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2001 kx250 piston damage

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Hi guys, i have a question, .image.jpg i have a kx250 2001 i bought last year ran fine up untill now, i took piston out to notice it had some unfamiliar marks, image.jpgimage.jpg barrel has no damage whatso ever, but half the top ring is imbedded in the ring groove.

So i bought a wiseco, changed all gaskets, orings, rings ect put all back together and was running fine, bike died on me other day so i took the exhaust off and looked through the port and it does seem like it has done the same thing, could any one give any info on what might be the problem, any input would be greatly appriciated many thanks.

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power valves hitting the piston?

I thought the same, but she ran fine for a year before hand, and it didnt feel like it was hitting whilst riding... Thanks for reply

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I have no experience with wiseco. But 99 percent of people in the kawi 2stroke forum say don't use wiseco pistons. They are garbage lol.  This has nothing to do with your problem, just random input on piston choice...

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I have no experience with wiseco. But 99 percent of people in the kawi 2stroke forum say don't use wiseco pistons. They are garbage lol.  This has nothing to do with your problem, just random input on piston choice...

 

 

99% is an exaggeration, and they're wrong.

 

I've run Wisecos in every bike I've owned for over 30 years without a single issue. My KX 250 has a Wiseco Racer's Choice in it right now, and it will last longer than the OEM pistons.

 

When people have problems with Wisecos, it's their fault 100% of the time. They either didn't install it correctly (improper clearance or break-in) or are too stupid to warm their engine up properly.

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99% is an exaggeration, and they're wrong.

 

I've run Wisecos in every bike I've owned for over 30 years without a single issue. My KX 250 has a Wiseco Racer's Choice in it right now, and it will last longer than the OEM pistons.

 

When people have problems with Wisecos, it's their fault 100% of the time. They either didn't install it correctly (improper clearance or break-in) or are too stupid to warm their engine up properly.

 

 

genie-jaw.jpg

 

Will take your word for it.  Maybe I was thinking of the bottom end?  Read somewhere they used cheap bearings on the bottom end, resulting in bad failures.  Guess it pays to do a good inspection regardless and be sure you install/heat cycle/get the right parts.

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genie-jaw.jpg

 

Will take your word for it.  Maybe I was thinking of the bottom end?  Read somewhere they used cheap bearings on the bottom end, resulting in bad failures.  Guess it pays to do a good inspection regardless and be sure you install/heat cycle/get the right parts.

 

 

You're talking about Wiseco cranks. Yes, they seem to have quality issues, and a LOT of people have reported failures with them. 

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My power valve can not reach the piston even at full stroke. How clean was the power valve? Mine was very dirty and carboned up. Maybe a piece of carbon cam loose and got caught in there. Was the ring end gap in the right place? If you took your power valve apart for cleaning did you reassemble it properly?

Edited by condor74

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...

My power valve can not reach the piston even at full stroke. How clean was the power valve? Mine was very dirty and carboned up. Maybe a piece of carbon cam loose and got caught in there. Was the ring end gap in the right place? If you took your power valve apart for cleaning did you reassemble it properly?

Thanks for the reply guys, to be honest i havent cleaned out the power valve that picture of the piston was the old pro x i took out originally, the engine hadnt been touched, up untill after the failure, i know i did have a problem with piston sizes so i assume the jug has been resleeved as the original piston size was too small and had to order larger, would this play a part, as the owner before didnt take into account the size of the powervalves, only confusing issue is the fact that i drove it for nearon a year before the failure... thanks again

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If you are running a larger than stock bore, this will put you closer to the flapper valve.  Being as it is something that just happened, I think you need to take the power valve apart.  In its normal travel, it should never hit the piston.  I did some research and found a few incidents where the pin on the valve may have broken allowing the flapper to slide down further into the cylinder.  This would definitely cause catastrophic piston damage.

 

Take it apart and take pictures, I am sure we are all curious as well.

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Okay will take tpart tomoz after work, i know from the last time that there was no jug damage what so ever, i was surpised to be fair, i would be interest to know why the valve would cause the damage on the piston to lip up image.jpgimage.jpg surely this means the valve is only cause damage on the piston down stroke... Correct me if im wrong.. Thsnks again for replys people

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Right, engines out heads off jugs off and this is what ive found...image.jpgimage.jpg the piston in atm is only bout 3 hours old if that,image.jpg powervalve is pretty clogged up and there is no scores on the jug itself... image.jpg hope these photos help...

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It's not rocket science bro.

 

Something is causing the main valve to contact the cylinder. Either the parts are worn or something is pushing on the valve the wrong way, maybe installed wrong or the actuator arm causing it.

 

I don't have a cylinder in front of me, but I think it could only be worn to do that.  Take it all apart and clean all the spooge off.

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It might not be rocket science to you bro lol but, as i havent encountered something like this before, and i havent touched the powervalve myself i was only asking for input and peoples opinions on what might be the problem... Thanks for your opinion and i will check these parts for ware...

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Wow, this a strange one, like you dont already know!!

I would look for tell-tale on the tip of the powervalve, if it is contacting the piston there should be some significant wear.

On the opposite end, I 'd check the piston/bore clearence at both the bottom and top of the bore.  A loose piston down in the bore could cause excessive slap loads.

Though normally you would see it on the skirt of the piston as well (maybe the skirt is cracked??).  Hopefully it is just a clearence thing on the power valve. But I am doubtfull :(

Let us know and good luck.

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Can you reach into the exhaust port and feel if the main part of the power valve is protruding into the cylinder in any way.  Either way You will have ot disassemble the power valve.  To get the main flapper valve out. Remove the small allen bolt on the actuator shaft.   Slide the shaft out and remove the 2 small retaining bolts that are holding the power valve flapper into the cylinder then in theory the power valve will pull out in 2 pieces.  I say in theory because it will most likely have a metric shit ton of carbon build up on it and will not come out easy.  It took me about 20 minutes of pulling and pushing in and out to get it to finally come out.  I took it to a  wire wheel and removed all the carbon from it.  I then cleaned the cylinder area as best I could with a wire brush.  When it was all clean, I ressembled using a little 2 stroke oil to make sure things moved freely.  When it was done, I also used a wire brush and a file to remove the rest of the carbon from inside the ports.   When I was done is moved in and out like smooth like butter.  There is another part to the power valve to clean and service that I did not describe here so know that once you do that you are not donehttp://www.youtube.com/watch?v=HkPU6V-cIxE.

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