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yet another problem!

Discussion in 'Norton Commando Motorcycles (Classic)' started by Geoff, Apr 19, 2006.

  1. Geoff

    Geoff

    Joined:
    Aug 20, 2005
    I am having a right saga with my 850, I have had the head off 3 times now. I will describe the whole epic another time - head gaskets, stripped studs etc!!
    I fitted new inlet valve guide seals to the existing valve guides which are not worn, but within 200 miles or so these have failed, the top part has torn away in the form of a small ring. HAs anyone else had any experience of these? They seem vital as oil gets down the guides & burns when they are faulty
     
  2. Keith1069

    Keith1069

    Joined:
    Jan 10, 2005
    Sorry to hear about your head troubles.....I've been through all that, the stripped studs scene. It was only when I got Norman White to do a proper helicoil job on the three head studs and blew the engine so I had to replace the Steve Maney 750 aluminum barrels with CI 850 lookalikes that the problems stopped. On the seals, I had problems with replacements which had too large a diameter bore and leaked. I just checked my new seals and one is very tight on the stem, other not so. Without oil they are both very, very tight and I can imagine happening what happened to you. Did you oil them up first?
     
  3. Geoff

    Geoff

    Joined:
    Aug 20, 2005
    I had no problem fitting them but when I had to take head off again for stripped thread, both seals had torn in the form of a ring at the top. I am going to loosely assemble top end somehow & measure clearance from top of guide to bottom of spring retainer in case seal got crushed. Also it is possible that I compressed springs too far in fitting seal. More research follows!
     
  4. Keith1069

    Keith1069

    Joined:
    Jan 10, 2005
    You could be right and maybe forced the retainer onto the seal and sheared it against the top of the guide but you'd have to compress the retainer a long way to do that. It's the only logical explanation though. I just compress the spring enough to slide in the collets one at a time. Good luck.....I just wish I had a head to rebuild, currently at CHS for 4-1/2 months. he keeps promising!! Normally I do my own headwork but I heard such good stuff about their Serdi valve jobs that I thought I'd get it done professionally for a change and now with 21 deg weather promised this weekend I can only dream about riding. Hey ho.
     

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