I screwed up

Tonight I was changing my oil on my '07 WR 450 as usual and mistakenly over torqued the left side case drain bolt which I believe stripped the threads. Is there any fix for this?

Do not worry, not all is lost! You have a couple options (I bought a bike with this very issue. Yz 450 same year) you can either tap out the hole to the next size up (using precision and going slow) or you could tap to the next size then helicoil it back down to the original plug size. A couple things to consider:

don't over drill when drilling out for the tap. You will start to hit stuff inside the case.

Try not to get many metal shavings in the motor, although as they are aluminum they should not damage anything. Put grease on drill bits and taps and clean and replace grease often while drilling

Helicoils tend to make the bike drain pretty slowly. And the metal part that gets bent back/snapped off when installed CANNOT go into the motor! You cannot let it! This is stainless steel, and will lunch the engine!

I strongly advise going up to the next size of bolt, get a bolt from the store that matches the other bolts length exactly. The cases have enough meat to go to the next size up without causing issues.

Last but most important:use a torque wrench as you obviously don't have the feel for these bolts yet! The YZ/wr is a long threaded case. It's one of the more difficult bikes to strip out that bolt.

I prefer the Time-sert threads over the Heli-coil. The time-serts are a steel insert instead of a coil and there is no little tang to worry about. When you drill the case go slow and cover your drill bit and the tap with grease. That will help to keep most of the metal shavings out of the case. Once you have the new threads installed and before you put oil in it I would flush some clean mineral spirits through to get out as much of the debris as you can.

Thanks a bunch. I'll let y'all know how it goes.

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