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Dave Liquorice[_2_] · 24-10-2012, 09:04 AM posted to uk.rec.gardening

On Tue, 23 Oct 2012 16:49:53 -0700 (PDT), wrote:

It's a pretty damn well near impossible to pull start a diesel
without releasing the compression, spinning it up, dropping in the
compression and hoping the flywheel has enough inertia to take it
through compression and for it to fire.

Its funny when I hear people say that, I used to do it daily. I daresay
its true for car sized engines.

My little (300cc) single cylinder diesel genset is almost impossible to
pull through compression. It can be done but it's not very pleasant on
the fingers and more than two or three pulls hurts the arm. Because it's
so hard to pull it might not fire as it's not going fast enough and the
cylinder/block is cold. *Much* easier to operate the decompression
lever... Some engines have cunning automatic decompression mechanisiums.

By comparison a petrol engine has very little compression. Think about
the effort needed to half push in a bicycle pump with the end blocked and
the effort required to push it in to within the last inch of the end.

--
Cheers
Dave.