I ran in my DL50 on a 22 x 10 Zinger as i didnt have a mejzlik to hand. Speed was no different from a 22 x 8 but definately had more 'pull' vertically. Not sure if that helps much? []

I use a 20-12 Menz

Hello all,

When engine over heats, how does it get damaged and what part usually gets damaged the most.

Thanks

Sleeve scoring, ring seizing, crankshaft bearings, crankshaft seizing, con-rod end bearing failures. Probably in that order.
None of them "good things"

Bob,

You left out the piston, aluminum pieces can flake of the piston and cause scoring to it self and cylinder walls as well, Not a good thing to have happen to your engine.

Yep. Intentional.
By the time the piston is self-destructing, usually some, or all, of those other fatal occurrences have happened.
At any rate, you will have to buy several new parts if these things happen. Minimum.

wonder if any one can help, have dl going back to wholesaler(who i must say has been fantastic in his aftersales service and care),
but thought i might ask anyway. my dl-50 was going real strong, then i went to fly the next day and the power just wasn't there. dropped abount 1000rpm, but felt like it was lacking tourque all through the rev range. retuned motor runs good but still lacking power,
ing is fine, no blockages or crap in filters, piston and sleeve not worn. mine question is what else can cause this? reed valves? or a leaking front bearing? if one petel on the reed valve was stuck shut would that give simular effects to my problem? how can you tell if ring is worn? and could it be this?

Any compression cold?

i can turn it over by habd no problems with prop off, it does make a nice pop when you turn it around, doesn't feel any worse than when i got it.

although it doesn't have the compression of my glow engines that makes sense.

Pull the plug, check the gap. Carbon/oil/electrode shape?

pretty new plug, it's not all black, it's mostly a browny color, plug gap is .02", loose fit with feeler gauge, tried another plug too with same results but that has same gap. they seem to come with a bigger gap than needed as mine have always come with more than .02" gap

Well. Based on what you've said so far, I'd have to speculate ring/sleeve wear and subsequent loss of power when hot.
Pure speculation, could be many things.
1000 rpm drop is a ton.

i hear you, thanks bro! engine feels the same even when i start it from cold, so i feel it's not only when hot! does that change things? what about the petel valves?

Two things you can do as well,

Take the muffler off and inspect the piston and ring from the exhaust port for anything unusual,

Or remove the head four screws and it will slide out for inspection,

bosco 2, i took off head last night to have a look, dont think i know enough about the wear i engines, but there was no rough scratchers or groves in cylinder or on piston, just looked like normal wearing in marks to me. but like i said maybe it has worn beyond tolerances that i can measure. didn't know what to look for on ring, although it looks a little worn but not bad or grooved or anything.

What color is the piston is it black or dark brown on the sides,

a light brown is the norm, along the sides the top will be black with carbon,

piston on top is black, a bit dry looking. on sides it is not really black or brown, it looks pretty clean and i could see/feel oil film, i would say it was slightly brown. above ring it is brown, ring is slighty brown to

Im sure that you have inspected the spak plug wire and cap for any problems, check to see if the timming sensor has not come loose or moved check to see if any trash is in there if the timming is off that will cause lost of power,
If all that checks OK than I would give my fuel system a good looking into especially the fillter,

From what you have said so far I do not think you have toasted the engine,

I tend to agree. Everything stated so far sounds like good mechanicals in the engine. I tend to think the timing sensor could be more likely, as a fuel flow issue would probably show up as a lean or erratic transition/throttling problem.
Interesting discussion.

Other than RPM drop, does it run consistently in th low and middle range? If the RPM is not steady, there is a leak somewhere. Double check the two bolts holding the carb to the crankcase, and the cap screws on the carb.

Did you get a chance to take out the cylinder and see if there are blow-by signs on the wall? Does the engine run very hot (hard to touch)?


In a recent flight, the high RPM droped considerably on my DL50 and the compression was almost gone. It turned out the ring was rotating on the piston and worn excessively. A pair of new piston and ring fixed the problem.

ring is not turning on piston as ring is held in place by the pin in the piston, checked that. i think it's possible that timing senor may have moved abit as screws could be tightened about half a turn each, i dont know how much movement matters though. if it moved 1mm would it make a big difference? i think this is the key to my problem here! engine runs like a clock, very smooth and consitant at any rpm, even full throttle. just not pulling hard. feels low in power at all throttle positions. it used to feel like it would rip my arm off at full throttle when i used to rev it on the ground, now it's more like a firm pull.

checked over fuel system, all looks good. fuel lines are not blocked or kinked. cleaned fuel filter, there was no gunk in it, also i have a filter on my fuel pick up in my field bottle. flows in and out of tank easily and fast.

A 1mm difference in the sensor is several degrees. You should be able to easily determine if the bracket has slipped on the crankcase.
Regardless, I would check the timing, just to see where it is. On a Brison I had once, a very small difference in the sensor really made a LARGE difference in top end. But it also affected ease of starting.

how do you detirmine if bracket has slipped? i checked the bracket and there were no old screw indentation where it was tightened on from factory, is there a way to check where it should be? what degree are they set from factory?