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Help Crankshaft removal

Discussion in 'Yamaha 250cc In-Line 4's' started by stocky, Oct 19, 2013.

  1. stocky

    stocky New Member

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    I'm trying to split my engine case and remove the crankshaft, and I think I have one crankcase bolt left behind the magneto housing. I can't get to it as I can't find any way of cracking the 14mm bolt on that end of the crankshaft. Any ideas how I do it?
     
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  2. dontz125

    dontz125 Active Member

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    Impact wrench.
     
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  3. driftwood

    driftwood Active Member

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    It looks like a 16mm bolt will pull the maggy off - fine pitch?
     
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  4. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Are the rods and pistons still attached? Blocks of wood under the pistons on either side, or jammed between the crank webs and cases (with pistons and rods removed) and something or someone to hold the engine down while you lean on the bolt with a cheater bar.

    If the engine was still assembled I'd just zap the bolt with an impact
     
  5. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Here's how I did it, you can use the filter strap wrench to hold the flywheel to crack the nut with an big impact driver 1/2" drive, the one with the socket connector, also use a 6 sided (impact) socket if you have one

    https://www.2fiftycc.com/index.php?threads/tool-of-the-week.10190/page-3#post-118274

    Now it's M16 1.5mm pitch for the 3LN flywheel removal bolt, the 2KR is a fine pitch @neoncrypnid knows all about the trials and tribulations of getting a 2KR flywheel off because of the bolt which was basically unobtanium - 16mm x 1.25mm pitch - bugger difficult bolt to locate anywhere in the world

    hope this helps
     
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  6. driftwood

    driftwood Active Member

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    Wonder if using the impact driver jammed maggy on tighter, plus crank aint built for lateral impact? Couldn't budge the 16mm with a breaker bar & heat gun on boss working alone, until a 2nd pair of hands was recruited. Did another with just the breaker on the 14mm, and the maggy then popped easily.
     
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  7. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    FWIW - when I tried with 1m long bar on socket, nothing budged, then I borrowed the impact and ZOOM off the retaining bolt came, same for the bolt screwed in, to remove the flwheel

    They were done up to stay put at the factory, that much is certain!
     
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  8. driftwood

    driftwood Active Member

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    Wondering if there's any main seals 931-01281-57 available? Not leaking, but maybe 5deg of angular wiggle.
     
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Most likely a standard size so should be able to get one at bearing shop. Check dimensions on the old seal.
     
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