Converting lawn mower to manual throttle?

 I have a cheap MTD mower with a 5hp B&S engine.  The "automatic"
throttle lost a spring and the plastic piece that appears to control the
engine speed (the vertical piece in this pic:
http://www.kichline.com/chuck/fixit/mowers/bs4hpspring.jpg )
is broken so I converted it to a manual throttle cable.  I connected the
cable to the piece that is connected to the plastic piece in the above
pic via a rod with a loop in it.  (Hopefully the pic and description
make sense).
The thing is that if I'm sitting still the cable controls the RPMs as
expected but as I move the mower around RPMs fluctuate even if I'm not
cutting anything.  I except the RPMs to drop when there's a load from
cutting but it seems random and will surge and drop.

Any thoughts?  Is there something else that controls engine speed that I
haven't found on this engine?

thanks in advance!

 stoneattic wrote:

It looks to me like the vertical piece is the govenor, that adjusts the throttle
according to load. Missing that, the speed will be very unstable.

 

On Tue, 09 Jun 2009 23:06:17 -0400, stoneattic


I'm late but you still need the automatic part, even with a manual
throttle.   They all have it. Otherwise it will stall quicker than you
can ajust the throttle.