Hi Keith,
It sounds to me,speaking as someone who has driven Herald 1200s for 16 years.
like you may have either too hot or too long a spark plug fitted to your
engine.
Did you know that the difference between the temperature of the spark and the
melting point of the aluminium alloy from which your piston is made is approx
ten degrees celsius?
Bearing in mind what you sais about exactly where the damage occured to your
pistons,this sounds like the place to start looking!
The plugs you should use are Champion L87Y or equivalent.
But be sure they really are equivalent because I don't always trust what I
read. Since you are in the UK,I suggest you telephone John Kipping on
01203-645333
(00-44-1203-645333 from USA)
Talk to him,he can give you all the advice you need,and supply all the parts
you need for your engine rebuild.
It's good to see another British Herald owner on the list,and if you are not
yet a member of the TSSC.may I suggest you join?
Good Luck
Leon F Guyot
Triumph Sports Six Club International Liaison Secretary
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