02 Yz426 rattle

So I bought this mostly stock YZ to take lessons on the track and am wondering about this rattle it makes. I made a couple You Tube videos with the noise. Let me know what you think it is.

One video is of me kick starting it and it rattle two times - once in the middle and once at the end of the videos.

The second video is of it running and rattling after shutting it off.

Please let me know your thoughts on what this may be or what to check. Timing chain is tight, valves are within spec., and it doesn't have any blow by or eat oil. Wacky.

My other two bikes were XR400 and currently an 08KTM530EXCr.

Thanks guys,


Pull the clutch-side cover and check the primary drive nut.

Ouch! That is not what I wanted to hear. Just to get to it I have to take a part the clutch and oil/water pumps. Yikes. I will do it though. I will have to borrow a torque wrench I suppose.... Thanks. I will post if that is what is rattling.

Not that big a dealio. You don't have to take the clutch apart, nor do you have to take the waterpump off the cover. You DO have to drain the oil and coolant, and take the brake pedal loose.

Phew! Done... Checked the primary gear nut and it was all solid. Buttoned it back up and put in fluids. No change. I did notice that the kick start lever bolt was loose. Tightened that too. I guess I will ride it until it breaks and let you know what it was.

-Take care

Wow! I don't think I'd run it till it breaks. Things like that can get really costly, quick!!! Do what you want though. Maniac

You're right of course, Maniac. My frustration at solving the mechanical issue was causing me to be overly dramatic. I am going to take it to a couple desert racers I know who are not dealers but own WR's of the same year and see what they say. Please continue with ideas of what this mystery rattle could be.

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