yz400f cracked head

4 replies to this topic
  • tjr_84

Posted January 02, 2011 - 09:39 PM


when i got back for riding the other day i notice i have a cracked block, can i remove the head without pulling the motor?? and does a 426 head fit the 400?

  • Birdy426

Posted January 02, 2011 - 11:01 PM


Yes and yes...but are you sure it's cracked? to a water jacket? to the combustion chamber?

Note that to run the 426 head, you will either have to use a 426 carb with internal hot start or drill the boss inthe intake tract and press in a nipple for a vacuum source for the external hot start on the 400.

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  • Kawidad

Posted January 03, 2011 - 09:08 AM


Or don't worry about having a hot start. But, bear in mind if you switch to a 426 head the cranks are different too.

  • tjr_84

Posted January 03, 2011 - 10:04 PM


the head is cracked from the water jacket to the out side i can see water weep out the crack by the head bolt

  • matt4x4

Posted January 06, 2011 - 05:20 AM


switching to a 426 head has absolutely no impact on the crank. :smirk::bonk:B)
If the head is cracked on the outside you can likely have it welded by a competent welder, it'll save you much $$$ and time.


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