1. It bleeds the fluid through the module but not through the solenoid controlled valves and chambers. These only actuate when the system cycles. (which is why there is a tool that cycles the system for fluid changes) You are replacing the bulk of the fluid but the fluid in those areas doesn't get changed. It will get flushed with new fluid as system cycles and it is a very small percentage of the total fluid in the system. But as in any fluid change you are never getting every bit of old fluid out.

2. If you turned on the ignition while bleeding and there were air bubbles in the line that you had not bled out yet, they could get cycled into the abs and then you would have to have the system bled with the proper equipment to cycle the fluid through. Your reservoir can be full and you can still have air in the line that could get "pushed" into the solenoid actuated chambers of the system. the next time your abs activated you would have a loss in braking effectiveness.....probably not a desirable time for that based on the fact the your abs is kicking in.

 

I had the same question so I looked it up in the service manual, bought the recommended bleeder and changed the fluid. simple enough.

 

Thanks for the explanation. I figured it went something like that. Good to know it will eventually get cycled through the module.
My thought was what good is it to flush the system if the old fluid never worked its way through the abs module.

 

Go to the dollar store and buy a cheap turkey baster. Remove master cylinder cover and remove all old fluid you can. Wipe the inside of the master cylinder reservoir clean, then refill with new fluid. This step insures you will be getting clean fluid thru the system sooner.
Then, I use my Mity Vac to pull the fluid out the bleeders as I keep topping off the master cylinder reservoir. Keep fluid in the reservoir, no air in the lines, power off, never a problem with the ABS.
And, always be sure to use the correct fluid for your scoot.
Ride safe!