[NSRCA-discussion] YS 160 question

[Bob Lavey]

Greetings,

I have a question about the YS 160 in my Abbra.  I've got about two dozen
flights on the plane/engine, since I bought it (used).  It's run great up
until yesterday, when I barely got one flight on it.  I got as far as the
square loop in the intermediate sequence (yeah, first maneuver), and it
sputtered and choked at the top of the vertical line and across the inverted
horizontal top line.  I rolled it over, and it seemed okay, so I tried
again.  Same result.  I got it back down without incident and ran the engine
on the bench, and it was lean in the mid-range and top end.  It got very hot
during the short time I ran it on the bench, and it seemed to get leaner the
longer it ran.  I tried the high-end needle and small rich adjustment on the
pump, but neither helped.  It ran great last weekend, so I don't think it
was a mixture setting.  I then started checking the fuel lines and vent
lines, but they seemed okay.  Then I noticed the check valve on the head
would rotate.  The one on my other 160 doesn't rotate, and since I thought
those were a press-fit, it doesn't seem like it ought to rotate.  I gave it
a gentle tug, and it didn't come out of the head, but it rotates pretty
freely.

Is that a bad thing?  Or should I continue looking for an air leak in other
places?  Any other suggestions?

Does that check valve just pull off, and I can I replace it by just pushing
another one on?  Can it be that easy? :)

Thanks!
Bob

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