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Help ZXR250C - Rebuild V2

Discussion in 'Kawasaki 250cc In-line 4's' started by DanoHosko, Oct 21, 2022.

  1. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    New rods are USD 51 from Impex but Aus customers have had problems getting things shipped amongst others. Megazip will have them too.
     
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  2. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Sorry guys I didn't see these replies!
    I'll keep ya posted with the progress, I'll be a bit slower during the week..

    Yeah Impex and Megazip both seem to have a load of parts at the moment, postage is slow but that's fine I'm not in a massive rush ;)

    I'll get the details off the crank and hopefully my mates micrometer this week

    Here's my journel #3, I can't get my nails to catch on it at all but it does look a little rough up close...

    _20221023_164542.JPG

    And the inner of the rod
    _20221024_212239.JPG

    _20221024_212326.JPG
     
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    Last edited: Oct 24, 2022
  3. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Those look dead I'm afraid.

    Best bet find another crank.
     
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  4. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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  5. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Yeah gross prices :(

    Presumably with a new crank means replace all the bearings and conrods to match a new crank?

    $$$$
     
  6. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Lots of buying bearings, measuring and swapping bearing shells around, for both the main journals and rod journals.

    Basically measure the new crank main journals, bolt the cases together empty and measure all the respective holes and calculate bearing sizes. After that you have to assemble with bearings and check with plastigauge to confirm clearances. Very time consuming job but necessary for accuracy - these clearances are critical for good oil flow and to ensure nothing seizes. It's the heart of the engine after all.

    If you've never done it before it can be a daunting task, I've only done it a handful of times and not on my own either, and not on an inline 4 (mostly on Ducati v-twins)

    I think your cheapest and easiest option would be to find another donor engine, but that comes with its own risks, if buying an engine on its own (most of them are out of a bike for a reason). Best way to do it is to find someone wrecking a ZXR that's still assembled and runs, and is being sold for parts for other reasons.

    Even then these things are all old and will need attention in one way or another.
     
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  7. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Yep, what @Linkin said.
     
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  8. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    You wont know what you need until you get some measurements. I think that crank would clean up ok, but the size will be the deciding factor. The rod can be closed and re honed to the right size, but again you need to measure first before buying bits.
     
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  9. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    While what @Murdo says is correct the difficulty these days is finding the engineering shops that still have the skill, expertise and equipment to do the work... They are getting few and far between these days. When I was looking to get the SRX bored I had a hell of a job finding someone with the gear that could (would) bore a cylinder that small. The guy I found was in his 80's and had a full workshop of old machines that ranged from small motorcycle engines to big Cat V16's but 90% of it sat idle for too long. Last I heard he sold most of it for scrap and moved to the Central Coast to go fishing...
    Maybe we need to start a Thread identifying the engineering shops around that provide suitable services for all of us that still tinker with the old stuff and may need some of the specialised services...
     
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  10. jmw76

    jmw76 Well-Known Member

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    A great idea Andy. You are right. It is getting increasing difficult to find good machine shop help.
     
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  11. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    There's a joint in Mackay where I live, (MCS Automotive) that reckon they can measure the crank and they do linishing if required, so I'm thinking yeet it over to them get them to measure the journal, if it's got enough meat left on it then get it linished.

    Conrod 3 has got some discolouration (i'll try and get a photo) in comparison to 2&4, so assuming it has gotten a bit on the hot side..

    At the moment the options really are:
    - Use existing crankshaft, replace all bearings and maybe conrod 3 (cheapest and depends on the crank)
    - Buy a new crank and bearings (mucho $$$$)
    - Donor engine (risky)
    - Donor bike (potentially still gonna be $$$$)
    - Cut my losses :)()

    I'm a little on the sentimental side, so i would prefer to keep the old girl running, plus with all the other work I have done already I know that there's very little left that can go wrong (lol), and it would be a shame to send an engine to the scrap heap if it could be salvaged, within reason.
     
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  12. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    If you rebuild the engine then you know you have done everything; at that point it becomes a keeper. See how it looks after the machine shop cleans it up. Donor bikes and engines pop up and the savvy buyers on the forum usually pay $500 or less.
     
  13. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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  14. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Would the journal need crack testing?
     
  15. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    I'll bear them in mind, not sure how helpful my local place are actually going to be after speaking on the phone...
     
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  16. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    I very much doubt it. They are a strong crank for their size and you only burnt a bearing, not like it broke the rod.
     
  17. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Yeah I suspected as much, the engine rebuilders were laying it on thick over the phone saying I would need to crack test etc, to be honest it's almost like they didn't want to do the work...

    It is Mackay though so maybe 'crack test' means something else here... ;)
     
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  18. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Easy sleazy....


    On a side note, is there supposed to be silicone gasket around the casing joins?

    DSC_4073.JPG DSC_4074.JPG
     
  19. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Cases should be sealed with Kawasaki bond, probably number 1215 or similar Threebond product
     
  20. DanoHosko

    DanoHosko Well-Known Member Premium Member

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    Ah right on! Guessing thats right then, I wasn't sure if it was from factory or if someones been in there before haha
     

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