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Old 11-30-2014, 04:42 PM   #1
BungiFungi OP
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Joined: Oct 2012
Location: North Carolina
Oddometer: 2
1986 Kawasaki KLR 250 Brake adjustment/bleeding questions

So, as most of my questions start, I screwed something up trying to fix things.

I had taken the wheel off the front, and replaced the tire. That went well.

However, I could not get the rotor back into the caliper as it was too tight. So, I compressed the caliper piston so that the pads would not block me from putting the wheel on. Now that I got the wheel on the bike, the brake does nothing. You can grab the whole handle all the way down and no friction is created, however it is rubbing a slight amount on the fixed side. Oh, and I compressed the brake while the wheel was off because I am an idiot.

Does this mean that I got air in my line and need to bleed it? Or is this simply an alignment issue? How can I push that piston back out? I have tried pumping the lever but it does not come back out.

Oh, and I can see there is fluid in the master cylinder, but the two philips screws on top were stripped by the P/O. I bought replacement screws, but don't know how to get the existing ones out. Any ideas on this situation? Thanks everyone
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Old 11-30-2014, 08:14 PM   #2
Bigger Al
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Joined: Oct 2004
Location: Auburn, CA
Oddometer: 7,856
I'll start with the stripped screws.

Get a drill that's just slightly larger than the outer diameter of the screws, and very gently drill the heads off. Take your time. Once both heads are off you can remove the cover. There should be enough of the screw shanks left to grab with small vice grips.

Now is a good time to renew the brake fluid while you're in there. Open the bleeder nipple on the caliper and let all of the old stuff flow out. At this point you can add fresh fluid and allow it to fill the line and run out at the nipple, or you can close the nipple at various points during the refill to keep the mess down. Bleed the system.
My favorite tool for adding fluid to a completely drained system is an irrigation syringe with a 8"-10" piece of tubing attached. This allows the fluid to be pushed up from the bottom, through the nipple, and into the system. It's a time saver, but be certain that the end of the tubing is securely on the nipple. More than once I've managed to lay a very nice line of DOT4 across the garage ceiling.

If you cannot get the piston to push out, then more in-depth work might be necessary. Drain the system again. Undo the line at the caliper and remove the banjo bolt. Put a rag under the caliper to keep the spill down, and to catch the crush washer that might fall loose. It goes between the fitting and the caliper. Now for the potentially tricky part: I will sometimes get a blow gun with a rubber-tipped nozzle, drop the regulator down to 5 PSI or so, and shoot some air into the hole where the fitting was. This will gently force the piston out towards the brake rotor. Do not exceed the 5 PSI if you can help it. Things can get messy pretty quickly if you do.
Reattach the fitting, paying attention to the crush washers (use new ones if you have them) and try the fill/bleed process again.

Let us know how it goes.
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Old 12-03-2014, 05:50 AM   #3
Yamarocket630
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Location: M-boro, TN
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Depending on how far you pushed the pistons back, you have have to pump that brake lever 10-30 times to return the pads all the way back out to full contact with the rotors.
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Old 12-04-2014, 12:26 PM   #4
markk53
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Joined: Dec 2007
Location: Delaware Ohio
Oddometer: 8,152
Vacuum bleeder from Harbor Freight under $30 and the best $30 you ever spend - eliminates the headache of pumping. Just use minimal vacuum and close the bleeder before you empty the reservoir or have someone pouring fluid in the reservoir. Light vacuum to draw fluid through avoids sucking air past the seals that are meant to seal against inside pressure, not vacuum.

While you are at this stage you may want to pop the pistons out of the caliper and clean them and the bores up with a very fine 1000-1500 grit wet/dry or scotch pad if needed. Odds are the seals are fine and reusable if you wish.

When you go to replace the screws on the master cylinder reservoir get some countersunk allen heads, zinc coated at a good hardware store, like some Ace Hardware. Odds are Lowes or Home Depot may not have them. Any problems, give a yell, I have some I got from Fastenal, but they usually require you buy in quantity - never hurts to ask though. Used them in my own bikes. They're an M5-.8 I think, but verify it. The hex is 4mm if I remember right. The black oxide rusts too fast and the allen head makes it easy to snug up or remove compared to the JASO phillips heads.
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