[NSRCA-discussion] YS 140 FZ: loads up and dies 2500 - 4500 rpm

[Bob Kane]

You have seen some other answers, I forgot about the valve cover fix. It is easy and if it fixes your issue, great.  The entire crankcase of the YS engine series is used for the supercharging process so a leak in any gasket can cause problems.  Otherwise, a rebuild, including new bearings (at least the rear, both if you don't know the history of the engine), piston, ring, and gaskets.

Come to think of it, another seal that can can cause issues is the throttle barrel seal. If it is cut or torn you will have problems also.  Be careful pulling the throttle barrel out, you can cut the seal on the machines edges.

 Bob Kane
getterflash at yahoo.com




________________________________
From: Paul Horan <paul.horan at sbcglobal.net>
To: Bob Kane <getterflash at yahoo.com>
Sent: Monday, February 2, 2009 3:08:57 PM
Subject: Re: [NSRCA-discussion] YS 140 FZ: loads up and dies 2500 - 4500 rpm


Bob,
   I'm not sure of the time on the engine, it's used.  But this only happens on the low end just above idle.  Does that fit with piston rock ?
Paul

--- On Mon, 2/2/09, Bob Kane <getterflash at yahoo.com> wrote:

From: Bob Kane <getterflash at yahoo.com>
Subject: Re: [NSRCA-discussion] YS 140 FZ: loads up and dies 2500 - 4500 rpm
To: paul.horan at sbcglobal.net
Date: Monday, February 2, 2009, 1:56 PM


 
How much time on the engine?  Surging on these engines was a sign of piston rock, the fix was the DZ piston and a new ring (or drilling the gas holes from the top of the piston to the back of the ring groove). This was more of an issue on the L series, but your problem sounds the same form your description.

 Bob Kane
getterflash at yahoo.com 




________________________________
 From: Paul Horan <paul.horan at sbcglobal.net>
To: General pattern discussion <nsrca-discussion at lists.nsrca.org>
Sent: Monday, February 2, 2009 2:18:27 PM
Subject: [NSRCA-discussion] YS 140 FZ: loads up and dies 2500 - 4500 rpm


    The problem is a YS 140 FZ that runs fine at idle and 40 to 100% throttle but loads up around 2500 - 4500 rpm.  This is especially nasty since that is the rpm range for a smooth takeoff,  once it goes to full throttle the engine does not develop full power (about 40% power) and dies.   Plenty of smoke trail so it is not going lean.   
   Another symptom is on the ground running  2500 - 4500 rpm the rpm is not steady. 
Help,
Paul
NSRCA 3606  


      
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