Forged pistons are harder & contain less silicas for natural lubrication. When a siezure occurs it is much more likely to cause cylinder damage than a cast piston. Plus they need more cylinder clearance than a cast piston, sometimes tough to get in a plated cyl. just my .02
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (MXZ900 @ Sep. 12, 2002, 12:33pm)</td></tr><tr><td id="QUOTE">Forged pistons are harder & contain less silicas for natural lubrication. When a siezure occurs it is much more likely to cause cylinder damage than a cast piston. Plus they need more cylinder clearance than a cast piston, sometimes tough to get in a plated cyl. just my .02[/b][/quote]
Their also lighter, allowing for faster spool to power band revs. This provides an increase in throttle response that will have other people accusing you of jumping the line.
Most OEM applications already provide enough "clearance" to drop in the forged pistons. Even those sledders that are "tight" can usually polish off enough to get within the recommended specs (yes, even with Nickel Silicon Composite).
I always ask the question "why?" whenever I see someone afraid to use Wiseco. It's just a personal thing. I like to know the reasons why people are so against their use.
Every sled in our personal corral use Wiseco. That ranges from a 500 to an 1134cc. Some have over 5 years of pounding the #### out of these engines, some less.
Never a single failure from Wiseco. But you can bet that the initial setup was done right.
It is just my own personal opinion that Piston selection shouldn't be made based on whether or not you may experience scoring a bit more. It shouldn't happen to begin with...
And even if it does, it doesn't take much to wipe out the plating. Most seizures will require a $160.00 recoat either way...
But in the long run, you'll get better performance from the Wisecos...
My ski doo/wiseco experience ranges from stockers to my 97 turbo 670 and i have found that if you use a piston to wall clearance of .005-.006 on 670 and larger motors( bigger the bore the bigger the clearance) the sled will run forever. now with the series 3 engines we dont have the option of opening up the bore a little to get the fit just right, so you either A: count on wiseco to get it right or B: do your homework and hand fit the pistons to the bore. I have found that if you build a rotax with wisecos and it ratlles a little when its cold its going to to be quite reliable as long as you warm the motor up before jumping on it for a wide open blast.
I think another problem is that when Joe six pack changes to Wisecos and does his own "tuning" he goes too lean and siezes the motor. The last thing you want to do is lean down a Wiseco piston. If you run comforable dark brown jetting, you will most likely run a very long time.
Lets see.....You have to use bigger clearences and the wiseco's are more sensative to lean jetting. I think I'll stick to cast pistons. There are ways to make cast pistons lighter. A well respected local tuner has been doing it for years. I've never seen him use Wiseco pistons. Bigger clearances and richer jetting are just a bandaid for the real problem. The piston itself. Just my opinion of course.
I had poor results with Wiseco pistons in the late 70s and early eightys. Runningsuch loose cylinder to wall clearences caused the piston to slap and knock out the ring locating pins, not good. My recent experience on smaller two stoke, dirt bike 250cc has been the wisco pistons are running .0015" clearance. Did they change the metallurgy, More silica maybe?
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