Help - What is this hole for?

4 replies to this topic
  • anoldsman

Posted June 22, 2011 - 10:53 AM


I recently purchased a 1998 WR400F that had low compression. The bike already had the tank, plastic, and carburetor removed. I removed the head and cylinder to find a stuck ring. I am in the process of putting it back together when I noticed a hole on the right side of the head centered just above the combustion chamber surface. Here is the picture. Any ideas on what it is for?
Posted Image

  • dgcars

Posted June 22, 2011 - 10:55 AM


This allows the spark plug recess to drain

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  • Sknight

Posted June 22, 2011 - 12:03 PM


Yep. Make sure it's clear while you have it easy to get to.

  • MANIAC998

Posted June 22, 2011 - 07:02 PM


Yup! It's just so you can blow air in there before removing the sparkplug to keep any debris from finding it's way into the combustion chamber. Maniac

  • anoldsman

Posted June 23, 2011 - 06:11 AM


Thanks for the help guys!!!


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