cast vs forged pistons

Discussion in '2-Stroke Discussion' started by expansion chamber, Apr 5, 2010.



  1. expansion chamber

    expansion chamber Rookie DRN Member

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    Cast are lighter, forged are heavier. Which is better? I have a bored out yz 250 and have a wiseco in there now but have always been a fan of Pro-x pistons. Im going to continue with the wiseco for awhile longer but was considering getting a pro x one next and was just curious what you guys have ran into for expirence with both.

  2. Rich Rohrich

    Rich Rohrich BioHazard

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    Not necessarily.

    Define "better" in this case.
  3. whenfoxforks-ruled

    whenfoxforks-ruled Old MX Racer

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    The pro x? Isn't that the cheaper product line, offered by Wiseco? The cast is worth 50 dollars less than the forged, Wiseco said so! How on Earth can their cast be "better" than their forged? You do get what you pay for, generally. Vintage Bob
  4. RM_guy

    RM_guy Scared of DirtWeek<BR>Club ********* Damn Yankees

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    Do a search. There is tons of info on this topic.
  5. expansion chamber

    expansion chamber Rookie DRN Member

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    I was referring to better as in, is cast more reliable than forged? do forged pistons offer more performance? visa versa. what else would someone ask for? looks? no. Ive ran both kinds of pistons. Ive used more Pro-X pistons than Wiseco and had good luck with Prox.. I was just asking for other peoples expirence on using the two different types of pistons.

    I have a little over 30 hours of time on the wiseco and the skirt coating is all worn off.

    I run SPI cast pistons on my 700RMK sled, they are ceramic coated and they seem to hold up really well for having over 150 hours on them. Seems like the forged pistons dont hold the coating as well as the cast pistons. IMO
    Last edited: Apr 5, 2010
  6. whenfoxforks-ruled

    whenfoxforks-ruled Old MX Racer

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    You are complaining that you only got 3 times the life out of a piston? How many re-rings went on it? I am not in the kdx forum again? Vintage Bob
  7. expansion chamber

    expansion chamber Rookie DRN Member

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    I never re-ringed the wiseco piston. Ive ran my yz when it was stock with stock piston in it for 3 years before rebuilding it. And I put alot of time on the engine each year.
  8. expansion chamber

    expansion chamber Rookie DRN Member

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    You misunderstood me. I have ran more Pro X pistons in my life time than Wiseco. Im trying out wiseco a little more to see how they compare to Pro X. Shouting out for some friendly knowledge about other personal expirence with them and Im just getting questioned.
  9. whenfoxforks-ruled

    whenfoxforks-ruled Old MX Racer

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    I never hit the capitol or entry keys hard? I was just clarifying something. If you can run a piston that long, you could run probably any piston made. A lot can be said for air filter maintenance, and how heavy handed you are, for it to last that long. And I would be real watchful of the bore staying true. Sleeve or coated bore? What were the skirt and ring gaps? I have heard all kinds of long stories on my 480, but around 10 hours the top ends coming off to see how its wearing, and put new rings in her. Vintage Bob
  10. _JOE_

    _JOE_ Subscriber

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    I've always used Wiseco. I've never run one more than around 75 hours or so. The 250f is my first bike that really shows any skirt wear after 30 or so. The wear on the skirt is allowing the piston to rock in the bore and can lead to the skirt cracking and breaking off as well as an ovaled bore. But at least the broken piston will do enough damage you'll need to oversize the bore anyway......

    I know several guys who run Pro-X with good results as well. They all take good care of thier bikes though.
  11. plynn41

    plynn41 Rookie DRN Member

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    Hey,
    Don't know about the YZ hardware, but there seems to be a consensus with CR500 riders (cr500riders.com and bannedcr500riders.com) that Pro-X pistons are to be avoided due to poor architecture--the sides of the pistons are open to the exhaust port, allowing the transfer charge to blow straight out when the exhaust port should be sealed. Also, alot of those guys are getting away from Wiseco forged pistons because they seem to seize easier--the forged aluminum is apparently stickier than cast.
    That's why I'm putting a Vertex cast piston in my '85 CR500. All reports I have gotten is that reliability is similar to OEM.
    Hope this helps!
  12. whenfoxforks-ruled

    whenfoxforks-ruled Old MX Racer

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    Geez, are we going down the crapper? What next, testimonials for namura and magnum brands? Forged are Stickier, really? And to think of the money I could have saved, never changing my oil in a car with over 200,000 miles on it???? Is that a sign of quality, or dumb luck? I would rather believe its how the engine is getting used/abused. Doing a search seemingly did not work, we will now roll over and be another hear say site? Anybody else up for hear say talk, or dig up the facts, forged are miles better than cast. Stickier? Some new engineering word? Vintage Bob
  13. ellandoh

    ellandoh dismount art student Mi. Trail Riders

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  14. holeshot

    holeshot Crazy Russian

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    Forged pistons are generally used in high perfromance applications because of their greater strength over cast The grain structure of forged metal tends to follow the shape of the piston (because it was hammered into shape) and the cast grain structure follows one line. Forged pistons expand more than cast when heated, so they need slightly looser tolerances when cold (which can cause the forged piston to rattle a bit more at start up).

    Regardless of which method is used, it still depends on the manufacturer to create a quality product and the installer to intall it correctly.
  15. plynn41

    plynn41 Rookie DRN Member

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    Did you have a bad Easter weekend Bob?
    If my comments aren't useful, then disregard them.
  16. RM_guy

    RM_guy Scared of DirtWeek<BR>Club ********* Damn Yankees

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  17. expansion chamber

    expansion chamber Rookie DRN Member

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    but does a harder piston (forged) wear the nikasil coating quicker than a cast piston?
  18. whenfoxforks-ruled

    whenfoxforks-ruled Old MX Racer

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    I highly doubt an aluminum piston, whatever can be done to it, could EVER wear a harder plating out. Running a loose piston has the effect of pushing the material behind the plating out of round. I doubt it would on a sleeve though, thats why I asked. Loose a bearing, ring or cir clip and say good bye to the bore. Most of the seemingly horrible looking bores, thats just aluminum flashing rubbed onto the plating. A scotch brite pad and oven cleaner takes it right off, back to the original hash mark. If a guy wants to run long, put the sleeve in, they even claim to have chrome and some alloy sleeves, and they can plate sleeves. Only 1 issue, they still wear quicker than oem or better plated aluminum. The heat dissipation and expanding and contracting differences. 3 races or 7.5 hours, thats what my 97 CR250 suggests. I know darn good and well that I can go longer, minus any debris catastrophes getting by the carb. I also know that James Stewart could NEVER get that much time out of a top end. His would do well to last 30 minutes plus 2 laps. Wiseco, namura, vertex what ever, they are not going to tell you much longer than the manual. 5 to 10 hours on a 250, the rings are gone, less for the smaller bores. And that is running 32 to 20:1 premix ratios! My recent experience with used dirt bikes has pushed the limit on what gets said about how long parts last Plynn 41, proper maintenance and these bikes would last a lot longer, and be a lot cheaper in the long run. Abusing the maintenance schedules, I sure do not want to buy a bike from someone like this again! Not too many 2 stroke ex-racer bikes around anymore. Vintage Bob
  19. RM_guy

    RM_guy Scared of DirtWeek<BR>Club ********* Damn Yankees

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    Whether it's a forged or cast piston it's going to wear the same. They are both aluminium and one is not harder...or softer than the other. They both will wear out long before the plating.
  20. In come tacks

    In come tacks Rookie DRN Member

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    Seems like the forged doesn't grenade, and I hate installing crankshafts! I think the one guy had it right, if you're not changing your cast piston after every hard long run, then forged would last longer.
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