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Interesting things during my first valve adjustment

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    Interesting things during my first valve adjustment

    I've never adjusted valves on a bike before. I'd done shims on my Volvo once and that sucked, and I'd already turbocharged the car and swapped engines before, so I know what sucking is.

    So since my bike ate another igniter I decided that it was time to check my valves. I've ridden the bike less than 1,000 miles since buying it with 24,000, but figured I may as well since who knows how it was treated before.

    Turns out they were all too tight. I can't say by how much other than to say my .05mm feeler guage wouldn't fit through any of them at dead cold. So I adjusted them out to a slight drag at .076mm, and put it back together.

    A note about oil: I use Amsoil full synthetic in my bike and a full day after shutting it off it was still all over the cams and valves up top, so I'm impressed with the stickiness. I'd never seen this happen after opening up any of my other dino-oiled OHC engines.

    So I adjusted all the valves, put new transistors into the igniter, and cranked it over. WEIRD STUFF: It sounds totally different now. I'm not talking about valve noise. I'm talking exhaust sounds. It makes popping type sounds, is deeper sounding, and overall sounds quite different while cranking.

    On the road it sounds deeper, less high and roary (Kerker exhaust) than before. I'm willing to bet the valves had close to zero clearance before. Maybe this caused some weirdness with early open/late close.

    Either way the bike runs differently now. It even pulls differently. I swear from the shakedown runs it has noticeably more midrange torque than before. I haven't wrung it out yet, but it feels stronger now. Very strange.

    Oh, and the hard starting is still there. Damnit.

    #2
    Ok... apparently not interesting enough.

    Is .076mm an ok clearance for a 16 valve 750 or not?

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      #3
      Is .076mm an ok clearance for a 16 valve 750 or not?
      I have an 1100E, so I cannot comment directly on your 750. BUT. Pretty much all of the 16 valve stuff interchanges, including heads and cams. So I would guess the clearances do, as well. Your 0.076mm = 0.003". The manual sez 0.003-0.005" lash for my 1100. So I would say you are on the tight side. I set all my valves to 0.005" when I did them the other day...

      Mark

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        #4
        If the valves are set tighter the effect is to increase duration, increase lift, and decrease overlap. This is similar to putting in a hotter cam, so yes, increasing the lash has the opostite effect and you get more midrange. This is valid within a certain range, of course.

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