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3rd moto, first lap, I notice I am loosing brake pressure on longer braking sections. Pull up, standing still brake pressure is fine. Do another lap and pressure is lost again, just in longer braking sections.
Bizarre to be seeing this at 14 hours, gonna try the dealership warranty, who knows if they will try the 30 days old trick.
Symptoms make me think caliper???
Any suggestions?
Sxf450
I would check for a bent caliper pin.
Caliper piston seal most likely longer braking zones length. Means the longer the piston is pushing outward. Let's air leak in the longer the hold more pressure loss.
Could be the master cylinder but more likely Caliper seals. Since they get more dirt build up. Which it probably is dirt trapped between the seal and piston.
I've come to the conclusion they don't know how to bleed the brakes at the factory. Over about 5 new Austrian bikes in the last 2 years or so, all of them got mushy front brake around 10'ish or so hours. After a flush, fill, and proper bleed with good fluid they are all great.
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Check for a bent rotor. I had one that felt fine sitting still but when you were riding it felt soft. I only figured it out because I had a 2nd wheel I put on and the brake felt nice and firm with that wheel.
I bent the caliper mount at the fork lug. Bent it back in hydraulic press but front brake still feels spungy because its not perfect. Check your fork lug caliper mount legs.
In the past when I had this, I used a flat file and a straight edge to get the mounting surfaces of the lugs re-square. You might try that to get that last little bit. Also, if the lugs were bent, it's likely the caliper bracket and/or pins are also bent. Might need to replace those.
Thank you. I will check out more items and give it ago. I can see the mount 8mm bolts were bent as well.
Damg, you guys are making me paranoid lol. Hopefully it's just a bad caliper seal and replacement kit is $20.
I did drop the bike in the pits the last ride, but I got two 20 min motos done before 3rd moto and it went out on the second corner. So seems more acute than chronic?
“Proper bleed” - what is your method that works well? I’m working on a crf master/YZ caliper that was rock solid and now it just feels a little softer than I like. If the dirt is good I can almost pull it all the way to my middle finger lol. It’s biting hard but I want it to stay firmer. Also, I do not get 100% consistent feel. Some days it does feel firmer and with more of a “brick wall” than others which is confusing. 30 total bike hours (caliper), 1 hour on the fluid, flush, and pads. All in gay shape.
Honda master, braided line, maxima Dot3+ fluid recently flushed and bled with all new banjo washers(copper), CM46 pads. 21 YZ - stock 270 rotor.
Many times a less than perfect bleed or inconsistent feel is caused by just a few micro bubbles in the upper bajo bolt or master cylinder. Try this routine -
rotate master so cap is level
remove master cap
push the caliper as far as you can with your hand so the pistons go back in. Have someone watch the fluid to see if any bubbles come out the top (don't overflow the reservoir, remove some fluid if you need to)
do full lever squeezes to pump the brake back up.
Once it builds pressure, have the fluid level set about 1/2 down the reservoir
turn the bars as far left as you can without spilling fluid. Use a t-handle or screw driver handle to tap the upper banjo as you flick the lever. Watch for any bubbles to pop out the top
turn bars full right and repeat. Do left then right a few times until you're sure no bubbles are trapped and brake is firm.
set fluid level and replace cap.
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