gearing and clutches

[87 banshee]

Well I just put my 87 motor on a 2001 frame what a diffrents I think. I have a 14 tooth front sprocket and a 39 back sprocket but I am still running through 6th gear to fast I thought it would be way to much but rideing it it isn't. whats a good gear. It will still pull the front up in 4th. The other thing is i have new barnett clutches but seems to sleep once in a while i was told to put 80 90 weight oil in it any ideas.