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Seized piston on 13 kx250f

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I f'd up and installed oil filter backwards...rode the local track for about 20-30 seconds and motor locked up. Small kick and she broke loose fairly easily. Took apart motor last night and found rings completely gone...melted aluminum stuck to cylinder but didnt hone to see if damage was actually done to nickesil. Crank has no play up and down but alittle bit side to side which is normal? valves all look straight, cams are good as well as bearings...head doesn't have a mark on it...basically question is should i send head in for new valves and rebuild bottom as well as the obvious piston and ring replacement?

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You'll want to tear the motor completely down and split the cases, no matter how clean you think you have it there will still be metal shavings inside.

Even if the cylinder cleans up and looks ok I wouldn't reuse it. Theres sure to me some heat warpage.

You should be good to go with a new cylinder and piston. DO yourself a favor and use a Cylinder works cylinder/piston kit.

They can be found on Ebay complete with gaskets for around $400. Better quality than OEM and cheaper than retail.

Might even be a good time to go to a cylinder works 270 kit. these bikes rip with the 270 kits. And it goes together just like OEM.

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You'll want to tear the motor completely down and split the cases, no matter how clean you think you have it there will still be metal shavings inside.

Even if the cylinder cleans up and looks ok I wouldn't reuse it. Theres sure to me some heat warpage.

You should be good to go with a new cylinder and piston. DO yourself a favor and use a Cylinder works cylinder/piston kit.

They can be found on Ebay complete with gaskets for around $400. Better quality than OEM and cheaper than retail.

Might even be a good time to go to a cylinder works 270 kit. these bikes rip with the 270 kits. And it goes together just like OEM.

I agree, tear it down

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I don't mean to offend you or to be rude but next time, use the manual. It'll save you a load if hassles. And like nesc said, you should tear down the bottom end, there has to be shavings in there. Good luck with the bike bro and you should go for the 270 kit.

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Thx for input guys, think i will split cases for sure...as for 270 kit i am very interested but i see mixed reviews on it. I've ridden an '10 yz with a 290 kit and thought it was awesome, love the low end torque. I will have to get mapping done for 270 and different cams as well to make it run from what I've read past couple days. But will it give me that nice bottom end like that yz had? Not too much info or reviews in it.

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dont trip Sordze.  I just picked up an 11 kawi 250f with EXaCT SAme PROBLEM. . best friend had rekluse clutch put in and the ding dong mechanic put the oil filter in backwards and off he went. Bike siezed in 2-3 minutes and I'm up in the air as well.  Are you gonna use the old crank???  whats the chances that my crank will still be good, havnt looked yet???  I was wanting to go big too.  athena makes a 300cc, havnt heard anything bout it

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I ended up ordering stock size cylinder works cylinder and piston and new cam chain...sent the bottom end to a mechanic to pull apart and see if any damage...should know more by Friday. As for the head i got a deal on a pro circuit ported and polished head with pc valves stage 2 hot cams(one race on it). The box of parts i purchased also came with brand new pc cams and springs as well as stock valves. My stock head and cams look in perfect shape but the valves stems looked cooked so i haven't decided what route in gonna go yet...ported head and brand new cams or stage 2 hot cams? Or stock head with pc valves and cams? Etc etc...if i don't use the pc cams and springs i will probably try and sell them to recoup cost on my fairly expensive oil change...

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It is crazy that it is so easy to put that filter in backwards.  It is either an engineering oversight or a diabolical scheme.  The crank has plenty of side-to-side play in spec, so that is not an issue.  Up and down play is a potential EIDIT:  DEFINITE problem.  If the thing turns smoothly and the con rod is not bent, I see no reason to tear it down (other than it is fun and peace of mind . . . but, I digress.  Pull the cylinder and give it a good scrub with green Scotch Brite and WD-40.  That will either make you happy or tell you the cylinder needs to go in.  If the head has no visible scars, you don't need to do anything with it.  If you want to see if the valves are damaged, place it valve down on a plate and inject it on the carb and exhaust side with some non-toxic fluid (or gas, whatever, just be safe) to see if the valves hold the fluid.  My guess is they hold, your cylinder is fine, you need a new piston and rings and that tear-down adventure can wait.  Pictures help, though, so send them along if you want really good advice.  

Edited by Dragon67

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