YS 120 question

[Ron Van Putte]

It sounds like the regulator valve is sticking open.  Remove the 
regulator cover and carefully disassemble the regulator assembly.  I'll 
bet you'll find deposits on the stem of the brass piston, which 
sometimes causes the valve to stick open.  Clean the stem and 
reassemble the regulator assembly.  If that doesn't cure the problem, 
I'll send double your money back.

Ron Van Putte

On Oct 3, 2005, at 11:02 AM, Anthony Abdullah wrote:

> I had a rare opportunity to fly my pattern plane this weekend and 
> noticed that my good ol trusty YS120-FZ seemed a little down on power. 
> It didn't act lean or rich and after the flight the fuel system still 
> had plenty of pressure so I don't have an air leak. The valves were 
> recently adjusted and everything mechanical seems to be in good 
> working order.
>  
> I checked the needle settings and ran it up for another flight. On the 
> second flight I noticed that my usual light smoke trail only showed up 
> at certain times. I flew across inverted and had a good healthy smoke 
> trail (inverted mounted engine when viewed upright). Uplines were 
> pretty good, but straight and level flight left no smoke trail.
>  
> I landed and fueled up again.
>  
> On the third flight, while my helper was holding up the plane and 
> approaching the runway I noticed a relatively large amount of raw fuel 
> blowing out of what looks like the carb area (hard to tell with the 
> prop spinning that fast) when I advanced the throttle. Mind you, 
> nothing has been changed on the engine in quite a while, same prop, 
> same type of plug, same header, same carb, etc.
>  
> Question:
> does anyone have any idea where the raw fuel might be coming from. I 
> checked the head bolts and they are tight. If it is spraying out of 
> the carb why is it doing that and how can I fix it? Could that curved 
> down tube be leaking fuel at one of the o-rings? Once again, I am not 
> losing any air pressure from the fuel system and the engine is still 
> very reliable except maybe needing a slightly higher than normal idle 
> setting. Other than the raw fuel and being slightly down in power, it 
> still starts and purrs like a kitten.
>  
> Thanks in advance for any help you can provide.
> Anthony
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