R100 Exhaust Rocker Arm Bluing

Discussion in 'Airheads' started by senatorperkins, Jun 14, 2012.

  1. senatorperkins

    senatorperkins Adventurer

    Joined:
    Jun 11, 2012
    Oddometer:
    40
    Location:
    SF Bay Area
    Hi guys, first post here.

    Just bought a 29k 1978 R100/7, and I was going through the mechanicals and fluids and came across this:

    [​IMG]

    This is the right side exhaust rocker arm, and none of the other arms show any similar signs. Push rods rotate freely and smoothly at TDC compression for both sides, and there doesn't seem to be anything wrong with the valve guide or the valve stem. The valve clearances were the same right and left, though the exhaust ports were about .18mm and .15mm is called for on r100 so I re-set to .15 after adjusting end play. No signs of trouble yet, but I'm wondering if this is bad news?

    Thanks,
    Ryan
    #1
  2. RecycledRS

    RecycledRS Along for the ride

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    They all look like that, part of the hardening process.
    #2
  3. ozmoses

    ozmoses Ride On

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    I wondered the same thing once about a bike I bought w/ no valve lash after riding it several hundred miles home ( brought zero tools as it was "ready to go x-country...). I was assured it was fine by a "guru" of sorts; no issues to date & 20k miles.
    #3
  4. wirewrkr

    wirewrkr the thread-killer

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    Not all.
    That process started in late 1976 (IIRC).
    #4
  5. ignatz72

    ignatz72 call me iggy

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    Not bad news now that you have it adjusted properly, but someone let it get (or set it) too tight at some point.
    #5
  6. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    That rocker looked like that before it was ever in a bike. They heat treat the tips to harden them.
    #6
  7. senatorperkins

    senatorperkins Adventurer

    Joined:
    Jun 11, 2012
    Oddometer:
    40
    Location:
    SF Bay Area
    Thanks, this is a relief. Strange that it's only this one arm with visible bluing, but I'll rest assured now.
    #7