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DF25 Timing Mark 90 deg off on crank

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  • DF25 Timing Mark 90 deg off on crank

    Well fellas, and possibly ladies,

    Got an issue I've never ran into, so I figured this is the perfect opportunity to join a forum!! Please bear with me, this may take a minute to explain.
    . A few months ago had a customer complain about loss of power in his 1999 DF25 four stroke. Next day he tells me it came to an abrupt stop and wont do anything. Low and behold, it skipped timing and bent every exhaust valve.
    . Following the suzuki service manual, I replaced the exhaust valves and related parts, as well as the timing chain and cam sprocket. Unfortunately the tensiontension longer available, but after some testing this one seems to be working fine.
    . Now for the fun part. I aligned the timing Mark's as the manual described, but found the top of piston 1 was hitting the exhaust valve again while turning the engine to set the valves on cylinder 2. Also found the tip dead center Mark's on the camshaft were also not aligning when their cylinders were at TDC. Long story short, this entire problem was corrected when I rotated the crank 90 degrees. Everything lined up as it should ( other than the crank mark) I have compression and zero piston to valve interference.
    Got the engine back together tonight. She started up and soundedpretty good. Went to start her a second time and she damn near ripped my arm out of socket with the pull cord. I've already determined that the pull cord mechanism is fine and has zero issues. So, any ideas?Resized_20201026_192256.jpeg

  • #2
    And, I'm fully aware that what I just described as moving timing Mark's off 90 degrees sounds like something from spaceballs........but believe me, the engine would not stop interfering with the valves had I left the Mark's aligned. Had it together and apart atleast 5 times......

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    • #3
      Did you ever figure out what happened with 90 off TDC? I was just curious

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      • #4
        The starter cord "pulling back" is a sign of timing being wrong, it fires way too early and stops dead, or even worse, backwards for a second, I suggest you have done something terribly wrong, especially if you have been playing with the timing chain.

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        • #5
          I'll be tearing it back down next week. I'll send some photos.

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          • #6
            Did you first establish why it bent the valves, or are you assuming it was from the loose chain and tensioner, it sounds like it sheered the key on the crank or the locating pin on the cam the first time, If it sheered the key on the flywheel it would only effect ignition timing. If the crank and cam locating keys are fine, you are setting the camshaft timing up wrong.

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