72cc slower than stock 50cc???

[alwaysright]

I put the 72cc kit in my roketa bahama scooter this weekend and it's still slower than my buddies 50cc roketa maui. Have similar miles around 130. and his was way faster, now just a little faster. I've gone from 32 MPH to 38 MPH on gps. What am I doing wrong. vavles are right on, but just doesn't have the same top end, seems wierd. I've got the 6.5 rollers, 88 jet, and no rev limit cdi box. My kit didn't come with a cam and I'm putting that it next weekend but also wonder how much I can gain from a cam, maybe 1 mph is what I was thinking. any help would be appreciated.

 

[Vspeed]

6,5 sounds way to big in my opinion,
i guess you should try 5gr or less, maybe even 4gr
and what size of carburator do u have?
standard 12mm?
Cuz if so, your cillinder might not get enough fuell,
If u go bigger in cillinder capicity,
You have to go bigger in everything like
Crank,
Carburator,
etc