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That's Mrs. Hawker 2U!
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Discussion Starter · #1 ·
Ok...here's my problem. My caliper/rotor get so hot that I boil the fluid. We changed the fluid and it was cool! I had brakes for 5 whole minutes! Now I realize I brake a lot harder than these were designed for, but any ideas/advice would be appreciated.
I have a 2001 YZ80. Brake upgrades include steel lines, wave rotor and we rebuilt the MC last season. Do any of you think rebuilding the caliper would be worthwhile? There is no loss of fluid at either end of the line, except for when it boils then it goes through the banjo bolt (sp?). All I know is that it really sucks trying to ride this thing and have nothing but courage to stop it. One of these days my luck is going to run out.
Thanks in advance!!!
 

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hmm have you tired to up grade to a brake kit off a b***** bike and what kind of brake pads are you using try switching to somthing that either takes longer to heat up or that disipates heat also what kind of fluid are you using make sure it has a high enough boiling point and you dont mix fluids like puting dot 3 with dot 4 cuz if you do it makes the whole system the lower grade fluid if i think of anything else ill let you know and i hope i was of some help
 

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From back in da' day
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upgrade the brakes. Try getting a caliper / rotor kit that is a street set up like off a R6 or something. Also use a higher heat rated fluid as Jim suggested
 

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That's Mrs. Hawker 2U!
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Discussion Starter · #5 ·
ok...and how do I get the caliper/rotor onto my little yz????
 

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From back in da' day
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Go to a machine shop and have them make a mounting plate for the YZ itll cost a few bucks but itll be worth it. I know a guy who had a CBR setup on a CRF for motard. He had similar problems. I dunno why you would be having those problems though. Brakes are only needed before corners right?
 

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Forget all of the above. Trust me you cannot ride that little bike that hard.... no insult intended. The problem you have if your "boiling" the fluid is simply this.... the caliper is sticking. Try this with the bike up put on the suspect brake hard. Then let it off and see if the wheel spins freely, my bet is it wont. I can almost gauranttee you its the caliper is sticking causing the pads to drag on the rotor. The fix is either a new caliper or a rebuild.

This is a very common problem on GSXR's mine does it all the time on the rear.
 

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From back in da' day
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which is what i was thinking but didnt say. If you are boiling your fluid you are riding the hell out of the brakes! Even doing coasters and 12's on the streetbike i never boiled my fluid. I would look into a seized caliper like KH said. If you want superior braking though you can get a street set up.
 

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That's Mrs. Hawker 2U!
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Discussion Starter · #9 ·
Thank you guys....
I am not offended (KH), I know I am slamming the brakes, but not that much. I am the slowest person out there (two stroke wise) and having the most brake issues. I am not convinced a b***** brake system would work for me. I want to understand the current issue before I drop the cash on a street set up. We are getting a new line and MC. The thought here is that the banjo bolt (caliper side) became loose for some strange reason but only once. (It just wigged me out to see the fluid on my tire). We replaced the crush washers and the bolt itself-put on an R6 bolt for extra measures. The line we have on right now is way too big, goodrich only made one size to fit the 80 and the 125 so there is a lot of excess with areas to trap air. If we eliminate the "loops" in the line we eliminate the potential of trapped air. We are also thinking the MC may be scored which is how air is getting in there in the first place. We rebuilt it last year, but a rebuild doesn't fix any scoring, only the piston and seals. The caliper isn't sticking/dragging. We've checked it several times. We are thinking air is the main culprit and then that takes us back to the MC. Reason being that there never is any leakage from the caliper side other than that one occasion the banjo bolt got loose. When I originally posted, I was confused about the caliper but now I understand!!! *see light bulb here!* :lao After we get the air out of the line, we'll be better able to assess whether or not the caliper is sticking.
Thanks for all the advice guys, it's appreciated!
 

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Combat Marshmellow
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i say get a street set up with a brembo master and then get back to kicking ass....
 

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Air could be a possibility also. The air will expand when it gets hot and make the brake drag. You may need to pull the caliper and hold it high up and tap it to get it bled completely. Dragging the brake will also do it like Reck mentioned.

The scoring comes from not changing the fluid enough. If you flush the system out every few months it will prevent this from happening. The reason is that brake fluid by design absorbs moisture (thats why they always say use a NEW can and not the old one from the trunk of your car) after a while the fluid will have water in it and the water will make its way to the aluminium of the caliper and cause pitting and in bad cases scoring and sticking pistons.

Brake fluid is cheap all you need is a good brand DOT 3 and flush the system out with fresh stuff every so often. Alot cheaper than master cylinders and calipers :) Its a couple minute job if your careful not to let air in when flushing it.
 

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Resident Freak
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If after trying all of the above you still have no luck, PM me and I'll look up the ad I saw in the back pages of the latest Cycle News. The ad was for a brake caliper with hella-deep cooling fins cut into it specifically to reduce overheating. The ad claimed a 30% reduction in brake fluid temperature. I'm sure it could be adapted to fit. Good luck -
 

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That's Mrs. Hawker 2U!
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Discussion Starter · #14 ·
Thanks Drifter!
We just got all the parts in today so tomorrow and Saturday are wrenching days....I'll be able to report back on Sunday because we have a race Saturday night.
Hopefully it will all work out!!!
 

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Resident Freak
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Krazy Hawaiian said:
Cycle News..... dang I aint seen one of them in years!!
Yep - a fellow I work with by the name of Ted Presson is big into dirtbikes. He used to race professionally and was the man responsible for the KTM 400 in my garage. I'm now learning to ride dirt...

At any rate, he gives me his copy each week when he's done with it. I'm amazed that I never found it on my own. It's absolutely packed with great coverage of all types of racing, and often covers new models.

Good periodical -
 
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