Jumpiness in the brake lever action

[Lukich]

Hi.

Recently I started noticing the following behavior in my front brake lever - as I start squeezing it progressively to load the front tire, about the first half of the lever travel is nice and smooth. However, on the second half, it sticks for a bit in certain positions and then jumps, which results in jumpy brake application. I tried it on the stationary cold bike and see the same thing - first half smooth, second half sticking and jumping.
Any ideas of what this can be?

Thanks!
Luka

 

[stangmx13]

potentially any of these, in order of most to least likely:
- dirty rotors
- bent/warped rotors
- bad brake pads
- dirty calipers

first, id try cleaning the rotors w/ brake clean, scuffing them with emery cloth, and cleaning them again with alcohol. scuff the brake pads as well. then break-in the pads again with some progressive braking without actually stopping hard.

 

[byke]

I assume it's on the SV? I don't know the way in which the lever presses on the plunger on the SV, but on my bike it's a rounded metal piece when presses on a flat metal piece and the rounded piece doesn't always press exactly in the center, it starts at about 1/3 in from the edge and then *slides* on on the flat piece as you squeeze. When it's dry, it does that jumpy business. Try a small dab of grease where they meet and see if that changes anything.

 

[Lukich]

Thanks for prompt reply. However, it suggests that the problem stems from contact of pads with rotors, but I tried the same thing on a stationary turned off bike, so there was no rotation involved.

 

[Lukich]

Thanks, I will try it. Any particular type of grease?

I assume it's on the SV? I don't know the way in which the lever presses on the plunger on the SV, but on my bike it's a rounded metal piece when presses on a flat metal piece and the rounded piece doesn't always press exactly in the center, it starts at about 1/3 in from the edge and then *slides* on on the flat piece as you squeeze. When it's dry, it does that jumpy business. Try a small dab of grease where they meet and see if that changes anything.

 

[mototireguy]

When was the brake fluid last changed/flushed?

Spritz a little WD40 in around brake lever pivot and where it makes contact with the master cylinder piston.

 

[Lukich]

I bought the bike from the dealer about three month ago, so I'm pretty sure it was changed then. I'll try it, thank you.

When was the brake fluid last changed/flushed?

Spritz a little WD40 in around brake lever pivot and where it makes contact with the master cylinder piston.

 

[dravnx]

I bought the bike from the dealer about three month ago, so I'm pretty sure it was changed then. I'll try it, thank you.

That's so cute. :rofl

 

[Lukich]

That's so cute. :rofl

Well, it's a used bike, and the dealership is a two-person operation specializing in reselling of used bikes called MotoJava, so yes, I'm pretty sure they changed the fluids.

 

[Phanuel]

You assume much young padawan.

What color is the fluid?

 

[dravnx]

Well, it's a used bike, and the dealership is a two-person operation specializing in reselling of used bikes called MotoJava, so yes, I'm pretty sure they changed the fluids.

Unless they have a show room full of brand new motorcycles and atv's and big signs saying Honda/Kawi/Yamaha........they are not a dealership. They are a couple of wrenches fixing and reselling motorcycles. They make their living buying low and selling high. This doesn't mean they are not good wrenches or good businessmen but keep it in perspective. It's your motorcycle and your safety. Don't assume anything.

 

[Lukich]

So, after closer investigation of the lever, it turned out that the but that holds it in place unscrewed itself, which seems to have made the lever looser and resulted in that jumpiness. Screwing it back on fixed the issue, I guess I need to put some threadlocker on it for good measure.

Thanks for your help!