at 58 mph is your scoot getting unstable ? squirrelly?
changing springs or dr.pulley's isn't going to lower
the rpms your motor makes.
all that stuff is down the line in the power train from the motor.
so for now be easy with the throttle and stay away from WOT.
usually the speedo is inaccurate on speed on most scooters..
especially at higher speeds, and the higher you go the more
inaccurate it reads.. at least thats the old cable & dial style.
also your motor will get hotter with more rpms so the plug color
is very important to know your not too lean!!!!
and the heat range of plug is important might be a good idea
to go with a cooler 8 or a 9 ~br8hs if you have a 70cc or if stock cylinder
bpr8hs.
heat kills !!!!!!
btw; there are adjustable cdi's like this
http://whidbeyislandmoped.com/cart/index.php?main_page=product_info&cPath=17&products_id=240the blue square has a tiny screw for adjustment.
you could dial it down to 10,500 rpm
remember when i told you about changing the gear ratio?
that is really the best way to get more speed from your slightly
moded motor.
a variator with a bigger diameter would do it too if there is one
for the tgbs
anyway you should ask your mechanic these questions since your paying
him to do your work ,if he's any good he should know this stuff.
oilyhans