Severe pulsing in front brake lever

Well the evening long thunderstorms interfered with any discovery on my rotors last night. Then the girlfriend moved in for the kill and came over thinking why would I be getting the bike ready to ride if I can’t even go riding. That was the nail in the coffin, and we went out to the local pub.

SO the rotors are not yet on the front wheel, but with any luck they will be tonight. Though my neighbor has my help promised for hanging six 4x8’ sheets of 17/32” subflooring…overhead in his garage tonight. It will be a miracle if I get the wheel and brakes back on and a test ride in tonight. But rest assured I will report back any and all finding.

I’ll be back when the the rotors have revolved under power of an inline-4…

sheik*yerbouti wrote:

. . . rest assured I will report back any and all finding.

I’ll be back when the the rotors have revolved under power of an inline-4…

10 days later. . .?

I had set notify on this thread and - thanks for jogging my memory KaZoo!

The short answer is that they are now 100% unequivocally fixed. The wicked 1/2” pulse at the master cylinder has been relegated to my memory of odd motorcycle behaviors of the past.

Aside from the machinist saying that the rotors were .004 to .009 out of true (this is after his employee’s did an initial cut) with the surface that mates with the hub, he told me to scrutinize the mating surface on the hub as well. While the powder coater had masked off the mating surface, a small uneven ridge or lip was present on the outer circumference of the hub where the rotor would mate.

I removed this with a fresh couple of razor blades from both sides of the hub and also scotchbrited + WD40 the mating area of the hub and reassembled torquing in a figure “4” pattern to 5, 10, 15, 20, and finally 30 ft-lbs.

The lever now feels like any other carefully prepared motorcycle brakes I have ever felt - rock solid. Thoughts of feeling of any type of stutter, pulse or uneven braking action do not even enter into my mind.

I did such little braking with the front calipers during the pulsing that I feel the pads survived and I’ve re-bed them into the re-cut rotors and everything is great.

Some pics…

One of the universe's great unsolved mysteries, solved at last. . .

HoRaY for you!

What did the rotor turning cost at the machine shop, btw? As in per rotor?

Enquiring minds want to know.



:lol:

Well this machine shop is next to a IT shop I managed for about 5 years. I can't say I'm buddies with the owner but he was willing to do a favor.

The employee's charged me $45 for the pair. It took them slightly over 3 hours I remember him saying. That would normally be $180. Even at that price, had they been done correctly, would have been acceptable because have you not only found, but priced a NOS rotor? $200 and beyond each. I saw a pair of NOS front Kawi rotors still in the packaging for $650 at the MidO Vintage Swap meet.

The rework was free.

KaZooCruiser wrote:

One of the universe's great unsolved mysteries, solved at last. . .

HoRaY for you!:lol:

Are you making fun of me ponk!

Still I find it hard to believe (though I do) that *nine thousands of a freaking inch* at the rotor, under a 41mm piston can translate to *five tenths of an inch* up on the 16mm master cylinder.

it must be the ratio of the two large 41mm (1.6") caliper pistons, which when each is displaced back .009" is gonna move (1.6" x 3.14) = 5.02 x 2 (2 pistons) = (10.04 x rotorwarp (.009") = .45 (fluid units unknown) of fluid back up to the master and that is going to displace a single 16mm (0.62") master cylinder piston a bunch! master cylinder piston (0.62" x 3.14) = .45 (fulid volume moved) divided by "X" = 1.94 (surface area of master piston) and x would = .23" - there is the 1/4" of movement at the lever!!

i've had 3 beers and it makes sense to me!!!!!!!!!!!!!



Post edited by: sheik*yerbouti, at: 2007/08/20 17:55

after a number of alcho-pops. . .

three sheiks to the wind *yerbouti wrote:

Are you making fun of me ponk!

na. . .I was holding my breath in suspense over the drama. . .now I can breath again.

:woohoo:

sheik*yerbouti wrote:

. . .
While the powder coater had masked off the mating surface, a small uneven ridge or lip was present on the outer circumference of the hub where the rotor would mate.

I removed this with a fresh couple of razor blades from both sides of the hub and also scotchbrited + WD40 the mating area of the hub and reassembled torquing in a figure “4” pattern to 5, 10, 15, 20, and finally 30 ft-lbs.

Glad your machinist redid your rotors for free. . .there is the outside possibility that the ridge you found and cut off the hub was enough to warp them the first time they were installed.

And you are right about replacement prices. Obscene.