That sounds odd. Are these Wossner pistons made for the nsr250, or are they RM125 pistons that 'fit', or something else? You'd think if they were made specifically for the NSR they'd be the right height and have the ring clip positions sorted...
If I could run Wossner pistons in my NSR300, I would. They look very nice and very light. Would trust them over the Weisco forged jobs. Then again, I have ART pistons or some such in it atm :S
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MC21 Honda NSR250. TYGA 300 conversion.