yz 400 rattling

3 replies to this topic
  • yamaha2004r6

Posted December 21, 2008 - 07:52 AM


hi i hope some one can help :smirk: i have a 1998 yz400f which is making a clanking noise from the left side of the engine. It is quite loud and erratic and not a constant rattle you can hear it when idling standing still and when you ride it. It starts just fine and pulls really well.

Does any one any ideas many thanks.........:thumbsup:

  • ml795

Posted December 21, 2008 - 07:55 AM


probably the timing chain. check the tensioner to make sure it's working properly.

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  • yamaha2004r6

Posted December 21, 2008 - 08:35 AM


sorry mate how do i do that??

  • grayracer513

Posted December 21, 2008 - 09:15 AM


YZ400's, like the rest of the YZF family, are noisy. What you here may be normal.

However, to check the chain tensioner, position the engine at TDC on the compression stroke with the cam cover off, and see if the chain is tight. It should be. Then remove the bolt in the center of the tensioner, and using a small screwdriver, turn the center shaft of the tensioner 1/4 turn clockwise. There will be resistance from the spring, but it turn freely otherwise. When you release pressure on the screwdriver, the shaft should snap back to its original position.

'98-'00 YZ 400/426 models used a straight key to anchor the balancer shaft drive gear, which is located on the right side of the engine behind the primary drive gear. It is not uncommon for the primary gear nut to loosen, causing the balancer gear to rattle on the key. This will beat up the crankshaft if allowed to continue, so you should check it and replace the key if you find it loose.

If you need a manual:


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