if i put a bigger sprocket on the front of my dirtbike will its make it faster or slower or sould i just use?

Question

a stock 13t instead of the new 15tooth its built for motocross racin it got a big bore kit with a HMF Exhaust on it is a honda xr250 its all racing nothing stock but the frame and plastic

Answer 1

You will raise the gearing significantly with a 13 if standard is 15. This will give you less low-end torque, but, as the last writer said, a higher top speed (assuming your bike has the power to exploit the gearing). This might be appropriate if you do a lot of road miles.

You are best off to ride the bike on its stock gearing and see if you are happy: is the off-the-line acceleration good enough? Are you constantly revving the hell out of it in the higher gears? These are the symptoms that tell you you need to change the gearing.

One tooth change on the front will equal approximately three-four teeth on the rear sprocket (ie, 13/53 will give you the same gearing as approximately 14/49). Another way to look at it is, if you raise the gearing by one tooth on the front, you have thrown away first gear but added an additional, higher gear to the gearbox.

Answer 2

A larger front sprocket on the chain drive will give you a higher top end, however it will take you longer to get up to that top speed because the engine has to work harder. Consider this thought... how often do you ever really get to top speed on a dirt bike? usually if you ride on a track you are not to often in top gear anyway... i would go with a larger rear sprocket and a smaller front sprocket. that way your "launch" time is much faster. i ride on a track all summer long and i really love being able to tear out of corners and rip up to jumps really quick. Personaly i think you should enjoy your bike for what it is... a 250(wich is a pretty powerful ride), if more speed is what you are after than consider selling your bike and getting a XR500.

Answer 3

A bigger front sprocket will give you a higher top speed but slower acceleration and less hill climbing ability due to less torque produced at the rear wheel.