400ex sprokets on a 250x?

[bigred50]

I have a 250x that is bored and stroked to 370cc's and I need more top speed. I have it geared twards speed as much as I can with 300 ex sprokets but 1st and second gear are still useless. So will 400ex sprokets bolt right on to my bike? Thanks for the advise

[born2ride14]

front or rear sprocket?

[bigred50]

Umm will either fit? Rear would be better though

[born2ride14]

rear sprocket should fit

[bigred50]

Ok I'll try a new rear one thanks!