TT250 odd front brake issue

'16 TT250 · 08-18-2016, 09:07 PM

When the bike sits for several days or weeks the front brake doesn't work 'till I pump it a few times. Never experienced this on another bike, and I've had plenty. I've had a few that would do this with the rear brake, some that even had to be bled; I assume because the reservoir is close to the same level as the caliper. SV 650's seem to be high on the list for the rear brake doing this.

The TT's reservoir looks to be completely full, no bubble in the sight glass, which would leave little air space so maybe temperature changes are creating a vacuum or something.

Not trying to solve it, just thought I'd mention it in case someone else has the same issue they won't feel alone. If I decide to address it and find the cause I'll post it for others.

pistolclass · 08-18-2016, 09:51 PM

I think it is the piston and the transmission. The Bike is toast..... I'll take it off your hands for $100.

Honestly sounds like air in the system. check for tiny leaks and bleed.

My $100 offer still stands

Ariel Red Hunter · 08-18-2016, 10:25 PM

Quote:

Originally Posted by pistolclass

I think it is the piston and the transmission. The Bike is toast..... I'll take it off your hands for $100.

Honestly sounds like air in the system. check for tiny leaks and bleed.

My $100 offer still stands

What a guy! A generous offer to get that dog off your hands (and off of your mind) Such a deal, let him deal with the issues. It is re-assuring to know that the milk of human kindness is still around!

Predacon · 08-18-2016, 10:40 PM

Quote:

Originally Posted by '16 TT250

When the bike sits for several days or weeks the front brake doesn't work 'till I pump it a few times. Never experienced this on another bike, and I've had plenty. I've had a few that would do this with the rear brake, some that even had to be bled; I assume because the reservoir is close to the same level as the caliper. SV 650's seem to be high on the list for the rear brake doing this.

The TT's reservoir looks to be completely full, no bubble in the sight glass, which would leave little air space so maybe temperature changes are creating a vacuum or something.

Not trying to solve it, just thought I'd mention it in case someone else has the same issue they won't feel alone. If I decide to address it and find the cause I'll post it for others.

I had the same exact issue with mine. The front brake had been working pretty well but when I returned from a week long trip I had completely lost front brake. I pumped several times and was able to get it back but it sure had me worried. I decided to flush the front brake with fresh dot 4 and have not had an issue since. I noticed the original fluid in the reservoir had a milky white color and funny smell as if it was the incorrect fluid from the factory. Anyway, I would recommend you flush it out whether it is the odd fluid causing the issue or air trapped up at the reservoir. Also, the big bonus was now the front brake is very firm always and in general works much better than recieved. That front brake is a little bit of a pain to bleed but I think you will find it is worth the effort.

pistolclass · 08-18-2016, 11:41 PM

Prior to my hawk purchase I haven't ridden in 20+ years. My hawk brakes seem decent with the rat piss they put into the reservoir. I think I'm just used to braking from bikes from the 80s. I think this weekend's project is to bleed my brakes to see the improvement. Just any dot 4? Any recommendations?

2LZ · 08-19-2016, 10:12 AM

The reservoirs are overfilled and the fluid is junk.
Bleed it with some good DOT 4 and make sure and leave a little bubble in the glass.

Weldangrind · 08-19-2016, 11:42 AM

Agreed. Work at displacing all of the original fluid with new stuff. I use DOT 3, but only because I have quite a bit of it. It's very important to ensure that you don't overfill the master, or the brakes can lock up on you.

Ariel Red Hunter · 08-19-2016, 03:42 PM

Quote:

Originally Posted by 2LZ

The reservoirs are overfilled and the fluid is junk.
Bleed it with some good DOT 4 and make sure and leave a little bubble in the glass.

Any DOT 4 is superb stuff. I think most of the problems with C/B fluids is from sitting so long before they get here. Condensation.

mtiberio · 08-21-2016, 05:37 PM

sure enough, I came back from 6 weeks out of town, and the front brake lever comes back to the bar, and no amount of pumping will make it firm. Looks like I need to bleed. Of course I had to drill out one of the res screws. Luckily I had something on the shelf that will work til CSC come thru.

mtiberio · 08-21-2016, 07:21 PM

Changed fluid to dot 4. Now have brakes

Ariel Red Hunter · 08-21-2016, 07:39 PM

Quote:

Originally Posted by mtiberio

Changed fkuid to dot 4. Now have brakes

Great. Good deal - and now you know.

'16 TT250 · 08-22-2016, 06:52 PM

I decided to take a peek in the reservoir. The screws were really hard to break loose, enough that it distorted them a little. As soon as I cracked the second one loose some fluid squirted out. Being that I wasn't planning to bleed I just put it back on. The brake came back to what seemed normal the first few times it sat, now it won't. There's some brake, but the handle is quite mushy. I don't have any plans on riding it and may not be keeping it so I'll leave it be for now.

Edit: there's really no need for DOT 4 unless you plan to go road course racing, DOT 4 just has a higher boiling temp than 3. Sport bikes started going to DOT 4 then most other bikes followed suit. Some say that 4 is less hygroscopic but I don't see any advantage to that.

oddthought · 08-23-2016, 10:42 AM

I'm actually glad that I fell off my bike and broke the brake lever mount on the reservoir. Since I had to replace it, I figured I'd drain the fluid and replace it with DOT4 (which I had handy from other projects). The braking was radically changed with just that one adjustment. I had never ridden a bike with as bad a front brake, and now it's one of the better one's I've ridden. I also got to avoid dealing with the nasty screws on the old reservoir, which were stuck solid.

As far as DOT3 vs DOT4, the one thing I like about DOT4 better is that it is less hygroscopic. This means it has less of a tendency to pull moisture out of the air, which ruins the fluid. In turn, that means you can use the whole bottle of fluid without worrying about its contamination from having been opened.

'16 TT250 · 08-23-2016, 11:03 AM

Maybe someone with an actual education on this stuff can provide more info.

My understanding is that a hygroscopic fluid is one that can attract and hold water molecules in suspension. Water molecules (humidity) enter the system by coming in through the rubber (permeability) or by breathing if it's not a sealed system. The brake fluid can't make water, it has to get in somehow. Therefore I theorize that neither fluid can increase the amount of water in the system, only how much water that fluid can hold in suspension. It would seem that a more hygroscopic fluid might actually be better. A non-hygroscopic fluid such as silicone won't hold water in suspension therefore any that gets in will remain as water in direct contact with the brake parts which could lead to corrosion. Since the water will sink just like water in oil it will accumulate at the lowest point in the system and will be hard or impossible to remove by just bleeding/flushing.

Just my theories, I'm not claiming any of this to be fact and haven't researched any of it yet.

2LZ · 08-23-2016, 11:10 AM

Quote:

Originally Posted by oddthought

Since I had to replace it, I figured I'd drain the fluid and replace it with DOT4 (which I had handy from other projects).

As far as DOT3 vs DOT4, the one thing I like about DOT4 better is that it is less hygroscopic. This means it has less of a tendency to pull moisture out of the air, which ruins the fluid. In turn, that means you can use the whole bottle of fluid without worrying about its contamination from having been opened.

...and it's all I buy now and have on the shelf. Its usually within a buck or so of the DOT 3. Worth the extra shilling.

08-18-2016, 09:07 PM	#1
'16 TT250 Join Date: May 2016 Location: Hacienda Heights, Ca Posts: 281	TT250 odd front brake issue When the bike sits for several days or weeks the front brake doesn't work 'till I pump it a few times. Never experienced this on another bike, and I've had plenty. I've had a few that would do this with the rear brake, some that even had to be bled; I assume because the reservoir is close to the same level as the caliper. SV 650's seem to be high on the list for the rear brake doing this. The TT's reservoir looks to be completely full, no bubble in the sight glass, which would leave little air space so maybe temperature changes are creating a vacuum or something. Not trying to solve it, just thought I'd mention it in case someone else has the same issue they won't feel alone. If I decide to address it and find the cause I'll post it for others.
	0

08-19-2016, 10:12 AM	#6
2LZ Join Date: Mar 2010 Location: Volcano, Ca Posts: 7,080	The reservoirs are overfilled and the fluid is junk. Bleed it with some good DOT 4 and make sure and leave a little bubble in the glass. __________________ "Light a fire for a man, and you heat him for a day. Light a man on fire, and you heat him for the rest of his life." 2007 Suzuki DRZ400S (SM convert) 2009 Q Link XP 200 1967 BSA B25 250cc Starfire 2022 Royal Enfield Interceptor 650 2023 Royal Enfield Scram 411 1948 Royal Enfield Model G 350
	1

08-19-2016, 11:42 AM	#7
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Agreed. Work at displacing all of the original fluid with new stuff. I use DOT 3, but only because I have quite a bit of it. It's very important to ensure that you don't overfill the master, or the brakes can lock up on you. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

08-21-2016, 07:21 PM	#10
mtiberio Join Date: Jun 2016 Location: Arlington, VA Posts: 258	Changed fluid to dot 4. Now have brakes Last edited by mtiberio; 08-22-2016 at 01:16 AM.
	2

08-23-2016, 10:42 AM	#13
oddthought Join Date: Apr 2016 Posts: 164	I'm actually glad that I fell off my bike and broke the brake lever mount on the reservoir. Since I had to replace it, I figured I'd drain the fluid and replace it with DOT4 (which I had handy from other projects). The braking was radically changed with just that one adjustment. I had never ridden a bike with as bad a front brake, and now it's one of the better one's I've ridden. I also got to avoid dealing with the nasty screws on the old reservoir, which were stuck solid. As far as DOT3 vs DOT4, the one thing I like about DOT4 better is that it is less hygroscopic. This means it has less of a tendency to pull moisture out of the air, which ruins the fluid. In turn, that means you can use the whole bottle of fluid without worrying about its contamination from having been opened. __________________ Previous: '80 KZ550, '04 Shadow 750, '12 NC700X Current: CSC TT250
	1

08-18-2016, 09:51 PM	#2
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 978	I think it is the piston and the transmission. The Bike is toast..... I'll take it off your hands for $100. Honestly sounds like air in the system. check for tiny leaks and bleed. My $100 offer still stands
	2

08-18-2016, 11:41 PM	#5
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 978	Prior to my hawk purchase I haven't ridden in 20+ years. My hawk brakes seem decent with the rat piss they put into the reservoir. I think I'm just used to braking from bikes from the 80s. I think this weekend's project is to bleed my brakes to see the improvement. Just any dot 4? Any recommendations?
	0

08-21-2016, 05:37 PM	#9
mtiberio Join Date: Jun 2016 Location: Arlington, VA Posts: 258	sure enough, I came back from 6 weeks out of town, and the front brake lever comes back to the bar, and no amount of pumping will make it firm. Looks like I need to bleed. Of course I had to drill out one of the res screws. Luckily I had something on the shelf that will work til CSC come thru.
	0

08-22-2016, 06:52 PM	#12
'16 TT250 Join Date: May 2016 Location: Hacienda Heights, Ca Posts: 281	I decided to take a peek in the reservoir. The screws were really hard to break loose, enough that it distorted them a little. As soon as I cracked the second one loose some fluid squirted out. Being that I wasn't planning to bleed I just put it back on. The brake came back to what seemed normal the first few times it sat, now it won't. There's some brake, but the handle is quite mushy. I don't have any plans on riding it and may not be keeping it so I'll leave it be for now. Edit: there's really no need for DOT 4 unless you plan to go road course racing, DOT 4 just has a higher boiling temp than 3. Sport bikes started going to DOT 4 then most other bikes followed suit. Some say that 4 is less hygroscopic but I don't see any advantage to that.
	0

08-23-2016, 11:03 AM	#14
'16 TT250 Join Date: May 2016 Location: Hacienda Heights, Ca Posts: 281	Maybe someone with an actual education on this stuff can provide more info. My understanding is that a hygroscopic fluid is one that can attract and hold water molecules in suspension. Water molecules (humidity) enter the system by coming in through the rubber (permeability) or by breathing if it's not a sealed system. The brake fluid can't make water, it has to get in somehow. Therefore I theorize that neither fluid can increase the amount of water in the system, only how much water that fluid can hold in suspension. It would seem that a more hygroscopic fluid might actually be better. A non-hygroscopic fluid such as silicone won't hold water in suspension therefore any that gets in will remain as water in direct contact with the brake parts which could lead to corrosion. Since the water will sink just like water in oil it will accumulate at the lowest point in the system and will be hard or impossible to remove by just bleeding/flushing. Just my theories, I'm not claiming any of this to be fact and haven't researched any of it yet.
	0