These bikes seem to vary a lot in performance when delivered. Some have significantly
lower top speeds. You have to figure out if it's in the trans or engine. Swapping from a
known good one should help! The trans consists of the variator, the rollers, the belt and
the clutch assembly.
Things affecting takeoff speed are the clutch springs and pads. I found the one's on my
Yager have antirattle dots under them that are extremely tight, that would slow the
engagement of the pads. Aftermarket springs are generally stronger to give a higher
RPM for clutch lock and you need weaker...
The variator face has a shape and can speedup and slowdown the RPM's as you accelerate.
My old Aprilia 500 would hold one RPM all the way to the top of the variator. The Yager is
all over the place so I wouls expect it is nonlinear.
If you swap the variator you must also swap the contra spring. This is the spring behind the
clutch. I noticed I could compress mine by hand at first but when I reassembled it I couldn't.
A weak contra spring will loose speed on hills, a strong one will need higher RPM's to shift up
(the same as lighter rollers).
Mine tops out at 60 MPH so I've been trying to see if some component is defective as it is
a 170cc! I still haven't come to any conclusions.. I hope this helps!
