2001 Kx 65

[pdhj1990]

Yesterday, the piston in my son's 2001 KX 65 froze. I think he rapped it out to much in 3rd gear before shifting. Now, I must take the bike into the shop to determine the damage.

Although I'm mechanically inclined, I know there are countless viewers/riders on this website that have forgotton more than I know. With that in mind, I'd appreciate any words of wisdom i.e. possible issue (s), possible fixs, possible cost, etc.

Thanks.

 

[Martin Cole]

Many things could be behind a seizure so you'll have to strip it to determine where the fault lies. Check the obvious first - such as correct spark plug?, has it run out of coolant?, main jet too lean?, sufficient oil mix in the petrol? etc.
You won't know about costs until you remove the barrel. Obviously the piston, rings and small end bearing will need replacing. If you are very lucky the barrel may still be serviceable with some light cleaning up, but if it's scored it will need replating at the very least. Deep scores may have to be filled with weld before it can be bored and replated - adding to the cost.
If there is little or no coolant in the radiator, check for leaks around the radiator core and make sure all the pipes are sound and properly secured. If there's nothing obvious strip the water pump and make sure the seals are good. You may find the oil has emulsified when you drain the gearbox - this could be a sign the pump seals are shot.
If the bike hasn't been stripped for a long time the piston may have become very worn on its front face (exhaust side). If the wear here gets excessive it causes piston slap which leads to damage of the bore plating and stress fractures in the piston skirt. If part of the skirt has broken off some fragments of alloy may have become nipped between the piston and the ports - this usually results in deep scoring. I've also known circlips fly out of the small end boss and get trapped between the piston and transfer ports. If something like this has happened you need to also strip the whole motor to make sure there is nothing lurking in the crankcases that may get thrown up next time start it and cause the same thing to happen again.
MC

 

[pdhj1990]

Thanks Martin for the feedback. I'm going to take the bike to a shop that will determine the damage :(

Paul