MAVROS

Hi all I am in the proccess of breaking in a new YS170 CDI
I have run the engine with 20% Nitro and 20% LS oil for about 2liters at 2.5 turns on the needlle.
The engine starts first go and runs nicely at low rpm but when I advance the throtle it starts to misfire badly and stops.I have put the needle back to 2 turns but still misfiring.

Is this normal for new engine or is it still too rich.........YS recommends 2 turns however this sounds a bit too rich

Also can anyone recommend a place to buy a good spark plug for such engine...the one with engine is Chinese chicken s$&*(

THANK YOU IN ADVANCE FOR ANY ADVICE

Rgds

MAVROS
AUSTRALIA

riot3d

With cdi you can pretty much lean it down to one turn or slightly less, at least on mine with Coolpower 30% heli with 23% oil after break in.

There is nothing wrong with the stock YS plug. Although, it doesn't last as long as the after market one like NGK ME-8 or the Rimfire VR-2. The YS one will start misfiring after about 30 flights sometime, the key is to file the tip of the electrode to a slightly pointed shape when new, check the gap & clean the tip on a regular bases.

I have tried all three brands on both 170 & 175 cdi & prefer the Rimfire, it's the most consistent by far.

Hope this helps,

Adrian

bjr_93tz

2.5 turns out on the main needle is huge rich, I'm about 24 clicks out which from memory is about a turn or less. Regulator is about flush but that has varied a lot depending on the differnt versions of diaphragms that has been fitted over the time.

Everyone is different but I found even 12.5% oil a bit too high for my liking, needing to set the needle and reg super lean to avoid loading up and occasional misfiring. Running 10% oil I can run it richer on the needle and reg without it misfiring. I managed ~50 flights on the OEM plug before having to regap it. Symptons were it was developing an occasional misfire pushing out over loops and humpty bumps, where before I'd start to lean the needle I went straight to the plug, regapped it and misfire went away...

After a rebuild, I put up about 10 flights with a 17x13 which lets its rev out to about 8K, then swap out to my regular prop which turns at about 7.2K

I'm always learning something with this motor...

Oh and another tip, if it has loaded up with oil on the ground and the engine is inverted in the plane, try advancing the throttle to just before it starts to misfire, then pick up the plane and hold it upside down over your head. I've had to do that before to clear the oil from the tappet cover, as the rpm increases it starts to pick up oil pooling in the tappet cover, tricking you into thinking it's rich when it's actually oil fouling the plug.

drac1

My Feedback: (4)

It won't run any good at 2 1/2 turns. Rough running in the transition is too rich on the reg. Lean the reg. out 'till the transition is smooth without the engine trying to jump out of the model.

Be careful when leaning the top end as if it runs lean it will spit everything off the front and possibly break the cowl.

My settings.

30% nitro,
9% oil,
Needle 7/8 th of a turn out,
Reg. is out to the start of the bevel on the brass adjusting screw,
Keep the plug gap tight. 0.0"10-.0.012"
APC 19x11
YS plug seems ok.

apereira

Mavros,

As all of the above, the setting is extremely rich, I break in the engines at 1.5 turns, then usually run at 1 turn, I run my engines rich always. Try that first, but what you are experiencing it might be a bad spark plug.

Regards

Alejandro P.

MAVROS

Hi all,

Your advice is very much appreciated...............I will try it all and report back to you

Once again thank you so much

rgads

MAVROS

MAVROS

Hi all,

Thank you so much for your advice.
I have leaned the high speed needle to just over one turn and changed the spark plug .
The engine runs well now but I think is still a little tight

Put in 5 flights and so far so good but I notice that it doesnt want to start until it cools down after flight......maybe getting too hot

regards

MAVROS

apereira

Open it 1/4 turn and try again, I close my needle valve just until stops misfiring, I do use it rich.

flyncajun

apereira is correct
here are a few tips from Me.

The pump is the most important adjustment.
If it`s running hot on break in, Most likely you are lean on the bottom and rich on the top.

If your engine is not stumbling on the low end to mid range throttle advance, turn the pump out 1/4 turn at a time first before you adjust the high speed needle.
The pump is very important and has to run as rich as possible or you will wear it pematurely. the pump is the first adjustment ,and the heart of the setting.
Engine stumble will break your plug ceramic, and prematurely wear the Cap and wire to the module , also slip the spinner backplate on the thrust washer and ruin the spinner and thrustwasher,

If the spark is weak , Or plug is bad, plug cap is loose, pump is too lean, Ignition box faulty, or the high needle open less than one turn. after break in
the Engine will run hot!

Baffling helps but after setting the engine right ,you won`t need the baffling. it will run as cool as the non cdi version If you try to set it uptoo lean it runs Hot.
It will fool you because it will perform fine in the air But vapor lock on the ground on cool down.
Make sure the plug wire does not rub the fire wall , protect it with foam tape ,and secure it to the intake tube so it does not whip around and it will last longer


Bryan