You must use a tapered style sprocket bolt (part #1096010001) for this sprocket to work on a Yamaha WR250R.
Sprocket kits include the following.
Stock size Primary Drive steel front sprocket.
Stock size Primary Drive Alloy rear sprocket.
Stock size Primary Drive X-Ring chain.
Front sprockets are manufactured to O.E.M., specs using high grade hardened steel.
Rear Aluminum Sprocket made from 7075 T-6 heat treated Aluminum.
Come with self-cleaning grooves.
All match original equipment exactly for perfect fit and size.
The ORH X-Ring chain is Primary Drives best off-road chain for performance and durability.
X-Ring shape provides an outstanding seal with reduced friction.
Average tensile strength 8,120 lbs.
Always verify chain length currently or previously in use. Gearing adjustments may require chain length adjustments. Use Tusk HD Chain Breaker #1389240001.