Need professional opinion on a piston

Joined
Sep 12, 2006
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#1
My son's KX100 now has 15 + hours on it, so I want to install a new piston even though the compression is still at 170PSI. I am concerned about skirt wear on the cast piston and knowing that Kawi's stock cylinder plating is crap these days (on 2004 or 2005 and newer cylinders). With this info in mind I am a little concerned about using a Wiseco forged piston, and so I am considering an OEM piston. This winter I am sending the top end to Eric and I will run the Wiseco piston from that point forward.
But in the mean time what would you guy's put back in the stock cylinder with the soft stock plating? I want to get through the summer with out ruining the cylinder or blowing a top end.
 
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Mar 26, 2007
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#2
The main thing I would be worried about is the rings. They rub more on the cylinder walls than the piston does..


A forged piston is just a "tougher/harder" (unscientific i know) metal, it can take more of a beating. I am unsure if it expands differently than a stock piston when heated. I assume if any, not much.

If you are concerned about the piston rubbing, make sure you measure it before it goes in.

Also, I believe some companies make pistons with anti-friction coatings. They have a black coating all over the piston.

Wiseco makes a good product, I wouldn't worry too much about using their stuff over stock in just about every situation.
 
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#3
I have used a lot of Wiseco pistons over the years but this cheap cylinder plating worries me. The Wiseco forged piston does expand differently than the stock cast piston, that is why I am concerned about this situation. Maybe I just worry too much?
 
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#4
If your are concerned about expansion rates, you might want to look at Hypereutectic Pistons. They seem to have a smaller expansion rate than forged and cast pistons.


It would seem to me that a Hypereutectic Piston with an anti friction coating would be the "best" for a crappy cylinder coating.
Please keep in mind that you will probably sacrifice in other areas (strength, etc) to achieve this.



Do a bit of googling, or just call Wiseco and ask them :)
 
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#6
my friend bought a new kx100 in '06, and he put fmf exhaust and a wiseco piston in it as soon as he got it. He raced it every weekend for about a year and when he had it apart to put the new top end in it the cylinder was immaculate. My '03 kx100 still has the stock plating and I race as well... If you are really worried about it run a racing fuel like VP, they burn much cooler and thus would minimize the piston expansion.
 
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#7
tyler_43 said:
my friend bought a new kx100 in '06, and he put fmf exhaust and a wiseco piston in it as soon as he got it. He raced it every weekend for about a year and when he had it apart to put the new top end in it the cylinder was immaculate. My '03 kx100 still has the stock plating and I race as well... If you are really worried about it run a racing fuel like VP, they burn much cooler and thus would minimize the piston expansion.
Cool, Thanks!