I know a lot of people that puts Namuras on they´re 4 strokes and ride hard (national champ. riders), no problem.
On 2 strokes i hadn´t been very lucky. on a cr 125 the piston doesn´t hold up very well, like a vertex, with a semi weared bore. on a yz 250 the piston just explode himself after a few running hours with no apparent reason besides the skirt is thinner than my cr80 piston. It seems more brittle than other pistons for the same bike as well.
By no means i am no expert but some friends that do own maintenance on they´re bikes hasn´t been lucky as well. :cool: