Engine Just Stopped!

[Steve]

I went flying this evening with my Airskipper 50, flew around for about 3 minutes, came back to a hover over the strip, and the engine just stopped. Landed it ok and no damage.

The engine stopped completely without warning - no change of note, no hunting etc. The model was being flown for the first time with a brand new RevLock fitted, which for the 3 minutes or so that I flew it, was working a treat.

I tried it again with a new plug (not that there was anything wrong with the old one), and it just wouldn't start.

My first thoughts were - oh dear (or words to that affect!), I've killed another engine, but close inspection back at home reveals that the inside of the engine is fine.

The engine is my YS50, which has the positive pressure fuel system and a regulated carb. The one-way valve is fine, the crap-trap filter is clean as a whistle and the engine internals are fine.

Now, the bit that I don't understand, and therefore can't figure out if it's working ok or not, is the regulated carb. I've had it apart, and again it all looks fine, but I don't really understand how it works, so the answer could be staring me in the face, and I'd never know it.

Unlike the OS50 engine, if you try to blow down the fuel tube into the carb, you can't. There's a tiny sprung loaded flap valve just inside the fuel nipple which defaults to shut. If you press the flap valve with your finger, then you can blow through the pipe as you'd expect.

Can anyone shed any light on this, and in particular the YS regulated carb?

BTW - the fuel is thae same Cool Power 15% that I always run now, so no change there.

A bit long-winded I'm afraid, but I've tried to put as much info as I can give.

Thanks.

[Steve]

Any ideas?

[Nutz]

This is not what you want to hear and does not really help you but,

A friend had the same problem with his YS (in a large plane) as you just described, he had the regulator apart a few times trying to figure it out, in the end he sent it back to the specialist (twice as it went wrong again), I still don't know if he got it fully sorted out or not.

[Ade_Law]

firstly have you check the basics? clunk lines in header and main tank? if they go soft i have seen sudder quits like this.

if the 50 is the same as the 90 then behind the diaphragm there is a pin hole that goes into the crankcase where the hole in the crank for the carb is. when the crank lines up with the hole the crankcase pressure opens valve and lets some fuel through. so you could try replacing the diaphragm. if you can get one!

Ade

[Steve]

firstly have you check the basics? clunk lines in header and main tank? if they go soft i have seen sudder quits like this.

if the 50 is the same as the 90 then behind the diaphragm there is a pin hole that goes into the crankcase where the hole in the crank for the carb is. when the crank lines up with the hole the crankcase pressure opens valve and lets some fuel through. so you could try replacing the diaphragm. if you can get one!

Ade

Yes, I've checked the basics. The clunk line in the header was rather mushy and needed changing, but the header remained full of fuel, so there should logicaly have been no loss in delivery.

I checked it over last night without taking it out of the model, but I think I will do when I get a chance at the weekend, and go over it with a finer tooth comb.

As for parts availability - John Haytree will be my first port of call if I need anything.

[Steve]

Oh bugger!

I've had the engine out of the airframe this evening and looked at its 'inerds a bit more closely........

...... piston, ring and liner are all capput.

Pushed it just a little bit to hard...... again!

Will be interesting to see the difference in price for these bits compared to the Hyper, and of course how easy they are to get hold of.

[ChrisB]

How do you mean,pushed it a little bit too hard?

Hyper 50`s take some serious abuse and hold up fine except for occasional rear bearing replacements

[Arky]

not with a lean run they don't Chris

[Steve]

Exactly.

[Steve]

I made some phone calls this afternoon in pursuit of a supplier of YS engine spares.

Finally found one, and the three spares I need come to £35.

The same three parts for the OS50 Hyper are £75!

Result! (provided they have the bits in stock of course)!

https://www.probuild-uk.co.uk/

We'll see how good they are.

[Ade_Law]

dont use probuild... please.....

Ade

[Steve]

dont use probuild... please.....

Ade

First of all Ade, why not?

And second, if not then where for YS spares?

[robgt]

piston, ring and liner

£35 for that lot is very good
Cheers,
Rob

[Steve]

£35 for that lot is very good
Cheers,
Rob

Quite right Rob.

Motors & Rotors wanted £65 for the same 3 parts this afternoon, and they had them in stock.

What's Ade's beef with Probuild?

[robgt]

Dunno?
Cheers,
Rob