Midway USA Posted April 6, 2009 Report Posted April 6, 2009 Got a box of used parts the other day and there is a pair of these pistons for a Banshee. As seen in the picture the ports in the piston are higher. The top edge on the exhaust side is notched out. It has 3889K stamped toward the edge. Has 9440 and 64.42mm stamped in the middle. What are these? What do they fit? Stroker? Long rod? Quote
trex banshee Posted April 6, 2009 Report Posted April 6, 2009 I believe those are vitos pistons. They are for stock rod length. The exhaust side of the piston is stepped down to simulate a ported cylinder. It makes the exhaust port open sooner than with a normal piston but still keeping the transfer openings at the same time, this increases your blow down time. Quote
spike Posted April 6, 2009 Report Posted April 6, 2009 there Vito's superstock pistons, there made for stock stroke, stock porting engines. the intake windows and top cutaways are meant to mimic porting by changing port timings. I dont know if they work well but vitos claim 8hp gain across the board. I don't beleive it will give that much gain but probly help a bit i guess. here a review I found on them. http://www.atvsource.com/articles/product_...ock_pistons.htm Quote
Midway USA Posted April 6, 2009 Author Report Posted April 6, 2009 (edited) there Vito's superstock pistons, there made for stock stroke, stock porting engines. the intake windows and top cutaways are meant to mimic porting by changing port timings. I dont know if they work well but vitos claim 8hp gain across the board. I don't beleive it will give that much gain but probly help a bit i guess. here a review I found on them. http://www.atvsource.com/articles/product_...ock_pistons.htm Cool. Thanks. I think I will keep them around for spares. Buying some standard bore jugs for spares and may try these pistons out some time. At least they are made by Wiseco. What the hell overbore is .42mm? I work in a machine shop and we bore and hone these jugs all the time and I have never seen that. I assume that would be .015 or somewhere in that area? Just looked for rings and .50mm is as close as it gets. That works out to .003 so I assume you could use a ring file and get the correct end gap? We've done that on some odd car applications but never on a motorcycle. Edited April 6, 2009 by Midway USA Quote
TJScott Posted April 6, 2009 Report Posted April 6, 2009 they arent made by wiseco. how come it always seems that one piston is alot dirtier than ther other? Quote
03bansheeLE Posted April 6, 2009 Report Posted April 6, 2009 Those are Vito's Super Stock Pistons and they are made by Wiseco to Vito's Specs. There should be a stamping under the crown of the piston that says "Vito's". These pistons preform significantly better than stock pistons. I suppose if you dont want to port your engine but just want to put new pistons in then these are the ones to use, I had them in my bike and it pulled much harder mid to top end than stock pistons and actually seemed slightly better in the bottom end too. You cannot get these pistons for stroker and/or long rod engines. Quote
Midway USA Posted April 6, 2009 Author Report Posted April 6, 2009 (edited) how come it always seems that one piston is alot dirtier than ther other? The other piston in the pic is a std stock one just for comparison purposes. One of these Vito's is almost clean on top and the other is totally black. They seem to be in good shape otherwise. I'm going to take them to work tomorrow and clean them up and measure them. Might be worth a try for free and the price of rings. I also got an upper end gasket kit with the parts so not a bad deal. Edited April 6, 2009 by Midway USA Quote
TJScott Posted April 6, 2009 Report Posted April 6, 2009 The other piston in the pic is a std stock one just for comparison purposes. One of these Vito's is almost clean on top and the other is totally black. They seem to be in good shape otherwise. I'm going to take them to work tomorrow and clean them up and measure them. Might be worth a try for free and the price of rings. I also got an upper end gasket kit with the parts so not a bad deal. oh, i was just wondering if this was common since my vito's pistons were the same way, but my wisecos werent. Quote
Midway USA Posted April 6, 2009 Author Report Posted April 6, 2009 oh, i was just wondering if this was common since my vito's pistons were the same way, but my wisecos werent. My regular Wiseco pistons have always been relatively clean on top both cylinders. Quote
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