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I have Bajaj 100cc bike..today, it stopped all of a sudden and the kicker got jammed. I later realized it ran on low engine oil. What will be possible damage? i can able to toe the bike as there is no problem in wheel rotation.

  • Sounds reasonable that the engine has seized (the piston has seized in the cylinder). However could you give some more information about this engine? Is it a two stroke? Is it aircooled? – Markus Feb 7 at 8:13
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Sadly, the probability of your engine being sized is fairly high. When the oil runs very low, the bearings on the crank shaft, and the pistons in the cylinders heat up very quickly due to lack of lubrication.

In an attempt to work the engine backward and forward to check if it is truly sized, I recommend that you do the following.

  • Ensure there is oil in the crank case.
  • Remove the spark plug.
  • Pour a little oil into the cylinder through the spark plug hole to lubricate the cylinder walls.
  • Place the bike in its highest gear and rock it forwards and backwards so that the engine tries to turn.

Normally, the engine should turn with very little resistance without a spark plug, especially if the cylinder walls are fully lubricated. If you can't see any movement, or aren't sure if the engine is turning, you can slide a long piece of soft wire into the cylinder until it touches the piston, and repeat the process. If the engine is turning, the wire will be pushed up and down.

If the engine did seize, but you are able to work it loose, you will probably have to hone the cylinder, and replace the piston rings. If the crank shaft bearings got too hot, the damage might extend to the rods, bearings, etc. Also, the head might have warped. Fixing this is doable without great expense, but will require moderate mechanical ability.

Follow the steps to check for damage, and comment your findings for further suggestions.

  • I agree with your method of determining if it's seized, but not your assessment of what it takes to fix. Repairing a seized engine is a big chunk of work, requiring specialist tools and knowledge, it's not something a home mechanic with moderate ability would be able to do. In many cases it makes more sense to replace the engine entirely rather than try and fix it. – GdD Feb 7 at 9:30
  • @GdD, for normal car engines I would entirely agree, but for a 100cc Bajaj bike, it would be relatively easy. They could dingle ball hone the single cylinder, and if they head was warped they could flatten it with a file (I know it sounds completely sketch, but it actually works.) If they were to attempt to rebuild an engine, this would be an excellent first rebuild. The value of the bike is currently negligible, so if they made a mistake they wouldn't be any worse off than at present. The knowledge and experience gained through this rebuild would serve them well for future projects. – the_storyteller Feb 7 at 20:09

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