Somewhat like posted earlier by another modeler, my 63 is running rich.

Tried running the low end needle at 1 1/2 turns out but to get it to even idle and transition well it has to be almost turned out so that the head of the screw is almost flush with the carb.

I have had the carb fill with fuel during some startups.

Tried setting the idle screw at 1 1/2 turns and tried to adjust regulator pressure so that I had a decent idle. Top end would suffer.

When I can get a good top end it will tach at about 10600.

Took everything apart and checked for debris but only found a slight burr on the carb barrel in the v cut and cleaned that.

At this point I have not checked valve clearance with a gage, but I did check it yesterday to make sure that there was some. Yesterday it appeared to have about the same clearance on both intake and exhaust, but today the intake appeared to have almost none.

What is correct valve clearance on the 63? How much side play should the rocker arms have?

Engine is mounted in a Something Extra ARF with the factory motor mounts mounted upright.

Prop is a Master Airscrew 12x8, fuel was a new gallon of cool power 15% with 2 oz of redmax oil added.

All fuel tubing has been changed and tank has been replaced.

I can get it running ok fly and come back and cannot get it started..

What else is there to check? I have seen little on how to adjust the regulator pressure and when, what is correct?

Have I covered everything? Do I have an oring or seal that is bad?

Set the valves at .003". Put an 11x7 or 11x8 prop on it and get some good 20% fuel. You sound like you are overpropped and underfueled.

Dave

Thanks, I picked up on the .003 from more searching. Seems far from what the manual recommends (0-0.1?). This is adjusted cold correct?

I take it that the excess fuel in carb could be from misadjusted regulator or something "broke" in the regulator if it can not be adjusted out of this condition? I'll start with the screw "flush" again after checking valves and changing prop size.

Cold is correct. The manual is METRIC! .05 to .1 mmm is roughly .002 to .004 INCHES. We set them at .003" Right in the middle.
Thr reg. might just have a piece of crap in it. You might want to take it apart and check it out.

Good Luck,

Dave

The regulator screw will come out correct? Or do you clean the regulator by removing the housing? I unscrewed it and it did not seem to want to come out and I was not sure so I did't try to force it. It may have been being retained by the o ring.

Metric, ok makes sense. I went back out last evening and checked with a .003 feeler gauge and was just a bit loose. Feeler gauge slid in with minium friction if any. I think I'm ok here.

Prop, fuel, and I might as well throw in a plug to make sure.

Pull on the screw, the o-ring is holding it in. You need to take the housing off the engine as well.

Ok, just getting back to this problem.. now that nicer weather is here..

Did as you suggested but still having problems.

Checking everything I can, but I may have found the problem.


On the bottom of the carb barrel opening there are 2 holes. I'm making the assumption that when the carb barrel rotates to idle that the fuel is directed thru this port. I'm hoping that you will tell me that this should vent to the hole just below the barrel on the side below the intake tube. You can view these 2 holes really well from the high speed needle valve side.

If this is correct then I'm thinking I may have a bad carb body as I cannot get anything thru these openings, spray cleaner etc. I have tried really fine wire to make sure it is clear but nothing wants to go thru..

Waiting for you reply

You really need to call me. 775-265-7523

Dave

I got my 63 back from YS, thanks for the fast return.

Overall it seems to be running much better but I must be still starving it for fuel during certain maneuvers. It will run along fine and during a dive or tight spin it will cough and sputter till it gets fuel again. I’m assuming this is what is happening.

Do you think a header thank such as what we use on helis would be of any value? Or is my tank still not right? It is the second one I have put together for this problem, but I might still be missing something. Pressure seems to be holding as when I come back to the plane after sitting for awhile it still has pressure.

Outside of highspeed adjustment and slight lowspeed adjustment we have not changed anything since it has been back.

With the high pressure of the YS, you don't need a header tank.

What throttle setting when you dive or spin? You may be overspeeding the engine which will cause a miss.

Maybe a Tettra type tank is in your future.

tetra bubbleless type I assume?

in the dive, maybe half to 3/4 throttle, in the spins I would say idle or just above.

1/2 turn counter-clockwise on the regulator might help.

Thanks dave, will give it ago next time out..

Ah heck...

Ok Dave, couple of more questions...

First, when the fuel line is disconnected from the carb and the engine is turned over buy the starter should the pump be pumping fuel into the carb?

Second, when the regulator is disassembled should fuel be on both sides of the diaphragm?


Reason asking, is I get no fuel and when we pulled the line from the carb. And when we checked the regulator and reassembled it pumped for a short bit then quit again.

We think we have it narrowed down to this area of the engine, diaphragm did not appear to have any holes when held next to a light but I will check with a magnifier tonight. I'm guessing this is going to be a part that I might want to keep on hand?

A friend noted he thought the high speed needle might be too sensitive. (lack of fuel maybe?)

Had one bad run first time up, then 2 great flights, then last 2 it coughed and poked along.

You can't spin it fast enough with the starter to make it pump a significant amount of fuel.

Yes.

Take the regulator apart completely and make sure the spring is seated on the plunger.

Need to get it into my head that this is a regulator and not a pump.

How is pressure to the tank regulated?

This pressure is created by the crankcase, correct?

The pressure to the tank is not truly regulated. The check valve keeps the tank pressure relatively constant. It varies with all YS engines even of the same type. It is normally about 3 to 5 psi.
The regulator doesn't care about the tank pressure as long as it has enough to drive fuel through the system.

The regulator adjustment controls how much fuel is admitted to the engine as you transition from idle to high speed. If you open the reg screw, the plunger comes off its seat earlier in the transition which makes the transition RICHER. If you close it, it gets leaner.

The regulator has no effect on the top end and little effect on the idle unless your idle speed is quite high. The regulator normally comes into play at 2300 and above.

Thanks Dave..

What are they symptoms of a bad check valve? Say intermittent?

Every time I have checked it, it seemed OK and I have never seen fuel in that line either. I have changed everything but this at this point.

I know loss of pressure in the tank, but if the tank had pressure and was full and somehow fuel was allowed back to the engine. Would it get back to the crankcase?


Thanks for your help and valuable insight..

Usually the check valve either works or it doesn't. Take it off and blow through it then suck it back the other way. If it seals ok, I would say no problem. Take it apart and make sure there is no crud in it.

I doubt that you could ever get a back flow into the engine even with a bad check valve.

Well Dave found the fix..

Must be the o-ring on the high speed needle. If not then the fit between the high speed needle and carb is out of spec. Bit puzzled why this was not discovered when I returned it...

Was talking to another pilot at a LHS and he suggested putting a piece of fuel tubing over the needle and carb. I did, a piece about 3/4 inch long that would seal between the two.

Started fine, checked high end, tached at about 10600.

Set low end, funny thing here is now the low speed needle appears to be in about the right spot (several turns in instead of flush with card body).

Transition fine, maybe a little rich, but manageable.

Flew maybe half dozen flights yesterday, absolutely no problems whatsoever. Idle was great, almost did not want to quit.. Flat spins from altitude with idle to full speed recovery was all I could hope for.

I did not let this beat me, its running and running great. And the fix most likely the o ring, but for now I'm leaving it as is and going to enjoy it for awhile..