wr400 overflow? Does it NEED one?

6 replies to this topic
  • jawknee21

Posted November 20, 2012 - 10:23 AM


So my friends converted to SM wr400 has no overflow for the coolant. It normally has one right? Apparently the PO or someone took it off and it just overflows coolant to the ground, Right in front of the rear tire. are there any other options for a replacement overflow bottle? How does it pull the extra coolant back into the radiators? If he fills the coolant it should overflow once and get to a normal level and not keep overflowing the rest of the coolant should it? What would that level be? Whats the procedure for making sure the bike stays cool but without an overflow?

  • William1

Posted November 20, 2012 - 10:33 AM


Do a forum search for 'Turkey Baster'.

Overflow amount is dependant on how hot the bike gets. Constant running over 20 mph, the coolant level once cooled, should always be just over the core (an inch or so below the filler neck). Slow speed running can boil most of it out, hence why WR's stock come with tanks.

  • jawknee21

Posted November 20, 2012 - 03:43 PM


so i can do the turkey baster mod like everyone was doing for a while on drzs? My drz has no overflow either so i'll probably be doing it on my bike soon too. The wr is ridden in traffic a lot right now and he doesnt split lanes yet. haha...

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  • William1

Posted November 20, 2012 - 05:15 PM


Yup. O f course, the res. does not have to be a baster but just with the 'plumbing/flow' being the same. The tank only needs to hold about six ounces.

  • jawknee21

Posted November 21, 2012 - 03:34 PM


so bottom hose of the res into the overflow and top of the overflow res vents to air. How does it pull coolant back into the radiator? the pressure? it always seems like it is a lot more than 6 oz but its probably just how it looks. thanks...

  • William1

Posted November 21, 2012 - 05:15 PM


Yup. It pulls it back in because as the engine cools, the coolant contracts, creating a vacuum. The radiator cap is like a two way valve sort of. It only needs about 1/4psi vacuum to suck air/coolant back in but 14~16psi to spit it out.
Your entire coolant capacity is about what, 22 ounces(time to check the manual)?

  • jawknee21

Posted November 22, 2012 - 12:11 AM


I havent gotten to ride my drz without the res bottle. I've been riding my other one which has one. The wr isnt mine so it hasnt been a priority to fix. I put up a WTB ad in the classifieds for a res for my drz though...


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