Have one of the new 140 Sports. have about 1 gallon through it, Cool Power 20% Pro pattern (20% oil). Needles set per factory instructions. OS-F plug.

When I start the engine, it starts and idles fine. Run up to full throttle is OK for about the first 30 seconds or so (until pressure builds in the tank). AFter that it goes extrememly rich in the midrang, so much that it usually sputters and quits. And after it quits fuel drops out of the carb (inverted) and is all over the ground. When it will run, you can feel raw fuel blowing out of the carb at almost every throttle setting. No amount of needle adjustment can seem to get rid of this (high and low speed needles). I've backed the low out so far that it almost falls out.

I left the regulator as it was from the factory, and had this problem. (appx .5-1 mm above the housing) One of folks really good with YS engines took a look at it at the last pattern meet and told me he thought the regulator was clogged and sticking open. So last night I took it all apart and washed everything in clean fuel. Couldn't find any debris whatsoever. I put it all back together, set the regulator flush this time, and I'm having the same problem. What to do? Thanks in advance, chuck

The plunger is not sealing. Try running the regulator screw in about 2 turns and see what it does. There could be a casting flaw in the seat where the plunger sits which allows fuel to leak past it. If screwing the reg in doesn't do it, we will have to see the engine.

Got around to working with the engine yesterday. Somewhere around 2 and 2 1/2 turns, the regulator screw bottomed. I ran it at that setting and it seemed to be OK. Engine is much tamer now. About the only thing I notice is that a couple of drops of fuel come out of the carb when I shut down. And there is still some spray over the bottom of the airplane suggesting that some fuel comes from teh carb in flight. This may be normal.. I'm a new YS person (as you can probably tell)...

Question is it safe (and normal) to run with regulator closed fully, or should I send it in? TIA, Chuck

It's really not right, but if it runs ok, go ahead and continue running it. The excess fuel coming from the carb could mean too rich. Where is the main needle set?

Main needle is at appx 1 3/4. That is a fairly rich setting on this engine, as I only have about 5 good tanks through it right now so I've been keeping it fat. But it looks like peak rpm is around 1 1/2. Seems a little tight to me. My gut says that I'm about 300-500 off of peak at the needle setting that I'm running right now. But I haven't tached it so can't tell you for sure.

Sound good or shall I send it in? Thanks for your quick replies! Chuck

YS engines like to be run close to the peak. Normally about 2 or 3 clicks back from fully lean is where they like to run.. Your setting should be rich and you can sneak it in as the engine breaks in. After you run a couple of gallons through it, it will calm down.