Forged v Cast pistons

[Old Git Racing]

Anyone give me some pros and cons of forged v cast pistons in a 2 stroke?

OGR
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2022 Tiger Sport 660 2019 Street Twin 2003 K3 gixxer 1000 1998 Srad 600 track hack

[Nexus Icon]

Forged are stronger. Cast are cheaper.

That's pretty much it, tbh.

Forged pistons have an irregular grain structure, which makes them more strong in all directions. Cast pistons have a regular grain structure meaning they will have inherent weakness and stress raisers.

Forged parts are formed using immense pressure to push the red-hot metal into the desired form. Cast parts are moulded using molten metal.
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Greetings from Shitsville!

[Willson]

Cast means that molten metal has been poured into a dye and allowed to set.

Forged means that red hot metal has been bashed into shape. Therefore, stronger and much heavier.
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Benson: Wouldn't life be easier if we were all turtles?
Me: Pig on bread = The way forward.
Riding: '00 Suzuki SV650S. Previous: '99 Kawasaki ER5 - sold, '02 Suzuki GZ125 Marauder - sold

[Nexus Icon]

Well, I dunno about them being heavier. That rather depends on whether they're made out of the same material. Forging and casting doesn't drastically alter the density of the material, only the way the grain structure lines up in the part.
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Greetings from Shitsville!

[Willson]

Forged metal is denser, you've essentially pushed more metal into the same amount of space.
Edit: Forging removes most irregularities and voids that can be left behind by casting.

If they're the same metal then yes the forged version would be heavier.
____________________
Benson: Wouldn't life be easier if we were all turtles?
Me: Pig on bread = The way forward.
Riding: '00 Suzuki SV650S. Previous: '99 Kawasaki ER5 - sold, '02 Suzuki GZ125 Marauder - sold

[Nexus Icon]

Hmmmm, only if it's a sh*t piece of casting. There shouldn't be any voids, Willson.
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[Frost]

Denser material doesn't mean the piston is heavier. It being denser and stronger means less material will be used therefore making it lighter.

[MarJay]

[Glenben92]

[MarJay]

[MarJay]

If I can get back on topic a bit:

I can't honestly see the point in forged pistons in a 350 powervalve unless you plan to fit Banshee tuning stuff to it. I can't think that you'll see any benefit of using forged pistons until you get the thing up to 100bhp+

I suspect this is probably a question for Stan Stephens rather than us lot though. Collectively we know a bit, but he's probably forgotten more than we'll ever know.
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[Old Git Racing]

Thanks for the replies

Have already got the pistons. They are going in a tuned YPVS, nothing like 100bhp though. Having had pistons fail before it sounds like these will be more durable if not a little OTT.

Thanks,

OGR
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2022 Tiger Sport 660 2019 Street Twin 2003 K3 gixxer 1000 1998 Srad 600 track hack

[Frost]

Surely having lighter pistons is a part of getting extra power out of the engine?

[MarJay]

[CaPo]

I dunno about 2 strokes, but a disadvantage of forged pistons on cars is they need to fit slightly loose when cold as they expand more than cast. This means slightly reduced compression, more oil burning and poor running on cold starts. Fine once warmed up though.
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