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Rm250 2006 engine rebuild

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so on the weekend the skirt of the bottom of the piston let go on my rm250 2006.

the motor would not turn over via the kick starter and was jammed, guessing due to debries in the bottom end.

it was how ever shut down after it sounded horrible and didnt seize as such.

 

the piston is the standard size and the bike was running well before this happened

 

iv owned it for around 6 weeks and the engine was "rebuilt" by the last owner due to the air filter failing and it sucking up loads of dust thus wrecking the bearings in the bottom end.

 

anyway i can handle getting the jug bored and honed to the next oversize and a piston to suit.

 

however even looking by eye i can tell that the crank doesnt run true and runs in a some what eplicatial fashion when view from the stator side or the primary drive side.

i believe this is called crank deflection, the engine also has a spot where its harder for you to turn it over by hand - keeping in mind the top end has been removed and the debries have been mostly cleaned out from the bottom end.

with the clutch and drive gears bolted up its basically impossible to turn the motor over by hand, due to the primary drive gear not running true.

 

now im guessing this is an issue.. and probabley a result of the engine losing its skirt and a piece of piston jamming inbetween the case and the crank shaft.

 

what is the course of action to fix this problem !

any help would be great cheers.

 

 

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Hey mate, the exact same thing happened to my 06 last year. To be on the safe side I ended up buying a Hotrods bottom end kit to put in. Turned out to be the right decision after finding that the main bearings had a small amount of play which would have caused the piston slap that broke the skirt of the piston. Even though it was a couple of hundred more I now have a fully rebuilt motor that is performing beautifully. Good luck with yours.

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You can't bore nikasil. You need to get it re sleeved.

I'd split the cases and go through the motor to make sure all is well. THIS IS WHY YOU TAKE HER APART BEFORE AND AFTER YOU BUY!

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You can't bore nikasil. You need to get it re sleeved.

I'd split the cases and go through the motor to make sure all is well. THIS IS WHY YOU TAKE HER APART BEFORE AND AFTER YOU BUY!

well the engine builder said you can hone the nikasil bore with a diamond hone, going to see how it comes up after a hone, if its no good ill be getting it recoated.

cases are being split and the crank is getting rebuilt.

 

who the hell would disassemble a bike after they buy it? i went over it making sure it was safe replacing worn parts, but honestly strip the motor down just to check - your nuts, think this failure has prob been atributed to me overheating it couple weekends before, piston shows signs of over heating and most likley where everything went wrong.

 

in anycase it will be back big and better then ever soon. 

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well the engine builder said you can hone the nikasil bore with a diamond hone, going to see how it comes up after a hone, if its no good ill be getting it recoated.

cases are being split and the crank is getting rebuilt.

 

who the hell would disassemble a bike after they buy it? i went over it making sure it was safe replacing worn parts, but honestly strip the motor down just to check - your nuts, think this failure has prob been atributed to me overheating it couple weekends before, piston shows signs of over heating and most likley where everything went wrong.

 

in anycase it will be back big and better then ever soon. 

Hahahahaahahaha, you got alot to learn bud.

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