Was wondering if people who have tried going to an 80mm overbore (280 kit) have experienced any problems? Reading some of the posts, Rick Peterson seems emphatic that the bores will go out of round at this size after 20 hrs of use or so depending how hard pushed. Anybody experience this? How about rod/bearing failures from the increased piston weight? Overheating problems? Also, when going overbore, can a cylinder from an '04 or newer be used? These have the cutouts. I'm wondering if you can only go +2mm (262cc) on the cylinders with the cutouts or if the cylinders with the cutouts should not be bored at all and you need to get the older type cylinder if you want to bore it. I'm guessing that when they design the cylinder it has enough margin that you can go 2mm over without a problem and thats why so many outfits offer the 262 kit. Going 3mm might be pushing it but it would be nice if you could get away with it. Both Vertex & Wiseco have pistons available. Cost would be the same between the two. Also, what sort of jetting changes are required. I've had a few people tell me none but seems to me that if you up the displacement and make more power you need more fuel in there and a bigger main jet to deliver it. Wonder if this is why some are reporting loss of top end, if they are not jetted rich enough. Thanks for any feedback. I'm going to try this over the winter and need to decide 262/280. I don't want to lose the topend rush my '05 yzf250 has but would be happy if it got stronger everywhere.