I gave my bike (Yamaha FZS ver 2.0) to an authorized service center for it's first-time service. The mechanic didn't fit the drainbolt (which is under the engine) properly causing the engine oil to leak/drain completely.

Unaware of this, I drove for ~50kms till the engine seized. The service center manager is suggesting replacing the borekit (and not the engine ). The bike is under warranty.

Please suggest the best course of action also explaining why the particular parts/procedure should be replaced/carried out.

  • 3
    Theres a lot more that requires oil and could have sustained damage, bearings, half shells, piston rings, valves/rockers, cams all require oil to work correctly. Stripping the engine and inspecting each is the only way to correctly repair it.
    – Mauro
    Apr 27, 2015 at 8:53
  • 3
    Agree with @Mauro. It may actually be cheaper for them to replace the engine at this point due to the amount of labor hours which would go into doing the inspection and refit. I would highly suggest you press for this with the dealer/service center. Apr 27, 2015 at 11:39
  • seconded. This being completely their fault, you must press for an engine replacement. Anything else would be less than fair.
    – chilljeet
    Apr 28, 2015 at 4:16
  • 1
    If you're unhappy with the offer from the dealer you should raise it with the National distributor. This is a risk to their reputation as well, and in their interests to see that it's put right properly. Apr 28, 2015 at 9:04

1 Answer 1


The majority of the damage is more than likely in the bottom end of the motor.

Bottom end components such as plain bearings for the connecting rods and the crankshaft main bearings are more than likely absolutely destroyed. Plain bearings rely on oil pressure to push oil in between the journal and the plain bearing creating situation called hydrodynamic lubrication where the surface of the journal is 'floating' on a thin film of oil between the journal and the plain bearing. Without hydrodynamic lubrication, which requires oil pressure, the bearing and journal will begin to degrade from metal to metal contact. Once these surfaces touch one another they begin to self destruct. In so doing, the crankshaft bearing surfaces for the offset and main journals are more than likely destroyed.

There is a distinct possibility that the engine cases are damaged as well. As the plain bearing for the crankshaft are destroyed due to lack of lubrication, the crankshaft can wear through the soft lead and nickel plain bearings and into the aluminum of the crankcase.

Oddly enough, the bore of the cylinder may be just fine. The piston and rings need splash lubrication and may have survived the event.

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