FireHead

I was talking about pistons..............nothing else. What would you rather have, a piston that expanded and contracted less, but changed shape and did it differently every time, or a piston that expanded and contracted more, but did it the same every time? This is why a forged pisston is better and why you don't see too many folks running cast pistons in a mission critical application. :ohmy:

Silicon content can be the exact same between a forged and cast piston. Due to alloying processes and forging techniques the generality of a cast piston having a higher silicon content than a forged piston is no longer true. If I were to pull a decade out of my butt, I would say it hasn't been true since the 1950's.

You are correct. This is the message I have been trying to get across. I was beginning to think I was retarded or something. :biggrin:

First off, the silicon content of a cast piston vs. a forged piston can be the same or different. There is no rule of thumb there. Just because a piston is cast does not automatically mean it has more silicon in it, that is just BS. A cast piston is not more dimensionally stable! Forged pistons have a higher overall max and min value for growth on the o.d. of the piston during a heat cycle. A cast piston will actually change shape during a heat cycle, not just expand and contract. I am afraid that you keep referencing generalities that are well over thirty years old and are out dated. A word of caution when speaking to a builder about pistons. Please make sure you have read atleast enough on the subject you are asking the builder about to spot some verbal poo. I have heard some pretty strange things (second or third hand of course) on here that people said a builder told them. At the end of the day a builder is going to tell you what he has had the most success with. Right or wrong, that's what works for him. :thumbsup:

That is near the top of my list of best piston failures from an ATV.

The guy seems ok when I have talked to him, but I never bought anything from him. I think the divorce story is legit as well are all of his personal problems that go with it. I suspect you don't have an arm because he hasn't been able to get one made for you. The moral of the story is that he should not have taken your moeny if delivering an arm wasn't a sure thing. I'll verbally whack him with a stick if me gets ahold of me again.

No, I really don't have them backwards. I am not really sure how to offer a non-metrological explanantion for this, but I will give it a shot. First we must make a few assumptions / state a couple of general rules. 1.) A cast piston requires a bore that is not as large as would be required for a forged piston of the same size. 2.)The cast piston is made via a vacuum degassed die casting process (there are several processed out there, this is the most commonfor this genre of discussion) 3.) Post casting turning is done with a relatively simple cam turning setup on en engine lathe. 4.)The engine creates a eutopian heat cycle profile for the piston (not really possible, but it keeps a lid on a can of worms). 5.)The cast piston is made of a 4000 series, 5000 series, or tenzalloy material. 6.)All pistons go through a proper stress relieving process. All that said a cast piston will change shape much less uniformally during a heating cycle than a forged piston. A forged piston may expand and contract more than a cast piston, but it does it in a uniform nature. This is what is important to someone developing a race engine. As long as the gorwth is consistant and repeatable, it really doesn't matter how much it changes dimensionally. Thus, in the spirit of racing engine development, a forged piston is always better (there are exceptions to this, but they are a whole other topic). A cast piston may expand and contract less from a general outside diameter, but along the entire outside diameter the gradient of change is ver inconsistant when compared to it's forged counterpart. This is due to elements of the metal alloy concentrating in certain areas as opposed to staying evenly blended. In lamens terms like elements like to hang out with each other as opposed to staying evenly mixed in the crowd (I know that was corny, but it could have been racist too). I am sure someone is going to mention grain structure of the material, but with a piston, it doesn't matter within reason. All of this is a generally know stumbling block with casting. I am sure I need to put more into this post, but I am tired and typing doesn't seem fun right now. Please point out what doesn't make sense I will be happy to explain and/or repair it. I hate to do this as it generally annoys me when people do it to me, but I have spent more time than I would like to talk about designing, machining, developing, race engine parts. Pistons are a big deal past a certain point, as are engine blocks, and crankshafts. I am sure the time I spent hacking aways at several piston issues will boggle my mind if I were to keep track of it. On top of that, I would like to note that piston manufacturing is a weird business. Compare and contrast, JE, Mahle, Arias, and CP...............none of them use exactly the same process for anything. CP and JE are particularly entertaining. IF anyone is really interested in this stuff, JE has an open house at their facility in SoCal. It's worth the time to go on if you are an engine geek. It will definitely make you say "what the hell?" more than once. Think about all of the operations, QC, fixtures, deburring, and programming that is required to make a family of bore sizes for one engine. Multiply that by all the applications they make pistons for...............................................and like I said you will say "what the hell?," all that work for a price competitive product that usually has nothing more to differentiate itself from a competitor than it's brand name.

Louis at Twister is awesome....................and now he is just ride down the road from me.

Dan at Patriot would be my 1st choice if you didn't want to ship your parts. I have heard Dan has been off the radar lately. I am not sure if there is any trith to that.

WHoever made that needs to sign up for voluntrary neutering.

Nope not really. An aluminum casting will always expand more unevenly than a forging..............not sure how you could think otherwise.

Yes, it was you I was referring to. LoL

I think I am just damned...........

Alright, I have to throw a couple of rocks back at ya here: 1.) A piston that is made from a casting is not more brittle, nor than a forged piston. Simple strength of materials stuff. The universal " no free lunch" rule applies here. A cast piston generally is less dense than a forged piston material. With aluminum, lower density you ge maleability. I would venture to say that piston cracking might be more common with a cast piston, but it's not because it brittle. I would say that it is because you generally cannot achieve the same sectional thickness with a casting as you can with a forging. 2.) Cast pistons exist for and have existed for a long time for several reasons. The classic scenario is that it used to be the better way to make a piston as forging and machining equipment used to not be the as they are today. I would venture to say that this was the case up until the 1970's (I pulled that decade out of my butt). Now, if you are mass producing a piston in a volume similair to that of bullets, then it is cheaper to cast them. A vacuum degassed cast piston used to be a better piston type than a forging, when forgings were just a mechanically smashed piece of aluminum, but that simply isn;t the case any more. Now, in 99% percent of piston design scenarios, you look towards casting as being the less expensive option for mass production if you can make the rest of your engine suit that choice. 3.) Tighter tolerances seems to be used as a blanket term here. If you are talking about the piston itself, then a forging is always more dimensionally stable than a casting. If were are talking about bore tolerances, then they need to be of a higher tolerance for a forging. 4.) The higher silicon content of a cast piston is bogus. With the current state of material technology, you can have a wide range of alloy material in either piston construction type. That arguement is about 30 years older than I am. Ok, past all of that, both piston design have there place in many industries. I am also not interested in starting a piston contstruction pissing match. I tend to go a bit overboard when speaking on this subject, but please keep in mind that when I am saying a forged piston is always better, I am speaking to a higher performance engine application. Which is still slightly BS as it's only true in 99.8% of such applications. It really all depends on what you are trying to do with an engine. As Brad says, if you have an OEM set of cylinders on a Banshee and simply have bolt on stuff, then go get Jim-Bob at the local Napa to bore your cylinders and throw a set of Pro-X pistons in there. That makes the most sense.

Who knows.........I know the owner and have a few things from them over the years. When they were first getting started and only had a few leaky old Haas machines I did a bit of programming for them to help out (I was still in school). Dependin on when you bought the stuff, may be it was one of my programs that made it, in which case ha ha (Nelson's laugh from the Simpson's). :biggrin:

http://cgi.ebay.com/ebaymotors/yamaha-bans...1QQcmdZViewItem Saw 'em. Thought somebody might need them. :biggrin:

European pistons you are thinking of are probably made by Mahle. The coating I am sure is made by Balzers. Beyond that, I had a crappy day at work and do not feel like getting in a forged vs. cast piston arguement. If RNBrad wasn't such a nice guy, I would probably get up on my soap box a bit more. Pistons made from a forging are always better if your cylinder bores are machine correctly to accept them. If you do not do any machine work and are looking to throw pistons in a bike engine that had OEM cast pistons, then you need to put cast pistons back in there. If you do shitty machine work, then, again, cast pistons are your friends as they are more forgiving. If you put value in reliability and performance, then a quality forged condtruction or billet CNC machined piston is the only way to go. I am sure someone will dig up an internet article to contradict me, but if you really need to do that, you may also feel free to send me a PM containing your favorite vehicle magazine and I will figure out a way to get an article authored by me or atleast written on the subject using me as a noted reference, published......................I apparently have that kind of free time on my hands. :ohmy:

I haven't heaqrd of that happening before. Can you post a pic of what you are fighting with? I think that is going to be the best way to get help from me. Maybe one of these other guys with more experience can help without pics. Your name on here makes me giggle out loud, by the way.

I thought that looked like the Expo center in the background. If I didn't have my blue bike project going, I would be all over that frame. I would guess that the asking price is relatively fair. :smile:

If I ever brought something like that to the track, I would have been fired. :geek:

When you spend $4k on a frame, I think you are allowed to take it and have it repowder coated. That's baller? :ermm: I can't really pull that line off.

That is a nice cap............all the Mod Quad stuff is nice. I am pretty familiar with the programming of a bit of their earlier productline.

That sounds like a metaphor for wiping after you poop. :geek:

That is a nice frame. I remember seeing it when it had the triple in it before it was moved to an HS Customs frame. I wish I was rich.........I 'd buy the hell out of that thing. :thumbsup:

The Maxima and PJ1 spray wax I used to use performed great. I have since tried the WD40 thing on reccomendation from a few key folks on here, and I do not believe I will ever go back to the wax. :geek: