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02 kx250 engine rebuild

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Hey guys,

A friend of a friend is gonna sell me the bike for $500cdn with a exploded piston. Have yet to see the bike, but supposed to be in good shape. Just wondering if any of you guys have been down this road before, and what kinda money I'm lookin at to get her up and running? I would assume the head is done for and needs to be replaced

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You will have to adjust for shipping/import/export stuff, but here in the US, I would expect it to be about $600-$650 US.

Send the cylinder to Millenium Technologies or some other similar place. They can usually repair your cylinder. I would also purchase a piston/rings/wristpin/bearing from them at the same time. $190-$250 depending on damage.

Check someplace like motosport for a complete engine kit. $420

You might be able to shop carefully and pick and choose to get the individual parts cheaper?

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An exploded piston means there is metal debris down in the lower end (crankshaft) and the cases will need to be split. Also more then likely the cylinder will be damaged and it will need replating, theres a place in Port Moody (mongoose) that replates for $290 (only place in BC actually) At this point you might as well rebuild the entire engine, if you have a shop in BC do it all your looking at over a grand easily. Doing it yourself and mail ordering all the parts, your in the $800 range, since our cdn dollar is strong right now.

If people would replace pistons at timed intervals there would be a lot less of these forced rebuilds going on :thumbsup:

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I would go with OEM parts, the parts are actually cheaper now.

Like the above posted splitting the cases is mandatory, at least the cost is not house mortgage money.

If I had a dollar for 'blown up 4t' bikes 250F/450F bikes, I would have enough to buy another house. :thumbsup:

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Piston, rings, pin and bearing 125.00

Complete gasket kit 60.00

Crank and bearings 200.00

Replate cylinder 200.00

TOTAL 585.00

This is assuming its a 2 stroke

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likely scenario is:

split cases,rebuild or replace crankshaft

replace main seals and bearings

top end gasket kit and a tube of Kawabond to seal the cases back

replate and/or repair/replate the cylinder

used head off eBay

new piston kit (piston, rings, top end bearing, two circlips, wrist pin)

Don't forget that since the engine was probably neglected, that the forks need a rebuild, shock needs a rebuild, check chain and sprockets, check air filter, carb, various bolts and nuts, etc.

Good luck!

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