I have just bought a yfz 450 and on tack it is mint but i have just got it road reg and took it out on saturday but on the road you are in top stight away and it reving its self to bits at about 50-60 mph any onr have any ideas on how to improve this without spoling its off road pull. my brother raptor sems to be ok on the road

 

I'm guessing you're not from the states....
I'd say put some street slicks on it, take off the air box lid, Pipe it, jet it, and let 'er rip.

 

i have already piped, jetted and took box off still not fast enough

 

If you want more top end speed either change your gearing (ideal solution) or go with an aftermarket cdi box so you're rev limit is raised. But you run the risk of damaging the motor by doing that. The adverse affect of changing gearing is you will loose some low end punch also.