DrV

My Feedback: (2)

Hi, I was wondering if tank placement will make a difference on idle. My YS-91 is mounted inverted and I cannot adjust the idle. Either it is too rich or too lean. The tank is about an inch or more above the carb when the airplane is upright. Is this too high? Should I lower the midline of the tank in line with the high speed needle valve? I know this is true for 2 strokes but I'm not sure if this applies to pumped engines.

Thanks

Mike

Dave Shadel

The tank placement has no effect on a YS. Something is wrong with the engine, or with the adjustments.

You didn't mention fuel, plug or prop. What are you using?

DrV

My Feedback: (2)

Thanks for the reply

I use YS 20/20 fuel, 13x10 prop APC, OS Type F plug. No matter how I adjust the pump, the bleed valve or the high end, it either quits on landing because it is too lean or too rich( loads up). I have given up on it, I just run full throtle at all times, then I just land dead stick almost every time. If it is not dead stick then by the time I turn it around and bring it back it loads up and quits. It has 3 gallons of fuel throgh it so far but since day one it does not run well. I have had motiple people look at it, no one seems to be able to adjust it.

Thanks

Mike

Dave Shadel

Have you checked the valve adjustment? VERY important to the idle.

Should be .003" on both valves.

DrV

My Feedback: (2)

No I have not. That may be the trick. Thank you. Where do I get a shim that thin? Would the OS valve adjustment shims work?

Dave Shadel

A crisp new dollar bill works just fine.

DrV

My Feedback: (2)

Hi Dave,

As a follow up, I Adjusted the rocker arms as you recommended which improved the low end but the engine loads up. If I have it running well before I take off, it will always load up prior to touch down or die after I landed. I have tried to start it up again right after landing and it loads up at the low end. Even trying to adjust the air bleed and the regulator to a point where it is slightly lean, it still loads up. I also changed the plug from OS F to YS plug. Still dong the same thing. Do I need to change the diaphragm or the plunger? The engine is relatively new and has been doing this since day one. It runs flawlessly on a stand but once inverted on the airplane it has never ran well. What are my options at this point and since it runs well on a stand is it even worth sending it in?

Thanks

Dave Shadel

As stated here before, the YS and OS plugs are the same, both made by OS.

I would try some Cool Power 30% heli fuel with the low viscosity oil. It may solve the problem, but be prepared to re-adjust the engine accordingly. It's cooling off and dying due to lack of heat at the plug while inverted. The additional nitro will help.

DrV

My Feedback: (2)

Thanks, I'll try cool power 30%.

I was also thinking of adding a glow driver. Would this work? or is it recommended?

Dave Shadel

Try the fuel first. If that doesn't do it, the glow driver will.