automatic fork bleeders/pressure changer thing?


7 replies to this topic
  • Bigdong

Posted August 09, 2010 - 11:50 AM

#1

Hi,

i have a yz450f and on the fork i have connected 2 tubes that go into canisters. Im guessing that it is somne kind of automatic bleeding device but not sure exactly.

Can anyone fill me in on what these are and if they have any advantage over conventional fork bleeders.

thx

  • CaptainKnobby

Posted August 09, 2010 - 12:18 PM

#2

Are you talking about the push button type bleeders? or A tube (like a gas line)?

  • Mr. Neutron

Posted August 09, 2010 - 12:57 PM

#3

Possibly subtanks? Is there a "valve handle" you can turn to restrict or increase flow from the forks to the reservoirs? What year is your YZ? I was under the impression that subtanks were for open chamber forks, but could be wrong about that..... Heck my whole response is a big guess, so I could be wrong about everything here..... :banana:


Jimmie

Edited by Diesel Goober, August 09, 2010 - 04:01 PM.
correct a spelling error.....


  • grayracer513

Posted August 09, 2010 - 02:22 PM

#4

They are called "sub tanks". Their purpose is to increase the air volume in the fork so as to allow you to run more oil in it without the harsh feel you would usually get from doing so. If you have an '04 or earlier, these are fairly useful, but on '05's and up, there's no point in them.

To vent the forks, the tanks are dismounted, held above each fork, and the vent valve opened. Then the fork should be bounced a few times to run any oil accumulated in the tanks back to the fork.

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  • Bigdong

Posted August 10, 2010 - 07:49 AM

#5

They are called "sub tanks". Their purpose is to increase the air volume in the fork so as to allow you to run more oil in it without the harsh feel you would usually get from doing so. If you have an '04 or earlier, these are fairly useful, but on '05's and up, there's no point in them.

To vent the forks, the tanks are dismounted, held above each fork, and the vent valve opened. Then the fork should be bounced a few times to run any oil accumulated in the tanks back to the fork.


that sounds like it , its an 03. thx again.


Edit:- if i wanted to take these off do i just need to unscrew them and replace with the screws or do i need to take some oil outta the forks?

Edited by Bigdong, August 10, 2010 - 11:52 AM.


  • grayracer513

Posted August 10, 2010 - 03:01 PM

#6

I have no idea how much oil is in the forks, or how long it's been there, and neither do you, so I recommend dumping and refilling.

To remove them, you simple unscrew the lines from the fork caps. What you replace them with depends on how they were installed. Some of the better ones had fittings that screw into the stock threads, which would let you use OEM vent screws and O-rings. Others require tapping the holes oversize, which means you'll need 1/8"NPT pipe plugs.

  • MrBlahh

Posted August 10, 2010 - 03:07 PM

#7

I thought subtanks were supposed to help in the woods too

  • Mr. Neutron

Posted August 10, 2010 - 06:05 PM

#8

That's where more than a few folks think they work best...... You can tune your fork oil level/air chamber to be soft & compliant on small trail stuff (roots & rocks...), yet still work well on things that give you a bigger hit. Most of the time, they come with a valve of some sort to regulate how much/how quickly the air from the air chamber in the open cartridge forks moves into the subtank. I'm certain I've seen more subtank setups in my woods riding than I have at the local mx track.....

They are a deal geared more towards open cartridge-type forks. My old 300 KTM with it's conventional 50mm forks would actually be a perfect bike for subtanks. Like Grayracer said earlier, they're not much good for the newer Yamaha closed cartridge-type forks ('05 KYB & newer???)......

Jimmie





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