Can a KX450F '08 transmission fit in an '06 crank case?

[CaocaoWR]

I have a friend who is getting tired of his '06 4gears transmission and would like to have 5gears like the '08 KX. Is there anybody make a switch to the transmission like that before? Would love to hear some advice. Thanks!

[stlavsa]

Id find and '07 or '08 motor and swap it in

[numroe]

No chance. There are lots of little differences inside those two cases.

If your friend is trail riding, the get an 08 engine. Or just put 13:48 gearing on the 06 and it'll go plenty fast in 4th.

If he is riding MX tracks, then 5th gear is useless anyway.

[CaocaoWR]

Thank you!

He has two crank cases with a top end, and he wants to make full use of them. But it's seems impossible.

So if he wants to do trail riding the only & easy option is changing sprockets.