os 50 went bang!!

[paul35]

well after about 3 weeks of no flying, i finally got chance to go today

but only managed 1 & half flights before the engine went pop

is it worth changing the piston liner whist i'm replacing the piston it doesn't look scored in anyway

[Mart61]

If it ain't scored, don't change it.

If it is scored, hone it.

[davec_7]

Is the head OK as this is about £70 to replace, a piston ring about £17, piston about £27. Con rod £8. I've been in this dilema a couple of times myself and each time I purchased other engines. At least with a new one you know you will have a reliable power source. Its a tricky one.

I would suggest if your unsure you get somebody to have a look at it for. I hope you managed to get your heli down in one piece.

[paul35]

yeah the head looks ok a little black, but ok, i'm thinking time i've replaced the piston, piston ring, con rod, might as well do the bearings as well is it worth just getting a new motor

yeah landed the heli fine

[pgkevet]

And don't forget to flush, flush, flush the muffler!!!!

[Geek]

Was that caused by a lean run?
looks like it got hot by the colour of the piston.

[Paulice]

Like me on a saturday night "Pis-ton broke"

Looks like a very lean run, and the over heating caused the alloy to melt.
what are your needle settings?

[paul35]

yeah it went lean, the nipple on the muffler had worked it self loose, although it was still attached by a thread or 2, i assume thats what caused it anyway

[paul35]

main needle 1 & 1/2 turns out, it has been fine for the best part of a year and always just warm on the back plate except today when its was smoking

[Geek]

main needle 1 & 1/2 turns out, it has been fine for the best part of a year and always just warm on the back plate except today when its was smoking

I needed to richen up in the cold

[paul35]

might be why it went lean then, i've not touched the needle since i fitted the engine last year as its never given any problems, lesson learnt today

[Geek]

might be why it went lean then, i've not touched the needle since i fitted the engine last year as its never given any problems, lesson learnt today

Because there is more oxegen in the cold air you need more fuel to run it at the correct ratio.

Not sure how old you are and if you drive a car.
but if you drove a car with a choke you need it more in cold weather

[davec_7]

If you've already replaced all these items its probably not worth getting another engine, but certainly check both the bearings as these are easily replaced by warming the engine in the oven after first taking off the carb and O ring. Make sure you give everything a good wash out several times, checking each time that there are no particals present in the solution used. I usually use fuel.

Always check the temperature of the motor after each flight by putting your finger on the back plate it should ideally only be warm, better to run it a bit rich rather than too lean.
Good luck
Dave

[paul35]

yeah i've had a couple of cars with chokes, never even entered my head with my heli engine

new engine come payday

[choppaholic]

i have piston ring and liner if you want them or an entire engine minus the crank, they came of a engine which had done 4 gallons, i was changing the back bearing on it when i got the crank out the bearing was stuck to the conrod so i tried to get it out but bent the crank shaft so have the whole engine as spare.