JT Front Sprocket Yamaha YZ 250 99-.. YZ/WR 400/426/450 F 98-.. Kawasaki KX 250 99-08

Before taking a final decision while selecting a certain front or rear sprocket, we have to bear the following premises in mind: 

• The higher the number of teeth on your rear sprocket, the shorter the development. Therefore, our dirt bike will improve  the delivery of power to low regime, but it will lose top speed.

• The higher the number of teeth in our front sprocket, the longer the development. Our dirt bike will lose delivery power at low speed, while gaining top speed.

• The lower the number of teeth in our rear sprocket, the longer the development. Therefore, our bike will lose delivery power at low speed, while gaining top speed.

• The lower the number of teeth in our front sprocket, the shorter the development. Our bike will gain delivery power at low speed, while losing top speed.

• ATENTION: If we decide to vary the number of teeth in our front sprocket, the change will be more noticeable than if we were to do so for our rear sprocket. One tooth difference in our front sprocket, equals the change of three teeth in our rear sprocket.

• Therefore,  if we want to slightly modify our dirt bike performance, the ideal way to do so would be to increase or decrease one or two teeth in our rear sprocket. Contrariwise, if we want a more noticeable change in the performance, we can choose to increase or decrease the number of teeth on our front sprocket one by one or do the same for the rear sprocket but always changing the teeth on a  3 by 3 basis.

• IMPORTANT:  every time we decide to modify our dirt bike´s development, we must be extremely cautious not to set an excessively small or large rear or front sprocket up. Such detail could cause the chain to apply excessive forcé onto the chain slider or the chain guide, potentially causing a premature attrition of the latter.

• Please, bear in mind that every element of transmission must have a simultaneous wear.  It is not advisable to install new crowns and sprockets with worn chains, or new chains with worn crowns and sprockets. The duration and resistance of such components will be severely reduced.

• Last but not least: If you were to change your rear sprocket, do not forget to use a screw fixer and give the nuts the proper tightening torque, always in cross fashion.