The YS 110 is fully broken in. One day she runs good and the next day she doesnt. I flew it a couple of weeks ago and you will be flying and pull straight up and give it the throttle and the motor just quits in a split second. Basically the prop just stops.

Tuesday I went flying and flew it three times. I was down on the deck hovering and doing harriers and all kind of manuvers. The motor was just a bit rich so i adjusted it and flew again and it flew a lot better. Nothing went wrong Tuesday.

Today I was flying and pulled up for a hover and started doing the same thing it did before. I adjusted the bottom screw a little and probably dead stick the plane 3-5 times today. I finally gave up and wanted to post it on here. I am getting a lot of air bubbles. Also I think it is just over loading with fuel because when the plane stops on the ground a couple of drops of fuel run out.

I plan tonight to watch a Model Sport Video I have and it has a YS engine on there to learn more about the engine. YS is just totally a whole different engine. I know my granddad so far does not like it. He likes it when it runs good but when it does what it is doing he hates it. He examined the engine and he determine the OS four strokes are way better built and better design. He has been around this hobby for about 30-40 years.

By the way I have this engine on a 70 Size Katana from TMPRO the profile.

Did you find anything out Kev?

BTW: A lot of bubbles can't be good, maybe your tank isn't floating enough. Still doesn't account for it running good one day and bad the next. Put the needles back to factory settings and start over.

YS's are different animals and cant be treated like any other engine. I'll go over the obvious first:

1. are you using the right fuel? YS 20/20 is preferred or 30% heli
2. do you have dirt in the engine anywhere? Using a fuel filter is preferred with YS's
3. Do any of the hoses have any cracks? Airleak anywhere?
4. Are the check valves working correctly?
5. Replace the Diaphram? Using the wrong fuel can damage it causing an airleak which might cause the dead sticks.
6. are you too lean? YS needles dont need too much movement to get optimized once broken in.
7. Are you releasing the vent line after each flight?

My friends YS 120 was on a 1/4 scale Sukhoi and left in a garage for 2 years untouched. After priming it it started quickly and served without touching the needles the entire season! Treat them well and they will reward you. Mine are finicky but once dialed in you never mess with them. I have 5 of them and swear by them now. Much preferred over my Saito's and OS's



good luck

I'll second that--the YS, when dialed in, is a much smoother, better-running engine than other 4 strokes. check out http://www.geistware.com/rcmodeling/...er/ys_main.htm for great info on YS