Blackbird woes

Hi Guys

I have had a fun day in the garage today attempting to get to the bottom of
what is wrong with my lump.  Not cam chain tensioner, not clutch assembly.
Think highly likely big end on 4 has picked up and is giving a bit of piston
slap.  Took out clutch plates and ran without and has a listen with
stethoscope - noise high up and in vicinity of #4.  In the end took engine
out ready for a full strip.

I have had a look at my manual and also investigated the web.  It seems to
me that from 2001 onwards that the engine on the bird remained unchanged to
the end of production in 2007.  Can any of you confirm/give clarification of
this or describe modifications?  I have also had a look about for a second
hand unit.  Any suggestions as to how much I should look to pay and/or from
where one could be sourced?

Jonathan Rarity - do you still have billet sumps for the bird?  We discussed
this last year but I was distracted and didn't come back to you - sorry!  I
would be grateful if you would be so good as to give me a call on 07766 620
987.

Cheers
Phil Lovegrove