Mid range seems lean. Idle ok, top end good. 1/4 to 1/2 throttle seems to lean out, rpm will go up and down, smoke will come and go with rpm. I have low needle 1 turn out, high speed 1 1/2 turns, regulator about 1 turn out from flush. Seems to get better as I go out with regulator, if I go in from flush with reg, idle will start to go up and down too.
Am I going the right way with this? Fuel 30% Omega helli.
Prop 11-7. I have about a gallon threw this and only about 30 min flyeing because I cannot get the engine to run right.
This is my first YS motor and any help will be greatly appreciated.

Thanks:

alextran:

Use the regulator to set the mid range mixture, then reset low and high needles as necessary.

You could well have to go back and forth a few times to get everything right, but it's worth it to have the pumped engine.

Bill.

Thanks Bill;
So turning the reg out increases the mid range mixture correct?
I'll be running it tomorrow and flyeing it I hope.

Alex:

As I remember turning it in raises the pressure. With your high and low needles so near shut I would think the pressure is too high.

Block the throttle around 1/2 and pinch the fuel hose next to the carb fuel nipple. If it immedialely drops RPM it's too lean, turn the reg screw in 1/8 turn and recheck.

But I'll almost bet it will pick up a good bit of speed, running rich.

You want to end up with the RPM remaining steady for a moment (or rising just a little bit) then falling off, when you pinch the line.

You should also bear in mind that YS engines have been known to have bad regulator diaphragms.

If you can't get it straightened out, and it is still in warranty, give it a trip back for a good check.

If it's out of warranty, replace the diaphragm.

Tower sells the engines, I don't know about their parts stock. Central Hobbies has the YS part you want, when you want it.

Hope this helps.

Bill.

PS: Some after run oils will attack the regulator diaphragm. wr.

Alextran,

turning the regulator out (counter clockwise) is to richen the mixture. regulator in (clockwise) is to lean.

Try below with Tach.

Start engine, slowly throttle up to full throttle. Set the high speed needle.

Throttle down to 3500 rpm. if the rpm drops, you are rich in the midrange. If the rpm increases and drop down, you are lean.

It sounds a little bit strange to have one turn out on the regulator and still lean.

Also, Omega (red or pink color) has castor right?

I ran my first YS with castor blend fuel (Omega), I had real hard time removing the carbon deposit.

Since then, I only use full synthetic oil fuel.

Hope this helps,

PatternFlyer:

Thanks.

Been so long I didn't remember which way was increase pressure - rich.

Bill.

I don't think that the reg increases preasure does it? Might be my mistake.

robert:

Regulator - controller - sets fuel pressure.

With the needle setting unchanged, higher pressure forces more fuel flow through the same restriction, making the overall mixture richer.

With the needle setting unchanged, lower pressure forces less fuel flow through the same restriction, making the overall mixture leaner.

And whenever the pressure is changed the needles will have to be tweaked.

This is the hard part about learning to adjust a pumped engine.

But when you get it right you will have excellent throttle response and engine power all the way up and down.

Who needs fuel injection?

And you wont want to go back to muffler pressure.

Bill.

Sorry Will, but the regulator does not set fuel pressure. Fuel pressure is set entirely by the pressure line to the tank through the check valve. The regulator is just that, a fuel flow regulator. It is a demand regulator, somewhat like the Cline regulator. But in the YS, crankcase pressure and carburetor vacuum act together to open the regulator valve. Turning the screw in (clockwise) increases the spring pressure on the regulator valve, requiring more rpm (crankcase pressure) to open the valve, thus leaning the midrange mixture. Turning the screw out (counterclockwise) decreases the spring pre-load, letting more fuel flow at lower rpm, thus richening the mixture.

I had a very similar problem with my YS 63. Dave sent me a regulator plunger with the small head. It comes with a new silicon valve seat. Once installed, all is cured.

Maybe Dave will chime in here.

Robert:

Thanks. Thought it was pressure.

Has the same effect, though, just like a Cline unit.

And it's tuned the same way.

As I said earlier, the diaphragms have been known to fail. But I didn't know there was an upgrade.

Thanks again.

Bill.

Thanks for all the replies. I finally got it running pretty good, got in about 5 flights, no problem. Sure helps knowing which way to turn the regulator and how it works. I have it in a Patric Ulitmate Bipe, now all I have to do is make it so I can tell the top from the bottom and it's good to go.

Thanks again: