engine pinking causes?

pc recently crashed lost all previous newsgroup chains...

this concerns a new engine in a 1974 bmw R75/6 engine
just put a new engine in and it makes the same rattle/ping..

uses leaded 4star fuel of leaded..

all settings and valve clearnce checked and rechecked and are ok..

could this be the normal "pinking" and would it cause it to do this from
start up when engine is not under load?

 

"Pinking" (UK english) or "Pinging" (US English) usually
refers to detonation of fuel in the cylinder. It's different from the
usual clatter of older boxer twins.
I had an R60/6, and adjusted tappet clearances too many times,
trying to get rid of the noise. Finally learned to live with it, and
rode a lot of trouble-free miles.

 

pc recently crashed lost all previous newsgroup chains...

I am sure you checked the timing.....but you may have to retard it a
degree or two if you really want to get rid of it...

Fwed

 

Silly question, but it isn't running a higher compression ratio than it
shouild, is it? Old airhead boxers can have a the CR altered by metal
gaskets (popular mod is to lower the CR when travelling round the world,
to allow the thing to use low quality fuel) and I was just wondering if
someone had gone the other way or skimmed the heads.

The things have really primitive head design, and old ones used to need
premium high-octane fuel.