Allen Nugent wrote:
> I understood that you should red-line it a bit, under little or no
load, to
> establish the running limits. The conn rods stretch at the top of the
> stroke, and the amount of stretch depends on their deceleration.
Therefore,
> if you avoid high revs during run-in, the ridge at the top of your
cylinders
> will extend too far down, and you will risk breaking a ring if you
red-line
> it sometime after it is run in.
There is an element of truth in this, but I cannot vouch for its
veracity at run-in time. It is important though at many stages in
an engines lifetime to spin it to the redline.
I once overrevved (to ca 10,000 rpm) my Moto Guzzi. The bike had
60,000+ hard-ridden miles (lots of time spent at the redline of 8200)
but on this one occasion, *ping*. The result was that I broke the
land between the rings on one piston, presumably because I stretched
the conrods so much that the rings could not "sqeeze" into the area
where they had previously never travelled. Something had to give, and
in my case it was the piston, not the rings. I drove another 2000
miles with the piston like this, albeit slowly!
Lesson learnt here was to use Carillo conrods and forged pistons!
The Guzzi now has 162,000 miles, same pistons and rods.
Shane Ingate in San Diego
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