Piston check advice

ktm-5
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ktm-5
Edited Date/Time 6/16/2018 7:43pm
I have a 16 ktm 250f and was wondering what you all thought about how the piston looks. I'm not sure exactly how 4 stroke pistons should look and also if you look at the close up pic is that spark plug arc? It almost looks like the plug was arcing off it but I'm not sure so I'm hoping some experts can chime in, thanks.

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ktm-5
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ktm-5 6/15/2018 2:12pm
6/15/2018 2:12pm

Exhaust side


Intake side

ktm-5
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ktm-5 6/15/2018 4:01pm
6/15/2018 4:01pm
Paw Paw 271 wrote:
How many hours on the piston?

Paw Paw
20.7. Motorex oil every 3-5 hrs

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Paw Paw 271
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Paw Paw 271 6/15/2018 7:18pm
6/15/2018 7:18pm
Overall the piston looks good. It shows to be a very little bit rich in fuel mix. Burn pattern looks very good.
I do see what I would call excess wear on the skirts of the piston for the run time stated.

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ktm-5
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ktm-5 6/15/2018 7:34pm
6/15/2018 7:34pm Edited Date/Time 6/15/2018 7:36pm
Thank u paw paw. Any idea why there would excess wear on the skirts? Cyl was redone 20.7hrs ago and I'm a freak when it comes to air filters. I run either non ethanol or vp pro6. Also does it look like the plug is or has hit the piston or could be arching on it? The plug did not show any obvious sign
CarlinoJoeVideo
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CarlinoJoeVideo 6/15/2018 10:12pm
6/15/2018 10:12pm
ktm-5 wrote:
Thank u paw paw. Any idea why there would excess wear on the skirts? Cyl was redone 20.7hrs ago and I'm a freak when it comes...
Thank u paw paw. Any idea why there would excess wear on the skirts? Cyl was redone 20.7hrs ago and I'm a freak when it comes to air filters. I run either non ethanol or vp pro6. Also does it look like the plug is or has hit the piston or could be arching on it? The plug did not show any obvious sign
Could have been detenation under heavy load?
ktm-5
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ktm-5 6/15/2018 10:15pm
6/15/2018 10:15pm
ktm-5 wrote:
Thank u paw paw. Any idea why there would excess wear on the skirts? Cyl was redone 20.7hrs ago and I'm a freak when it comes...
Thank u paw paw. Any idea why there would excess wear on the skirts? Cyl was redone 20.7hrs ago and I'm a freak when it comes to air filters. I run either non ethanol or vp pro6. Also does it look like the plug is or has hit the piston or could be arching on it? The plug did not show any obvious sign
CarlinoJoeVideo wrote:
Could have been detenation under heavy load?
Oh yeah, I didn't even think about that, so that could've been from to low of an octane for a heavy load??
Paw Paw 271
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Paw Paw 271 6/15/2018 10:27pm
6/15/2018 10:27pm
I am concerned about the cylinder to piston clearance. If too much then it would allow the piston to wobble and cause excess wear. Also if under excess load at low rpms it will show excess wear on the piston skirt. Understand, you will always have some wear on the skirt, but this just looks excessive for the amount of hours posted or the hours of use were much more than reported.

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ktm-5
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ktm-5 6/15/2018 10:36pm
6/15/2018 10:36pm Edited Date/Time 6/15/2018 10:37pm
That is one measurement I did not take because I had millennium redo the cylinder 20.7 hrs ago with the piston pictured and I just assumed there is no way it would be out of tolerance after 20hrs, unless they screwed up but I did send the piston with the cylinder. As for the amount of hrs I gave that is exact amount because I have always had hr meters on our bikes since the minis, and I'm not a guessing kind of guy, I want to know exactly, lol. I do know some piston wear will happen but wasn't sure if it was too much. If my son did not let the bike fully warm up at times would it look like this? I know 2 strokes will show the 4 corner sign if not warmed. Another side note also is the bike is modded fairly good so I don't know what kind of extra wear that would show if any. Thanks again
lumpy790
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lumpy790 6/16/2018 12:06pm
6/16/2018 12:06pm
ktm-5 wrote:
That is one measurement I did not take because I had millennium redo the cylinder 20.7 hrs ago with the piston pictured and I just assumed...
That is one measurement I did not take because I had millennium redo the cylinder 20.7 hrs ago with the piston pictured and I just assumed there is no way it would be out of tolerance after 20hrs, unless they screwed up but I did send the piston with the cylinder. As for the amount of hrs I gave that is exact amount because I have always had hr meters on our bikes since the minis, and I'm not a guessing kind of guy, I want to know exactly, lol. I do know some piston wear will happen but wasn't sure if it was too much. If my son did not let the bike fully warm up at times would it look like this? I know 2 strokes will show the 4 corner sign if not warmed. Another side note also is the bike is modded fairly good so I don't know what kind of extra wear that would show if any. Thanks again
Pistons tend to wear faster than cylinder
BobPA
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BobPA 6/16/2018 7:43pm
6/16/2018 7:43pm
Paw Paw 271 wrote:
I am concerned about the cylinder to piston clearance. If too much then it would allow the piston to wobble and cause excess wear. Also if...
I am concerned about the cylinder to piston clearance. If too much then it would allow the piston to wobble and cause excess wear. Also if under excess load at low rpms it will show excess wear on the piston skirt. Understand, you will always have some wear on the skirt, but this just looks excessive for the amount of hours posted or the hours of use were much more than reported.

Paw Paw
Agreed. Check your clearence Clarence. I would bet it is set up a little too loose.

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