help w/ electrical stuff and valve timing (1975 kz400)

Discussion in 'Motorbike Technical Discussion' started by jseely13, Aug 11, 2004.

  1. jseely13

    jseely13 Guest

    i got a 75 kz400 a while back that wasn't running, and spent the last
    4 months or so tearing it apart and putting it back together. i got
    it running about two weeks ago, and took it out for a couple of
    illegal spins around the block before i noticed that my (new) battery
    wasn't recharging when it was running. i consulted my shop manual,
    and it says i need to look into the regulator, rectifier, battery, or

    the battery is good, and the recifier checked out. the field coil
    was replaced by the prev owner w/ a new used part (he was dealing w/
    the same problem), and i replaced the old regulator w/ a new used part
    b/c the old one had had the cover removed and had rusted out. so,
    that leaves me feeling it's probably the stator, but i'm not sure. (i
    think) continuity was good between the 3 connections.

    i found a post on the net about a guy w/ a cb700 having the same
    problem as me, and he said he checked continuity on the 3 wye
    connections and it was good, but that he was only seeing 4 volts or so
    from each wire when it was running. i decided to try to do some
    testing on the part tonight to see if i could see the same behavior
    and know i needed a new stator.

    the first thing i did was do the tests the manual suggested though.
    i disconnected the 6 pin on the left side of the frame (under the
    tank) and the 9 pin by the light to remove load from the dynamo. i
    disconnected the recifier white plug and hooked it to my + lead on the
    multimeter. i grounded the -. then i unplugged the green and brown
    from the regulator and connected them together directly. doing so, i
    noticed that i'd had those wires reversed by accident (the new
    regulator i got was from a different year bike, and the color coding
    was different tho the letters on the pins are the same as my old one).
    i started the bike up and didn't see low voltage that the manual says
    indicates a bad dynamo, but rather want to say i saw 18-25V (not sure
    exactly, but it was higher than my reading of 13-14 on the battery
    [note that my idle is high b/c i think my carbs are due for a
    rebuild]). is this too high? anyway, i proceeded to unplug the 3
    wire yellow 4 pin for the stator and tried to check for voltage coming
    off of that, but got no reading w/ the - grounded or touching another
    of the 3 pins. i think i had voltage coming through though because i
    saw some spark a couple of times while doing the testing.

    so if you've suffered through my verbose description, i bet you're
    wondering where valve timing works into this. well, the prev owner
    was over a week ago and he said the valves were tapping when the bike
    was running, so he suggested we adjust them. he didn't remember how
    to do it right, and we didn't find it in the manual, so we removed the
    covers and unbolted the adjuster screws and adjusted them w/ the bike
    running until the tapping was minimized. later i found the proper
    procedure in the manual, and adjusted them "correctly" (going to tdc
    on one side, adjusting to .10 mm gap, then rotating the crank 1 turn
    to tdc and adjusting the other side). well, while the bike was
    running during the electrical tests i'd noticed that one muffler was
    much hotter and pushing more air than the other. the cool one was
    burping flame occasionally as well. after about 15 min, i glanced at
    the hot muffler and noticed the pipe near the engine had an orange
    glow to it. so i turned off the lights, and sure enough the pipe was
    glowing orange... i killed the engine at that point...

    so... i'm left with a couple of questions that i hope you ppl can
    help w/...

    1) could the regulator green/brown reversed have been the source of
    my discharging problem?
    2) is there a proper way to check the stator wires for voltage?
    3) how do i unbork my valve timings so i don't destroy my
    engine/muffler? i noted in the manual that it said to always keep
    the valve adjustment screw punch marks on the side of the +/-. i'm
    almost positive we rotated them multiple times when we were messing w/
    the timing initially. for the hot pipe, should intake/exhaust go + or
    -? for the cold pipe that's belching fire on occasion, should it go
    +/- , or is that sommething else (perhaps carbs)?

    i love this bike and hope i haven't done it irreperable damage. i'd
    like to track the electrical problem more (perhaps it wasn't running
    long enough to notice a discharge, but i don't want to destroy it...
    the bat is showing 13+ volts atm). the weather here has been great
    and everyone who has a motorcycle has been out riding it, and i'd love
    to be out w/ them, but there's work to be done obviously. if you can
    provide assistance, it's much appriciated...


    -- john
    jseely13, Aug 11, 2004
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  2. jseely13

    jseely13 Guest

    I noticed today that oil seems to be leaking into the hot exhaust pipe
    when it runs.

    I'm debating whether or not to try adjusting the rockerarm screw '-' a
    couple of turns, or if I should just take off the breather cover and
    reset the camshaft and rocker arms.

    No idea on the cool running pipe. Maybe the intake valve is off?

    -- John

    jseely13, Aug 11, 2004
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  3. jseely13

    jseely13 Guest

    I noticed today that oil seems to be leaking into the hot exhaust pipe
    when it runs.

    I'm debating whether or not to try adjusting the rockerarm screw '-' a
    couple of turns, or if I should just take off the breather cover and
    reset the camshaft and rocker arms.

    No idea on the cool running pipe. Maybe the intake valve is off?

    -- John

    jseely13, Aug 11, 2004
  4. Do what?
    The Older Gentleman, Aug 11, 2004
  5. jseely13

    jseely13 Guest

    If I remove the breather cover, the camshaft has a gear w/ timing
    marks on it. So you put the bike at TDC, put the camshaft back in so
    a notch mark on the right side is pointing directly up, then move the
    gear according to the timing marks, rotate the crank until the gear
    bolt holes match back up w/ the shaft and reattach the gear and shaft.
    Something along those lines, I was looking in the manual at it again
    last night.

    I donno. My left side is running too hot, and the right side too
    cold. Spark plug conditions confirm that. I guess the side running
    cold is probably my carbs, and I've got a new set on the way. The
    left side m/b is running wrong b/c of carbs too (too lean?), but the
    glowing exhaust pipe and oil makes me suspect that exhaust valve is

    Last night I tried adjusting the rocker arm screw number of turns +,
    but it made no visible diff to the position of the valve. I also
    tried adjusting the screw on my carbs that controls syncro way in one
    direction and then way in the other direction, but the hot side
    continued to pump out a lot of hot air and the cool side put out a
    little bit of relatively cool air.

    If the hot/cold issue could be caused soley by the carbs, m/b I'll
    wait on cracking the engine open until I get the new ones. If the hot
    pipe is almost positively the exhaust valve not seating closed, then I
    just need to open it up and take a look I guess.

    To be honest I have no clue what I need to do, and seem to be venting
    to usenet...

    -- John
    jseely13, Aug 12, 2004
  6. Well, yes, but the cam timing won't have anything to do with your
    problem, so I'd leave it well alone.
    The Older Gentleman, Aug 12, 2004
  7. jseely13

    jseely13 Guest

    I would've thought it related b/c cam timing moves rockers which move
    valves... But I am new to all of this...

    Where do you suggest I look to solve it? I just ran it for 30-60 sec
    today to test the new tach I got. Right pipe was a little warm. Left
    pipe was really hot. Do you think it's valves? Carbs?

    If valves, should I just remove the breather cover and see if it's
    seating? If not, then...?

    tx for advice...

    -- John
    jseely13, Aug 13, 2004
  8. well, yes, it does, but it doesn't just go out of time unless something
    catastrophic happens to the engine.

    Carbs, sounds like. One may be running lean. Could be a burned out valve
    - check the clearances - but my money is on carbs. Actually,
    double-check the clearances. Early Z400s had an odd eccentric rocker
    shaft system, I think, and it's possible the clearances are badly set.

    You can't check for seating like that. You really need to remove the
    cylinder head and I strongly recommend you don't.
    The Older Gentleman, Aug 13, 2004
  9. jseely13

    jseely13 Guest

    ah, gotcha...
    ok, i've got carbs in the mail, so i'll just be patient i guess... i
    can redo the clearance. could running lean make it so hot that the
    pipe turns orange?
    well, if good carbs don't fix it, i'm guessing this is what i'll have
    to do. i hope it's the carbs tho. i worry that when we adjusted the
    valves while it was running we messed up that exhaust valve and the
    seal has burnt out, or the stem warped, or something.

    thanks much for your advice/help,

    -- john
    jseely13, Aug 14, 2004
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