think the Kawi 440 will be good enough to not have to sell it and move to a different engine... Here's hoping I don't come to eat those words!

I agree with the mentality that all failures happen for a reason.  I'm trying my best to absorb every bit of info about my engine that I can, and put sensors in all kinds of different places to try and catch any issues before they get bad.  Individual EGT/CHT per cylinder, carb de-icing/body temp, fuel pressure with auto redundant fuel pump, forced air cooling fan RPM, etc.  I want to try and notice as much as I can and try to catch stuff before its too late.

ITman496
                    If one were to believe the survey report of 1989 then it seems to be a good engine.With only plug failures.

I think you should ask J bird. He has been in.this hobby for a long long time and I think would be knowing all there is to know about the 440.

I've spoken with him for many, many hours about the engine.  I know he's probably biased, since he sells them, but if I remember correctly, he said that he's never heard of the CDI box failing in the air, only on the ground when ran with unplugged spark plug leads.  Otherwise, many happy fliers on that ignition system/engine with very few issues.

Meanwhile, my Max turned out to be far less badly damaged than I thought it was. No more than $70 and a couple of weekends' work will see it airborne again. I shall swap in my other ignition system complete. The plugs were fine and the compressions good. I haven't checked to see if the needle circlip broke but otherwise the carb seems ok so I am mystified. It is unlikely to be due to carb icing on a day of high pressure and having been warm for some days. I shall fix it up but it is going to be sold. It taught me a lot about flying but I need something more capable and with another seat.

"It taught me a lot about flying but I need something more capable and with another seat."

My goal after my minimax either eats it or I get bored is to build a Vans RV14.  Just need to get the garage for it..

I'm happy to hear there isnt much damage! Can you tell me what you painted your fabric with? It looks absolutely stunning!

Puff, This is the short version of the damage. Damage appears to be a crushed lower nose, crushed top of the fuselage where the roll over bar is (windshield bow), and some damage to the top of the vertical stabilized. Certainly an easy repair.  Other than that brief assessment I haven't had time to dig diaper. Still sore!

Quoted from mullacharjak

Conclusion so far.

1. Build a disposable minimax for local flying with any engine.

2. Use a Rotax 503 twin carb twin ignition if you want to fly long or far.

Perhaps....

The 503 is a good engine...I am using one now and it's been a long time since I had one fail.  My friend Paul Fiebich has flown his very long and very far, but he's had several failures, too.  Thinking that their is any engine that is "perfect" is unrealistic, and in general two strokes are less perfect than four strokes for various reasons.

Here is my conclusion so far (after doing this for 20+ years and over 1500 hours in the air)
- you will have to deal with an engine problem sooner or later
- knowing that a problem can occur at any time, you do need to be prepared to land your airplane without the engine (glider pilots do it every time they fly)
    -- Alway fly over a safe landing area to the extent possible
    -- Practice emergency landings often.  Become proficient at gliding your plane to a point on the runway so that you are successful every time
- If you have doubts that you can safely land a plane without the engine, install a BRS parachute.  

Quoted from mullacharjak

G-NADS.A very nice bird indeed. Any idea how much the mounting bolts need to be moved back for the heavier 503.Any need to shorten the nose?

I'm told it doesn't need to move? Basically it's 10lbs heavier; however I'm thinking of fitting a wing tank and abandoning the front tank. (I have the wings off right now to sort movement due to wing pin wear). Another simpler idea is to fit a bigger tail wheel (nice long arm - I'm messing around with my XL W&B prog).

Also, 503 bolt holes are different to 447, so possibly a new mounting plate (mine is alumin(i)um  

I'm tied up for a bit longer with my Electric Start business, due to a late design change but hope to get my bird in the air soon (with the new starter fitted!). Actually that provides another W&B option to balance the 503 by moving the starter battery back from it's current position under my seat.

Often heard "power pilots' banging themselves over the head saying that gliders have to land without power every time.

[see  https://www.youtube.com/watch?v=e4q6eaLn2mY for explanation]

[patronisingmode]

The fact is that gliders are really easy to land: heavy so things happen slowly, large wingspan so roll happens slowly, pilot eye viewpoint very low to the ground so a really good mental picture of the flare, and, [.............drum roll............]

air brakes control lever !!!

Brilliantly effective. Put out your arm straight out in front of you. That's your flight path. Now lower it to 45 degrees - that's your flight path with full air brake on.

And you can select any descent path in between. For controling descent rate the glider air brakes are better than any throttle control I've ever used. they have even less (near zero) effect on airspeed - which is why 'spoiler' is a better term.

[/patronisingmode]

Definitely easier to land a glider than land a Minimax with or without power in my view.

Quoted from Antoni

Definitely easier to land a glider than land a Minimax with or without power in my view.

I am surprised you think that!  Ultralights in general, and the Airbike in particular are so very easy to land without power.  One of my favorite things to do in my old Airbike was to shut down the engine over the airport, glide down to the runway, and then roll to a stop directly in front of my hangar.

Quoted from radfordc

glide down to the runway, and then roll to a stop directly in front of my hangar.

This is a requirement in the glider practical test.

Antoni

Never ever seen a minimax in person so can only guess about the visibility from the cockpit when landing.I note that all UK minimaxes look the same!

Probably because of the cold wind.Looks like the visibility from a closed cockpit might not be optimal.

With the open cockpit minimax the visibility and mental picture for flare should not be a problem but you might be knowing better.

Also cant the max be side slipped which should be as good as the spoilers in gliders.

You don't need to sideslip a Max. They land short and lose height very easily. Visibility is fine from a closed cockpit.

They DO side slip however although not like my Taylorcraft . When I flew the 'Max back I had only completed a couple of landings and arrived at one of the farm strip fuel stops too high. I side slipped without thinking and found it quite effective although nowhere near as dramatic as a full on slip in the BC12-D with rudder vibrating and fully crossed controls, dropping like a stone!

There's a bona bide Sky God for you - flying a 'Max without thinking! Takes me most of my consciousness!

UK Minimaxs look the same or very similar becaause of UK microlight regulations on how they should be built. The regulations probably saved my neck on one occasion (thank you Mr. Donaldson). The regulations are much lighter now but that is a very different discussion.

Minimaxs side slip superbly! Even horizontally along the runway if you come in too fast because you realised you've cut-in into the circuit in front of some-one else!

The forward view from all Minimaxs is fine, but your eyes are much higher above the ground in a powered aircraft than they would be in a glider. Surprising how easy it is to flare and land gliders.

My point is that being able to land a glider does not equip you to dead-stick land a powered 'plane.

Quoted from tomshep

.....flying a 'Max without thinking! Takes me most of my consciousness!

Then go up a few times before you sell it and just unclench your botty and play with the thing!

They are really friendly!

Quoted from tomshep

There's a bona bide Sky God for you - flying a 'Max without thinking! Takes me most of my consciousness!

No Tom, all the Sky Gods live on the Flyer Forum  

Quoted from Antoni

Then go up a few times before you sell it and just unclench your botty and play with the thing!

They are really friendly!

Thou shalt not go beyond 30 degrees in pitch and 60 degrees in roll what it says.

I guess there is not much room for play left,is there.

In my ultralights I've never exceeded 360 degrees of pitch and roll!

I would say there is room to play.

Quoted from Antoni

My point is that being able to land a glider does not equip you to dead-stick land a powered 'plane.

I have flown a glider.  I think an experienced ultralight pilot could land a glider easier than a glider pilot could land an ultralight.

Gliders don't have very much drag, and they use the spoilers/flaps for glide path control.  This gives them the ability to be high or low off the best glide path and still get back to it. But gliders still land relatively fast and use a good amount of runway to stop.  

Ultralights have drag in abundance.  Glide path control in an ultralight means staying above the best glide path at all times during the approach.  With extra speed and altitude it's a matter of just pointing the nose where you want to land.  If you're high you slip off the altitude. When you reach the runway and round out an ultralight slows immediately and is stopped within a couple hundred feet.  Typically, pilots with no ultralight experience find themselves too slow and too low during landing.

But, I have over a thousand hours of ultralight experience and only a couple of glider flights so I am naturally most comfortable with what I am used to.  But, my point (before we took the glider detour) is that if you fly an aircraft that uses an engine that is known to quit unexpectedly you should be prepared for that to happen.  You should know that you can land successfully without an engine, and the best way to know is to practice.