Any reason not to run oem Yamaha pistons?

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8/31/2017 7:08 AM

Recently I bought a 2013 yz250 with only one owner from new which had been sat in a garage for over 2 years due to injury. The bike came with the full spares kit! I began stripping the bike yesterday and found it was fitted with a vertex piston, which got me thinking why would someone put a vertex in there when they have a genuine top end kit sat there? The piston fitted was a size A (66.34) even though the cylinder is clearly stamped with a C, and the piston in the spares kit is green (66.36). I'm guessing that's why the piston looked like this when I removed it......Photo

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8/31/2017 9:19 AM

I like forged pistons from wiseco more than cast oem ones. Castings arent as strong. You gotta let forged pistons warm up but no big deal. Oem parts are good as long as you follow service intervals.

You cant go wrong with pistons unless you buy namura.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

8/31/2017 3:31 PM

OEM stuff is usually a really good way to go, I prefer them over aftermarket usually. To keep the engine fresh and just to be safe I change them out as regularly. Use an hour meter.
Maybe the P.O. bought the spare kit after the Vertex was installed?

+1 on the Namura stuff being good for AR-15 target practice, just don't make the mistake of putting one in an engine.

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8/31/2017 3:40 PM

+2 on Namura, cheap eBay pistons would never put one in my bike, a disaster waiting to happen.

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9/2/2017 2:37 PM

I ran both OEM and Wiseco in my Yamaha. Never had problems with either, and honestly never noticed a difference between the two either, other than the price. I changed the rings around 20 hours and did a full top end at around 40. That was on a 125 though, if it matters.

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9/4/2017 2:06 PM

oem yamaha pistons are top notch, just run an hour meter and keep the hours reasonable. Pro x is also a great choice and made in the same factory and oem yamaha pistons


I had a customer come in with a yz250 that "wasnt running right" even after 200 hours and shattered skirts this 13 yz250 still ran!

Photo

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9/6/2017 3:05 PM

What's considered 'reasonable' hours for a piston?

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9/6/2017 6:36 PM

Evoracer wrote:

What's considered 'reasonable' hours for a piston?

Depends on the bike and person riding it.

25-30 hours for a 125 and 45-50 for a 250 for a casual rider who doesn't race.

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If you're not mixing gas, you're not haulin ass.

9/6/2017 6:47 PM

Thanks

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9/8/2017 4:01 AM

adam8781, WOW! Thanks for sharing!

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9/8/2017 6:26 PM

KDXGarage wrote:

adam8781, WOW! Thanks for sharing!

That is a double WOW. Was the bottom ate up adam?

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9/9/2017 12:15 AM

Stock yz250 pistons are really bad,
I can not ride it for 20 hours without tearing and splitting apart. I replace the original around 15hours and putr a vertex in, I can ride for 25 hours and it will be very good.

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9/9/2017 12:55 AM

Mixed feelings on the oem yz125 pistons.

Bought my yz125 new from the store, first piston replaced at 20 hours and was planning to run the kit piston for another 20.

However a friend of mine that was running the same bike with an almost similar setup had his locating pin come out at 7 hours. You can imagine the damage with a turning pistonring that gets to know your exhaust port....

So after that i pulled out my oem piston at 8 hours and run vertex ever since then smile

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