ttr125lerider Posted April 1, 2010 hey everybody its been a while since ive visited this forum...i no longer have my yz125, but still ride my brothers 250f on occasion. Being the more mechanically inclined person in the family, I figure its time to rebuild the 250f. I did my 125 a few times, and could do 2 strokes blindfolded...not really saying much. I read the 2007 rebuild thread, and was just looking for a little more info. any good top end kits to go with. I remember wiseco used to make good stuff. and whats the deal with the timing chain. replace that or no. I guess ill go ahead and check the valve clearance while im in there, but im hoping we can keep this rebuild to around 250 or less. thanks Share this post Link to post Share on other sites
ronbuell My Rides (17) Posted April 1, 2010 Plan on a gasket set, piston, rings, wrist pin, clips, cam chain, and check some things. BE SURE to look at the small cam chain sprocket on the left crank end. If the teeth are sharp and pointed, replace the crank. If the wrist pin is loose in the small end, replace the crank. If the rod is loose on the big end, replace the crank. And, if the crank bearings are loose in the case, replace them too. If the valves have a history of closing up, then replace them and have the valve seats cut. You will need shims if you do the valves. We ran a hone for about 6-8 turns slowly thru my cylinder to clean it up and when we measured with the new piston, it was right in the middle of the spec. Wiseco is a good product. Yamaha sell parts individually so you can buy only what you need. Good luck. Share this post Link to post Share on other sites
