acceleration flat spot 30-40km/h?

[razmoo]

my scooter accelerates very slowly between 30-40km/h, like this guy's problem:

forum.scooterforum.net/forum/f95/acceleration-rollers-help-160267/

if you don't want to click on the link, someone replied saying:

"You need a harder contra spring, because as your spring is too soft, it doesn't close the pulley all the way in, missing low revs."

is this correct? and thats what i need?

am using 5.5g rollers, and 2000 rpm clutch springs atm.
i found 4g too light, it seemed to rev a LOT without moving too much.

[jmkjr72]

yeah i had the same issue when i was first starting with my zuma
and i replaced the varatior with the stage 6 and it came with a stiffer contra spring

[razmoo]

ill try a lighter roller than 5.5 (but heavier than 4) first as thats the easiest to do, and then try to change the contra spring.

will let you know how it goes. thanks.

[reveeen]

Personally, I hate changing the contra spring, and only change to a stiffer one when I see evidence of the belt slipping (it will leave black marks on the variator).

Now, if I was to install a BBK, I would go 1 range stiffer on the contra spring, and change the rollers to 1g heavier.

When changing the contra spring you have to pay close attention. I have bought a few that were supposed to fit, and sorta did, but they were either a bit too small inside, or a bit to big outside, and caused some binding. If the spring binds (or rubs) inside, or outside, it won't work properly.

A "bog" 30-40km could be caused by needle position in the carb (either too lean, or too rich).
If you have an expansion chamber, it may be the result of chamber design, as in: the pipe not working until you hit 40km. (remembering a Kawasaki triple I owned that the (Denco) pipe(s) wouldn't "hit" until 7500rpm)

[marshinman]

I had the same problem with my Marshin that has a 4t on it and what I did was to raise the pin and I used a sewing needle and cut the tip of it off and used it as a drill bit and opened up the main jet a little bit.
Took away the flat spot and gave me the acceleration.