YS 91 problem
 

Hi.

I have a YS 91 (not more than 5 tanks of fuel trough it) in my UCD3D. The engine keeps quitting on me. When I trottle down to idle, it quits when I try to throttle up again. This only happens when the plane is airborne. On the ground, it works perfectly. I'm not familiar with YS engines, but the needles seems to be very sensitive...

Kan anybody give me their needle settings?


Lars

YS 91 problem
 

Hello Lars,

If you have the engine cowled, which I assume it is in the UCD, you might want to open up the cowl some to let the engine vent. This sounds like the engine is overheating in the air.


Azhar

YS 91 problem
 

No, it's not cowled. I wanted to wait for the engine to run in before putting the cowling on.

I'm not running the engine hard at all, just flying around at 1/3 speed, and sometimes pulling full throttle.

First it was difficult to get the engine to run at all. It seemed it would either run rich and quit, or run too lean... Maybe I've got a bad engine??

Lars

YS 91 problem
 

What fuel you using? How much nitro? Also which plug?

YS 91 problem
 

Lars,

Check your regulator screw and see whether it is flush with the housing. If it is screwed in too much, it might cause insufficient fuel to the carb.

Azhar

YS 91 problem
 

Sprink:
I'm using a Norwegian fuel. 15% nitro and 15% Aerosynth Competition oil. This is the same fuel that I use on my helicopters (OS 91 C-Spec), and I've used this fuel on OS 91 FS also.
The glow plug is a OS F plug.

Azhar:
I will check the regulator screw.

Thanks guys!!


Lars


ps. the engine is mounted inverted, but I've heard that this is no problem for the YS.

YS 91 problem
 

Lars,

Since you are using 15%, the needle adjustment can get a little exciting, even frustrating. So be patient. The YSs are designed around the 20/20 fuel, but I understand that nitro is expensive in your neck of the wood. Good luck.

Azhar

YS 91 problem
 

Lars,
Also 15% oil is a little slim, the YS four strokes really like 20-22% synthetic oil. What prop are you turning? I really like the apc15x7 for this engine, good pull and throttle responsive.
DKjens