2002 YZ250 top and bottom rebuild project

[adzski]

hey everyone

my names adam, from the land of oz hahah

well i shed some light on the situation i bought the yz250 here for $1800 its cheap here for that year so i expected problems but not to this magnitude, anyway on the first ride excluding the test ride, i was just about to take it in and heard a weird noise then it bogged out, kicked it again and it wouldn't start and then the kick start would go down, problem was the piston kinda exploded and went down in the crank and fucked everything up  so its getting a top and bottom rebuild.

progress so far is the motor is completely out, and ready to be rebuilt.

this is the rebuild kit im going with
http://www.ebay.com.au/itm/Yamaha-YZ-250-Complete-rebuild-kit-Crankshaft-Piston-Gaskets-2003-2011-/271033781478?pt=Motors_ATV_Parts_Accessories&hash=item3f1adf4ce6

new plastics kit
http://www.ebay.com.au/itm/121074255182?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648

will be ordering all of the above in a day or so, but im going away for a week for a holiday so the rebuild wont take place for a week.

and some progression pics of whats happened so far.

when i first started pulling the top end off!


quick pic of the piston


with the motor pulled out


 

[Stusmoke]

Damn I almost thought this was MY YZ250 that I sold a few months back. What model is it? I sold my 01 for $2000 but it still had some life left in it.

[factoryX]

That engine rebuild kit is nice

[evo550]

Ummm, where have I seen that piston before ??

[gc8steve]

Are you replacing the cylinder as well ? looks like it may have been sucking in dust too, have you found what caused the failure or are you just assuming fatigue ?

[adzski]

theres two threads on it other is here. prob where u seen it
http://twostrokemotocross.com/forum/technical/yz-250-engine-seized-i-think/

im assuming poor maintenance, aswell as age of the bike and as you said fatigue, i dont think the piston was ever changed, its a 02 so its a 11 years old with out a piston change . though previous to this bike i had a 1992 rm250 fully restored well to my taste, but i didnt do the engine much was young never changed the piston but maintend well cleaned filter changed oil, ran the correct ratio and never had a problem and my brother had the bike previous with no problems got pics if interested?

and yeh i bought a new barrel
Update.

rebuild kit arrived + new plastics fitted pics soon

about ready to split cases change crank and bearings and the bottom end back in the bike.