coolant overflow issues

hey all,

when i recently motarded my drz i flushed out the coolant and replaced it all with some engine ice. i bled from the left radiator, and from the that bleeder on the front of the engine. i rode around and it filled up my overflow like 3/4 of the way.

i cooled it off, topped it off, but the issue is i keep having to do that. i seems either air is trapped and i'm just filling it wrong, or i'm overflowing and it aint going back in. one time i drained the overflow and topped of the radiator, but within 5 miles of riding it was back up to 3/4 full. i fear overheating or just plain dumping coolant out. i was on a 60mph left hand sweeper when the rear stepped out big time and i think it was from puking coolant :naughty: thankfully i avoided highside.

i've also noticed that after cool down, even days after, i hear a vacuum sound when opening the radiator. so maybe it can puke it but it can't suck it back up? bad hose or hose routing?

any guesses?



Have you tried bleeding the air from the bleeder bolt on top of the Rad?

Mike - :naughty:

Have you tried bleeding the air from the bleeder bolt on top of the Rad?

Mike - :naughty:

:naughty: After a quick re-read, sorry, I guess you did. no more guesses from me.

Mike -

yeah i tried bleeding twice when refilling. i'm more concerned that doesn't suck up the overflow and i get some kind of vacuum in the systems since i hear a whooshing sound when opening the next day when it is cool.

any other guesses :naughty:

could it be a faulty cap? are your running the kx 500 cap?

hmmm, that makes sense. what year kx500 cap should i get? i'm not keen on kx's and don't want to explode the parts counter moron's mind.

any one else think this is the cause or have any other suggestions?

i think you might be right tho.



I would guess cap too... or the return line is kinked, so that pressure from the rad is let through, but vacuum actually seals the kink more... ??

and yes, be careful around those parts counter guys, it can get messy when their heads explode

I got the box outside, I will get the part number for you later :naughty:

thanks! :naughty:

hold up,what mods to the motor?

thumper 440, but only their piston, not the sleeve. bored, nic plated and built by jesse. has yoshi cams, E base, still has acct, but from the ATV model. currently running S carb, and jesse airbox. jetting seems fine.

it has blown a head gasket or something before, jesse lapped the head to seal it again. i get no white smoke now or no idiot lights.

even when the bike has only run for 7 mins it can fill up the overflow, but it doesn't seem to be overheating. once it fills up to 3/4 or so i can't tell if it's dumping or staying in there. i think some might be dumping, but it's not like a huge amount. even after i stop non of it keeps puking.



head gasket leaking again.

have the head and cylinder check for straightness.on the new head gasket spray it with copper coat and let it dry.

use new head bolts.

ah crapola. so why does it not suck the coolant back in and create a vacuum in the radiators?



because its pressurizing the radiators.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By BikeChimp
      I'd like to turn my UK 2004 DRZ400S back to stock airbox (snorkel) and jets, needle shim position etc
      When I bought it the PO had fitted a Sigma6 kit and done the 3x3 mod but is doesn't have a tapered needle like the JD and other kits. Took me ages to get it running right, however it still runs rich and I'm fed up of arsing around with it. 
      So I've bought a standard airbox without 3x3 hole, stock exhaust.
      Q1 The Suzuki manual says this Mukuni BSR36 (29FA) carb should have a 142.5 Main Jet but the Clymer manual say its a 135.  In UK everything's from sea level to 1000m. I'm in Sheffield so nothing gets above 500m even in the Peaks (Hills). Any UK owners or anyone else know what the correct jet should be?
      Q2 Says the original needle is a '5DH36-2nd'. The needle has 5 notches on it. Currently set at 2 clip from bottom. The Suzuki reference says needle is 5DH36-2nd, Does the 2nd bit mean 2nd from top or bottom?
      Q3 - Does anyone have a detailed photo of the shim order just in case it was assembled wrong. (mine is attached)
      I know most people on here are going to be horrified I'm taking back to stock but any help on above would be really appreciated.

    • By Bgringo
      I've read a lot of threads about this but still haven't found exactly what I'm looking for.  I'm pulling my 2004 DRZ400S out of storage sometime this week and getting it ready for the season.  I live at 9,000 ft, but my first ride of the year is probably going to be at around 5,000 ft.  I was going to pull the 145 main jet I'm running and put in the 150 adjusting the needle from the 2 clip to the 3rd, then re-jet once I got home.  I already have the extended fuel mixture screw in place so I started thinking that I should just run the 150 jet set up and adjust the fuel screw to compensate for the higher elevation where I'll be doing most of my riding.  I will be going down in elevation for rides until late May or June depending on snowfall, but riding on the street when I'm able.  Are there any disadvantages with this?
      I'm new to posting on this forum, so please forgive me if I didn't get the right search words in and there is already a post about this.
    • By Markl5557
      I am currently running 10w 40 Belray non synthetic and I want to switch to full synthetic amsoil .... is it ok to switch from regular to synthetic? I have read it’s not safe to go from synthetic to regular can someone explain if it’s safe to go from regular to synthetic!? Thanks !
    • By RockyMtnMark
      Good Morning,
        Last night I measured my valve clearances for the very first time (I know...) on my DRZ400S.  It's a 2002 and I've owned is since 2011.  I bought it with t's got about 15,000 miles on it and most of it's miles these days are on dirt.
      Intake specs are 0.10-0.20 mm.  Exhaust specs are 0.20-0.30
      My intake valve clearances are in spec, forgot to write them down.  My exhaust valve clearances are between 0.1778 and 0.2032 which is slightly out of spec.  They are no more than 25 microns out of spec.  My question is, do I really need to shim these?  Will this kind of out-of-spec cause performance, mechanical, or other losses?  As far as I can tell, I'd have to buy a whole shim kit which is like $80.  Thanks!
    • By Zach440
      Selling my 2009 Drz400sm. Been a great bike but it’s time to let go . Not looking for any trades - spring is just around the corner ! Located in northern Virginia . Cash only $4200- willing to negotiate I have some wolfman luggage options available as well. Love to make a package deal for someone 

      -11640 miles . Mild off-road never wrecked.
      -Oil / filter changed every 1500 miles
      -New did chain , brake pads , front sprocket at 10400 miles .
      - valves checked and within spec at 10,000
      - jetted with JD kit and 3x3 mod
      -doubletake mirrors
      -waterproof usb wired and located next to Speedo
      - drc large foot pegs , barkbusters with integrated turn signals . 12oclocklabs tall delete with upgraded circuit board
      -thumpertalk case savers
      -sergeant seat (amazing) and Clarke 3.9 tank (190mile range )
      - fog lights wired in so they shut off with high beams
      -Shorai lithium battery
      -led headlight

      - stock gas tank and seat will be included

      The bike is dirty in photos and I apologize my water is currently disabled outside due to freezing temps . Radiator guards and skid plate NOT included but can be for some extra $$. Rear tire could be replaced but front is fine .