OEM KTM Piston questions

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2/1/2019 6:05 PM
Edited Date/Time: 2/1/2019 6:07 PM

I just bought a new OEM piston for my 2014 KTM 450 sxf and I have some questions about it. I've always bought Weisco replacements so some things seemed a little off to me.

First I wonder if this piston has been returned. The box had a seal on it(it wasn't broken like in this pic), but part of the box was ripped.
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When I took the piston out, I noticed a couple of spots where the coating had worn off. You can see round spots on the piston bridge that have worn off. Top middle of the first picture and also last one on the piston skirt.

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The piston came with the rings and wrist pin already installed. All Weiscos I installed, I had to install these on the piston myself.
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And the last thing, there is this extra wire thing I can't figure out what it is. It doesn't look like its part of the oil ring. It's much larger than the piston so I'm not sure what it's used for.
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Is this all normal for a new OEM piston and does anyone know what that extra wire is for? The piston kit came with no instructions either.

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2/1/2019 8:20 PM
Edited Date/Time: 2/1/2019 8:21 PM

I'd be sending/taking that thing back. I wouldn't be paying good money for a piston that at best has had a rough shelf life. I can't answer about KTM 450 pistons coming with the rings installed but can say the small bore Vertex Pistons don't come installed. The coating being worn off on the skirt would be reason enough for me to send it back.

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2018 KX450F
2005 KX250
2003 KDX 220
1984 KX 80
1982 RM 80
1980 RM 80
1977 XR 75
1969 Honda Mini 50

2/1/2019 10:49 PM
Edited Date/Time: 2/2/2019 12:12 AM

I’d definitely return that. I’ve never seen a piston come with the rings installed... I believe, the ring with the wire in it is a gapless style oil ring. Although, it’s a little hard to tell from the photo...

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2/1/2019 11:57 PM

The last picture shows the oil ring that should be behind the ring thats now placed on your piston as an oil ring. At least thats how it is in these new oem cp pistons that also come with pre-installed rings.

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2/2/2019 12:13 AM

PsyCo wrote:

The last picture shows the oil ring that should be behind the ring thats now placed on your piston as an oil ring. At least ...more

That’s bizarre... So you have to remove the rings from the piston the check ring gap?

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2/2/2019 2:01 AM

PsyCo wrote:

The last picture shows the oil ring that should be behind the ring thats now placed on your piston as an oil ring. At least ...more

Paul_Pitzonka wrote:

That’s bizarre... So you have to remove the rings from the piston the check ring gap?

Yep

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2/2/2019 12:33 PM

Looking at it more, it looks like that big ring is part of the oil ring. It fits but I guess the best way to find out is to check my stock piston when I pull it.

Still not sure about the rings and wrist pin pre-installed. If it's OEM they did a sloppy job with scratching the piston
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2/3/2019 8:37 AM

That wire goes behind the oil ring scraper. That's what gives the oil ring it's tension. Without that you'll have a real smokey SOB on your hands.

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Race Bike: 2018 KTM 350SXF

Other Bikes: 1985 CR80R, 1990 CR250R, 1998 PW80, Specialized Fuse Comp 29.

Sold: 2016 YZ250F, 2012 CRF250R

2/4/2019 11:01 AM

So then the piston has probably been opened before? I'm thinking with the marks on it and the rings being all weird that someone might have done a dry fit and then returned it?

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