848 Evo Big End Failure.

Discussion in 'Builds & Projects' started by Paul55, Jul 7, 2026 at 11:11 AM.

  1. My track bike went bang on the sighting lap at Brands a couple of weeks ago.
    Fortunately I noticed an odd noise as I queued in pit lane that got louder as the sighting lap progressed, so switched off and free-wheeled back to the pits.

    Front cylinder big end shells had melted. Looks like I need a replacement crank, con rods and maybe pistons.

    Due to cost, the alternative may be part out the bike, but that feels like putting down the family pet :broken_heart:

    Sympathy, optimism, help and cheap parts gratefully received :sob:

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  2. you know my views on this.... part it out. chucking newer/differnt bits into the old casings might exacerbate wear on the 'legacy' bits
    youve had a great run with this so time to let someone else enjoy the bits
     
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  3. At least it’s got a lovely carbon v-piece….
    Too soon?
     
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  4. Several engines on eBay, some with provenance and even a limited guarantee. Andy
     
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  5. Thanks Andy, Been looking at those…… could be an effective answer.
     
  6. There is a lot I like about this bike, especially the great times we have had together :heart_eyes:

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  7. Yep, agreed, either need to refurbish the whole engine, or swap another in, which would probably be the easiest, quickest, and probably cheapest option.
     
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  8. I would say get a used engine but I think most are getting leggy now. Fine for road uses but you are going to be beating on the thing. I’d get yours at least stripped to see if it’s otherwise good, for a few hours labour, and then if everything else is okay you could replace the bearings and jobs good.
     
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  9. Thanks Phil, The strip has been done, all boxed and sorted.
    She led a pampered life with constant oil, filters, belts etc… but unlike my other engines, never had the engine fully apart.
    Crank journal beyond recovery as this is where the front cylinder shells failed. Rear side is fine as is rod & piston.
    Front rod suffered extreme heat, so a replacement pair needed.
    Front piston needs closer inspection to see if any damage from shell failure and head contact.
    Gearbox undamaged.
    Cases undamaged.
     
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  10. Rebuild it with ti rods and forged pistons :heart_eyes:
     
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  11. I wouldn’t admit to being envious of another man’s tools…
     
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