Sprocket specialists here in the US has just about everything and if they don't they can make it. Andy is right though things get really tight with a 16 but I've been running one for some time now with no problems.
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1995 A kit TZ 250
1994 Rothmans NSR 300sp SOLD
1998 RM 250 freestyle/motorcross
1998 Meathanol burning CR 500 AF super retard/motorcross/sand dunes/play bike