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ArmyRider90

How do you change head gasket? 2003 YZ450F

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I have an 03 YZ450F and it has a blown head gasket, I have never replaced a head gasket before and was wondering if anyone had a link or could give me some detailed instructions, I would really appreciate it. The motor was just rebuilt and has 5 hours on it, but it blew the new one. Is there anything I should know or any tipds would be great, thanks alot.

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Get a service manual. It will guide you through the whole process. One thing to pay very close attention to will be the gasket mating surfaces on both the head and cylinder. These surfaces need to be perfectly flat. Also the torque sequence of the Yamaha is a little unusual but works very well. It covers that in the service manual too.

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I have an 03 YZ450F and it has a blown head gasket, I have never replaced a head gasket before and was wondering if anyone had a link or could give me some detailed instructions, I would really appreciate it. The motor was just rebuilt and has 5 hours on it, but it blew the new one. Is there anything I should know or any tipds would be great, thanks alot.

Sounds to me like the head is warped (or very poor assembly during the rebuild)... i'd suggest having the head an cyl checked for warpage, or you will be pulling the top end apart again in another 5 hours...

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...or very poor assembly during the rebuild....
The head bolt torquing procedure is an angle torquing process, and failure to follow the instructions, which happens all too often, can result in a failed gasket quite easily. This includes the failure to lube the bolt threads at least at the start of the process.

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