4-stroke problem

[jed241 at msn.com]

George,

I had a similar problem after about 10 flight. I pulled the regulator body 
off and inspected every thing very carefully. The only thing I found was 
flashing on the silcon seal on the end of the plunger. When I applied 
pressure to the spring I could see that the flashing was making contact with 
the regulator body.

I carefully trimmed the flashing off and put it back together. I had to lean 
it a bit more, but haven't touched it in about 20 flights. Very reliable now 
and hasn't failed to start.

I have it in a 5lb 7oz Aresti and it has no problem rocketing the plane 
around.

Hope this helps...

See ya,

Larry


----- Original Message ----- 
From: "george kennie" <geobet at gis.net>
To: <discussion at nsrca.org>
Sent: Friday, June 13, 2003 10:25 AM
Subject: 4-stroke problem


> I'm having a difficult time with a brand new YS-63. Running Powermaster
> YS-Blend 20/20, 12X6 APC, OS-F. It starts O.K., but when you advance the
> throttle to full it takes about 20 seconds to slowly build up to max rpm
> and then if you retard the throttle to anything below 8-9k rpm and leave
> it there within approx. 5 seconds it will start to "splat, splat, splat"
> and then abruptly quits, or if you try to advance the throttle it will
> do the same thing and quit.After it quits, fuel will well up in the carb
> bowl and overflow like the plunger in the regulator is not seating,
> however I have inspected the regulator and the plunger silicon valve and
> everything appears O.K.  I can even blow through the feed aperture in
> the regulator and no air will go through it until I push on the plunger.
> The are no burrs or any stickiness impeding the smooth operation of the
> plunger and yet after a short run of a few seconds it acts like the
> plunger is sticking in the depressed position.I've tried turning the
> regulator screw as much as a couple of turns in as well as out and
> nothing seems to help.
> Anybody know why the regulator seems to be allowing fuel passage when
> the engine isn't running? I compared the regulator spring length to a
> brand new unit and it has the same length. There are no holes in the
> diaphragm and the silicone valve seat appears smooth and does seat and
> seal manually.
> It will Idle, but as I recall that's a completely separate fuel
> circuit.Is there something in the high speed carburetor circuit that
> could be malfunctioning in such a way that pressure is getting back to
> the top side of the plunger and holding it in the open position?
> What do I do here, guys? Eric? Anyone?
> Thanks guys,
> Desperate Georgie
>
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