00 yz 426

7 replies to this topic

Posted January 19, 2010 - 10:08 PM


hello all ive got a yz 426 2000 modle just done the head gasket as it was leaking heaps of water into the cylinder and comeing out the exhaust. i just chaged it put oil in and water and road it i road it for like 5 mins came home and it wouldent idel so i turned it off and left it for like 30mins maby an hour and all the water was gone from the radiator so i filled it up and tried to start the bike and again water comeing out the exhaust my question is y and could the head b no good or mayb something brakeing the head gasket i dont no im confussed and cant b bothered doing it all over again and again :bonk::banghead:


  • cwcarter

Posted January 19, 2010 - 10:12 PM


Did you check the cylinder and head surfaces to see if they are true?

Cylinder head warp limit is .05mm.

Are you using a torque wrench?

  • nor-calYZ426

Posted January 20, 2010 - 06:49 AM


Just did he head gasket on my 02 yz426 last night. You gotta make sure your head is not warped or it will just blow again. I took mine to a local machine shop and they checked it for free. You also need to make sure the surfaces have no old gasket material left stuck to them (took about an hour and a half to get mine looking good) when you put it together. Check the manual for all your torque specs and use a torque wrench. If you did all this and you are still getting water in the cylinder then you may have a cracked head.

  • Forddriver45

Posted January 20, 2010 - 05:31 PM


Mine did the same thing my old gasket started leaking so i changed it and it mad it a couple of hours and went again so when i changed it i put a lil hightemp gasket maker around the the water ports and triple check my torq. specs and i think i didnt torqe it enough the first go around i was in a hurry but all is well now.:banghead:

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed

Posted January 20, 2010 - 10:11 PM


ok guys checked the head today to see if it was torqued but in the process found that the back bolt on the head was loose not possble i made sure it was tight anyway i took it out to see wats going on the bolt is strpied bad i dident look over them when i pulled them out so im guessing it was already like that and thats wat caused the gassket to blow now is there anyway of checking if the thread is ok in the head if its no good wat can i do to fix this:banghead::banghead::banghead:

  • grayracer513

Posted January 21, 2010 - 09:20 AM


The thread is not in the head, it's in the crankcase. It can be repaired with a helicoil.


Posted January 23, 2010 - 05:12 PM


ok sounds like i may have to use a halicoil now another question will i need to get the piston put back in or will i be able to do it myself like will i need a ring comressor like you need on a 2 stroke not really a four stroke man this is my first and i aint likeing it lol well i like the way it goes when it goes lol

  • bill97gtp

Posted January 23, 2010 - 10:17 PM


yes ring compressor is required alwas use right tools for the job.

Related Content


BIGBORE FOR YZ450F 2006? by Taattie94

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 3 replies

Wilson the Blue Privateer by jetfuel

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  50 replies


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  30 replies

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.