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Found 7 results

  1. When it comes to overall strength, there's no beating a forged piston. But what is the process that yields the toughest parts in the racing world? We'll show you. When it comes to turning raw metal alloys into useful things, two processes dominate - casting and forging. Both have their place, but when strength and light weight are priorities, forging is the method of choice. Though it’s been around for more than six millennia, forging processes continue to advance the state of the art, bringing us everything from sharper, more durable kitchen knives to more fuel efficient jet engines, plus things much closer to our heart: lighter, stronger pistons. Although forging is a metalworking process thousands of years old, it’s still the best method to produce components with the highest strength and durability. Forging is defined as the controlled deformation of metal into a desired shape by compressive force. At its most basic, it’s a blacksmith working a piece with a hammer and anvil, and those first metalworkers toiling at their forges discovered something important about the pieces they were crafting – compared to similar objects made from melted and cast metal, they were stronger and more durable. Though they knew the finished product was superior, what those ancient smiths didn’t suspect was that the act of forging was changing the internal grain structure of the metal, aligning it to the direction of force being applied, and making it stronger, more ductile, and giving it higher resistance to impact and fatigue. While a cast metal part will have a homogeneous, random grain structure, forging can intentionally direct that structure in ways that give a finished part the highest structural integrity of any metalworking process. Wiseco forged pistons start as raw bar stock in certified 2618 or 4032 aluminum alloy. Once they’re cut into precisely-sized ‘pucks’ they’re ready to be preheated in preparation for forging. Although many performance enthusiasts might put billet parts at the top of the heap in terms of desirability, the reality is that the billet they are created from doesn't have the same grain properties of a forging. The Wiseco Forging Process Today’s state of the art in forging technology is far removed from the smith’s bellows-stoked fire and anvil. In Wiseco’s ISO 9000-certified forging facility, pistons begin life as certified grade aluminum bar stock, cut to precise lengths to form slugs. The choice of material is critical - conventional wisdom has always said that a forged piston requires additional piston-to-bore clearance to allow for expansion, leading to noise from piston slap until the engine gets up to temperature, but per Wiseco’s Research and Development Manager David Fussner, “Forged pistons do require additional room temperature clearance. However, the 4032 forging alloy we use has about 12% silicon content, and this significantly controls the expansion to nearly the same as a 12% silicon cast piston. The 2618 alloy expands a bit more and does require a bit more room temperature clearance than 4032.” Pistons are forged in a ‘backwards extrusion’ process where a moving punch presses the raw material into the die to form the rough shape. The process takes only a fraction of a second (longer in the isothermal press), and the speed of the press helps determine how material flows, and therefore the internal grain structure of the forging. While 4032 is more dimensionally stable across the typical operating temperature range seen inside an engine, it does give up a small advantage in ductility to 2618, which has a silicon content of less than 0.2 percent. This makes 2618 a better choice for applications where detonation may be an issue, like race engines running high boost or large doses of nitrous oxide. The low silicon alloy’s more forgiving nature in these instances makes up for the tradeoffs in increased wear and shorter service life compared to 4032. Once cut to the proper size, slugs are heated to a predetermined temperature and moved to the forging press itself, which is also maintained at a controlled temperature. There are two different types of presses employed at Wiseco; mechanical and hydraulic. Both have a long history in manufacturing, and each has specific strengths. Mechanical forging presses are well-suited to high production rates, helping to keep the overall cost of high-quality forged components affordable. Hydraulic presses have the advantage of variable speed and force throughout the process, allowing greater control of material flow, which can be used to produced forged components with even more precisely controlled physical properties. Wiseco’s isothermal hydraulic press forging machines use precise digital control of the temperature of the raw material, the punch, and the die, as well as the pressure exerted during the full motion of the forge. This allows very close control over the physical properties of the finished forging. Regardless of the type of press, pistons are forged using a “backwards extrusion” process where the material from the slug flows back and around the descending punch to form the cup-shaped forging. Picture the stationary part of the press (the die) as the mirror image of the piston top, and the punch as the mirror image of the underside. As the punch descends, the puck is transformed into the rough piston shape with material flowing up along the sides of the die and punch to form the skirt. This entire process takes place on the scale of milliseconds (on the mechanical press), and the all-important flow stresses of the material are determined by the strain rate (or speed) and load applied by the press. In addition to three mechanical forge presses, Wiseco also has two isothermal hydraulic presses in-house. These state of the art forges maintain the temperature of the piston slug, the die, and the punch very accurately through computer control, delivering more precise dimensions and geometry for the finished pieces, as well as allowing for more complex designs to be successfully forged, and even the creation of metal matrix composite forgings. Once the puck (left) has been transformed into a forged blank (middle), it still has a ways to go before becoming a completed piston (right). The Heat Is On Once the forging process is complete, the components next move to heat treatment. Wiseco’s aerospace-grade heat treatment facility is located in the same plant as the presses, and here the pistons go through a carefully controlled process of heating and cooling that relieves stress induced during forging, increases the overall strength and ductility of the metal, and provides the desired surface hardness characteristics. While casting can deliver parts straight out of the mold that are very close to their final shape, forgings require a bit more attention in order to get them into shape. Fussner explains, “In a dedicated forging for a specific purpose, the interior of the forging blank is at near-net as it comes off the forging press. And in some cases, we also forge the dome near-net with valve pockets and some other features. Other than these items, most other features do require machining.” Pistons aren't the only thing Wiseco forges and machines in-house. Wiseco clutch are also forged and machined, as well as finished with hard anodizing. The forging (left) allows the basket to closer to the final shape before machining. The basket shown here is just post-machining. One basic forging may serve as the starting point for many different types of finished pistons, unlike castings which are typically unique to a single design or a small group of very similar designs. Regardless of the manufacturing method for the piston blank, some degree of final machining needs to take place to create a finished part. “As a ballpark percentage, I would say about 75% of the forging blank would require machining.” Cast pistons also require finish work on the CNC machine, but this is almost always less extensive than a similar forged piston. “That’s the main reason why forged pistons are more expensive than a cast piston,” Fussner adds. Another reason for the added expense of forging is the significant cost of the initial tooling for the die and punch, which must be made to exact specifications and be durable enough to survive countless forging press cycles. Per Fussner, “We control these costs by making all our forging tooling in house at Wiseco headquarters in Mentor, Ohio.” The ability to make their own tooling, doing their own forging, and their in-house heat treatment facilities make Wiseco the only aftermarket forged piston manufacturer in the United States with these unique capabilities. Once the machining process is complete, Wiseco pistons can also receive a number of different proprietary coatings to fine-tune their performance. These include thermal barriers as well as wear reduction treatments. Though forging is a technique literally as old as the Iron Age, it’s still the undisputed king of manufacturing techniques for light, strong, durable components. Wiseco continues to refine the process with the latest methods, materials, heat treatment, and machining to provide the highest quality aftermarket components available, at an affordable price. Wiseco forged pistons provide superior quality and performance at an affordable price thanks to the company’s close control over every step of the manufacturing process.
  2. stevemcqueen1968

    DR350 issue with valve clearance and decompression

    Hi everyone, I recently got a 1990 DR250 that had the engine swapped from a DR350, presumably 90-93 model. It was missing the decompression lever and cable, and the previous owner used it that way. I put on a decompression lever and cable, then adjusted the valve clearances. My problem seems that either the decompression lever will work and become engaged by the lever, and click back when it hits TDC but with no compression overall, or I have high compression but the decompression lever does nothing. Ive tried to adjust the exhaust valve to the manual spec and even play around with increasing or decreasing the clearance. So it seems either I can kick it with no resistance and no combustion, or nearly impossible to kick but a sputter hear that it wants to start. Am I doing something wrong, or am I missing something?
  3. Hello all... First time here and I hope this is a good area to post this piston head question. I purchased this 2005 KX85 Kawasaki as it wasn't running from the seller, says he couldn't get it started and I've been doing maintenance to it as it was way over do as the carburetor was filthy and the jet were clogged, unclogged clean up carburetor and put back together. So I got around to check the valves from the carburetor side of the piston head looked very good then I removed the bikes pipe and took a photo of the piston head from that end and I noticed a scar or a gouge in the piston head , I really don't think that should look like that. Looking for feedback on what to do next as repait that piton head or can I try to start the bike even thought of this issue with the scar/gouge in the piston head? Any feedback would be helpful. ..
  4. ColeMystrom

    CR250 Compression Loss

    Hey guys, My buddy and I just finished rebuilding his 1998 CR250 which we bought with a broken connecting rod. We replaced the main bearings, crank, gaskets, seals, piston, and the cylinder bored and honed to match the new piston. I did a compression test before it ever started and read about 150 PSI. Then we started it. Ran well, but wanted to die whenever we hit the powerband (this is after we let it idle to break in the seals for twenty minutes) anyway it died a couple times always started right back up until it didn't. I did another compression test and got about 90 PSI. I refuse to believe the rings are stuck, but I guess it is possible. I took the head off and the piston looks fine. Oh also we found some small beads of coolant around the head. I ordered another head gasket (OEM) since I read that the tusk head gaskets don't work great. That won't be here until next week so I thought I'd ask you guys if I'm on the right track in the meantime. Thanks.
  5. Replaced the O-rings and bushing on my front forks of my 2000 Honda CR250R. Got to the step of adding fork oil and did all that but when I pump the piston rod to bleed out air I cant seem to get any pressure for the rod to go back down. It goes down about an inch then stops. Still hear sounds of air pressure in the system possibly but Ive pumped it about a hundred times. Manual says if you cant get pressure youve added too much fluid so ive adjusted it and still no progress. Any ideas on what may be wrong o
  6. Supermotofool

    Low Compression

    Alright TT Gentlemen.. I appreciate any and all who have commented on my posts, without TT and the knowledgeable people in it, things would have taken me much longer. Anyway, I was shimming my valves the other day,before I did it when I checked the clearance.. There was none. I couldnt fit my smallest feeler gauge between any of the valves and the bucket. both on intake and both on exhaust would not fit. I checked my compression before I did this, and it was only at 60/70 PSI which I know is far too low. Before I tear into the engine, I want to get everything I need.. so if A new piston is in store then so be it.. But would valves that have far too little clearance at TDC cause low compression when cranked? Thanks again guys! - Brad
  7. So I got a 2004 crf150f and it has been ticking so I proceeded to do a valve adjustment and it sounded about the same so I let it be and rode it a few times and it was fine but one day as I was riding it started to bog out on the top end (higher rpms) so got it home, checked the valves again and they were in spec. The intake and exhaust both are supposed to be a .004 inch I tried that I was told to try going a .005 on the exhaust to see if that would work I tried a few different ratios and each time they bike would bog out on the top end when I rode it. I’m thinking maybe a valve bent or something so I did a compression test by just kicking it over idk if that’s how u can do these bikes but I got 120 psi I don’t have a manual so idk what it’s supposed to be someone help
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