cylinder head ID - commando 1970

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Biker-man

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Aug 26, 2005
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I am looking for info to ID the correct head for a 1970 roadster.

I found the info below - Is this accurate ??? Where can good info on this be found?

TKS!!!!
 
info found

the intake ports it will tell you what year.

28mm up to 1970
30mm 1971 1972
32mm usually they have a C stamped on the top for Combat, higher compression and 32mm intake ports
850's have RH 4 or RH 10 over the right exaust rocker box, 4= 32mm 10= 30mm
 
That's interesting, I wonder what year the 28mm head was from, and if it will work on a 70???
 
Tks for the link - I had a look, great info source!

The site doesn't refer to the 28mm port head, so I'am still unsure about putting this head on my 70???
 
My 71 Roadster has 28 mm ports.

Who knows if that's the original head though :roll:

Debby
 
Port diameter

Norton twin port size is 30 or 32 mm measured at the intake manifold. Some heads neck down to 28 mm after the intake manifold connection.
 
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