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MOT Failed

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I'm not giving you any abuse :I only trying to help you fix it!
We don't import that model but you can bet we have those same brake components on similar models., there is nothing model specific in that bikes brake design, the quality of the product will be very comparable to a similar bike here and it doesn't even have the added complexity of ABS to troubleshoot.
 
Brian P said:
You are writing this on an internet forum that is based in Canada.

We don't have MOT tests here. We have something like it, but it's not called that.

We don't have that bike model here in Canada. Therefore, for those TWO reasons, no one that you are talking to will have had that specific issue on that specific bike.

That adds up to, "you're talking to the wrong people".

Nevertheless, brakes are brakes, and the technical answers that you were supplied with are as helpful as can be expected under the circumstances.


You've either got air in the brake line, or seals somewhere in the brake system that are knackered (and there are only two places that have seals, the master cylinder, and the caliper), or the pistons inside the calipers themselves are munged up with dirt and brake pad dust so that the pistons are not going out and in properly.

That's it. Find the problem and fix it. There's an ocean between where we are, and where you are.
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If you have read my posts you will see new seals have been fitted brake fluid replaced with no air in system all pipes are good. Even though this site is based in Canada there are still people from the uk on hear and they may have had this issue. As for saying im a twat there is no need for profanity of any sort on a public forum so im my opinion if you haven't had the issue im asking about with the motorcycle in question DON'T offer an opinion as i wouldn't offer on a subject i haven't encountered before.

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Is something bent?

Brake rotor warped? Front end of the bike is misaligned so that the brake caliper is not squarely gripping the rotor?

Bent parts and/or misalignment will cause the pistons to be pushed back further than they should, which results in subsequent brake application requiring more fluid, which means the lever will come in more.

Loosen the two bolts that secure the caliper to the fork leg a couple of turns and then squeeze and release the brake lever a couple of times. If the brake lever operates as it should in this condition, then something is bent or misaligned.

When replacing brake caliper seals, it can be tricky to get all the air out of the caliper.
 
Brian P said:
Is something bent?

Brake rotor warped? Front end of the bike is misaligned so that the brake caliper is not squarely gripping the rotor?

Bent parts and/or misalignment will cause the pistons to be pushed back further than they should, which results in subsequent brake application requiring more fluid, which means the lever will come in more.

Loosen the two bolts that secure the caliper to the fork leg a couple of turns and then squeeze and release the brake lever a couple of times. If the brake lever operates as it should in this condition, then something is bent or misaligned.

When replacing brake caliper seals, it can be tricky to get all the air out of the caliper.
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No misalignment had the caliper off and blocked the piston and still continues to the handle bar even if you pump the brake first. This has happened since the bike was new 3 years ago Yamaha say this is normal but MOT tester has failed it for insufficient reserve travel. So was wondering if anyone else has had this issue


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This really does sound to me like the master cylinder needs rebuilding, would be the same with any bike
 
OP is not interested in fixing anything.

No one here has a YB.

No one here has gone through the MOT inspection.

The OP will not find the info he’s looking for from us.
 
get some vice grips and bend the brake lever outwards until it no longer touches the bar....

09_brake_lever.jpg
 
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lowekevinjohn said:
No misalignment had the caliper off and blocked the piston and still continues to the handle bar even if you pump the brake first. This has happened since the bike was new 3 years ago Yamaha say this is normal but MOT tester has failed it for insufficient reserve travel. So was wondering if anyone else has had this issue


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I vaguely remember someone complaining about this with a bike many years ago in a magazine however, I don't know what manufacturer or resolution was. I wouldn't be surprised if it was Yamaha though. I think the answer is to get a letter direct from Yamaha stating that this is how the bike functions and there is no defect. An aftermarket fix might be to use a master cylinder or brake lever from a different bike that changes the throw, not sure which one would do the job though. I would go the letter route first.
 
caboose56 said:
OP is not interested in fixing anything.



No one here has gone through the MOT inspection.
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I have, but that’s was when I lived in England ;).

OP, you asking a question about MOT inspection in this forum is similar to a Canadian posting a question on londonbikers.com about maple syrup or poutine lol.

Let’s me guess you’re from Somerset ? :)
 
lowekevinjohn said:
If you pull hard enough it reaches the handle bars but the brake efficiency is good and i know air compress no disrespect im a mechanic by trade and a former MOT tester my issue is that even after the brake locks out he continued to pull the lever until it touched the handle bars

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The MOT brake test guidelines are depressingly subjective; "hard enough" could mean anything as it could be Twiggy

220px-Twiggy_promo.jpg


or this guy doing a pull test:

massive-forearms.jpg


Would be nice if they specified a force in, say, Newtons, to be applied for the test. You might seek the opinion of a different inspection station; maybe they'll have Twiggy on shift... :)

Let's stipulate that the bar shouldn't touch in "normal" use. A few things that can lead to this include:

- excessive play in the pivot; how much lost motion is there at the lever pivot
- excessive gap between the lever and the master cylinder piston; how much lever movement takes place before the piston in the M/C starts to move?
- a deformed (previously bent, not bent back properly or replaced) lever; has the lever ever been bent and if so, was it "bent back" or replaced?
- something other than hydraulic fluid is in the circuit (e.g. air), something which has a degree of compressibility
- "give" in the system when under pressure (e.g. a line aneurysm or bulge, spreading caliper body.)
- an external leak; pressure is being lost due to fluid leaking out of the circuit (e.g. past the piston seals in the caliper)
- an internal leak; pressure is being lost within the hydraulic circuit past internal seals of the master cylinder

Or or more of the above is happening in your case, mate.

These (and whatever other potential causes) aren't unique to UK-market bikes. Any hydraulic braking system can have the exact same issues.
 
Yes, I've had this exact issue with my YBR 125.

Check the following.


--Has the brake been bled? (common cause of this is air in the line)

--Are your pads the required thickness? If not, replace them.

--Is one of your brake lines damaged causing expansion? Change the line if it is.

--Is the brake caliper boot leaking? Get a mech to replace it.

The front brake is very simple. It should not be hard to repair.
 
lowekevinjohn said:
No misalignment had the caliper off and blocked the piston and still continues to the handle bar even if you pump the brake first. This has happened since the bike was new 3 years ago Yamaha say this is normal but MOT tester has failed it for insufficient reserve travel. So was wondering if anyone else has had this issue


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Click to expand...

We don’t have this bike in Canada. Therefore, no one else has, or ever will have this issue with this or any other bike put through an MOT inspection. We don’t have MOT inspections here.

Does the Yamaha dealer who said “this is normal” do MOT inspections? If so, take it there. If not, go there anyways face-to-face and ask how they are going to solve your problem.


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Your brake hose is blowing up like a thick balloon and if it didn't then something else would blow, like the brake master cylinder seal.

... oh, and yes I have dealt with that exact part failure on a couple of different bikes. Is the exact reason people spend the big money to upgrade their brake lines to stainless steel weave!
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