Sunday, January 20


Unlike a lot of Hyosung owners, i've never had any problems with my yellow beastie. It could be that i haven't put many kays on her, as despite my best efforts, my only riding appears to be done for commuting purposes. And since i live something like 4 ot 5 kms from where i work, it's not a whole lot of commuting that i do.

However I had the first mechanical issue with it last week.

My front brakes started to seize badly out of nowhere. I'd ride the beastie to work in the mornings and she would be fine, no issues. Then 8 or 9 hours after being parked at work, brakes would start seizing, to a point where:

  1. I'd not be able to back her up at all
  2. One day, i rode most of the way home without touching the brakes - the calipers were clamped tight on the discs all the way. This scared the bejesus out of me, as it meant:
    • She'd buck and nosedive when clutching in to change gear
    • I'd be dragging ass moving from a standing start (surprised drivers tailing me really closely)
    • Cornering was just... scary.
I had a look on the Google to make sure it wasn't something i was doing and came across this:
Brakes...master cylinder
The master cylinder is where the brake fluid is kept...usually attached to the handlebar for front brakes and tucked away, close to the rear brake pedal for the rear brake. The main problem that occurs with these is the brake fluid itself. There is a piston in the master that is activated by the lever that you pull. If this piston is leaking then the brakes can be mushy or there may be brake fuid leaking from the area around the master cylinder. There is a very small hole in the master that allows brake fluid to return back up to the master and if this is blocked due to corrosion then the lever will be very hard but no or little braking action will be taking place. If you experience problems with a master cylinder then you may be better off paying someone to look at this for you.

Brake Calipers
In the caliper a piston is activated by you when you pull the front brake lever. It pushes against the actual brake pads to apply pressure on the disc. One or several (depending on make) "rubber" o-rings seal the fluid from escaping between the piston and wall of the caliper. These rings serve another function and that is to return the piston to its original position (brakes off) These rings are the only thing returning this piston and when there is corrosion, the piston can be forced on because the hydraulic pressure is great enough to do so, however there is no (hydraulic) help for the piston to return and thus causes the brakes to be applied even though we are not pulling the lever. The resulting application of the brakes causes a heat build up, brake fluid expands (due to heat) thus forcing the brakes on even more. This is not a good situation to be in as a motorcyclist

I've seen bikes pull into the shop with the rear disc brake so hot that it is glowing cherry red with heat build up. The brake pads were totally worn away and the repair parts this bike would need include caliper assembly, disc brake rotor, wheel bearings and all dust seals. Expensive!!!

Article link

I don't know my bike mechanically, but it certainly sounded as though that could have been the problem, especially since it was playing up most on hot days (which we've had a few of). Took her to the shop and it did turn out to be a piston/valve/switch in the cylinder that wasn't adjusted properly, and thus wasn't letting the air out - at least, that's what i could gather from the mechanic, who sounded like he would probably have been more comfortable speaking German or French than trying to explain a mechanical issue in layman's English... which i made him do, poor guy.

But it's all fixed up now, and under warranty so i didn't have to fork out a cent. Bike is back to itself!

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