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Oil drain bolt torque spec - snapped bolt. Throttle question also.

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Question 1-

Ok so Im going to glamis for the first time april 2nd. Only have one ride on this bike since I got it from the dealer used.

Figured since il be spending three days out in the dunes I should change the oil -- didn't know when it was changed last.

Well everything goes smooth up until I go to torque the left engine case drain plug in. I set my wrench to 18NM as the manual said 20nm. (im using an 08 book on 07, should still be the same right?) Well what do you know it snaps the bolt head off and leaves the threaded part in the case. Why the hell would it snap off if I was below torque spec?

So I'm going to ez-out it and replace it hopefully before april 2nd. What would the shop charge to do this do you think? Even though I would hate to do this, do you think since its torqued in there it might be fine to ride on if it doesnt leak?


Question 2-

On neutral/idle, when I snap the throttle from 0-full it dies. I heard this is normal but is it?


2007 yz450F

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On question 1.

No it's not OK to leave it there. A bolt stays tight because of the tension between the threads pulling down on the bolt head. Without the head, the shank of the bolt is no longer torqued at all. It's just laying in the threaded hole.

One reason I cringe when people start using torque wrenches on drain plugs instead of common sense is that they bypass one of the basic principles involved with torque specs. Unless the text specifically states that the threads are to be oiled or lubed, all torque specs are given with the assumption that the threads are to be clean and DRY. $5 says they weren't. Then when you ran it down to 20Nm, the actual tension on the bolt was closer to what you'd see at 35 than 20. User error. Have your wrench tested anyway.

A shop will probably charge an hour's time for the screw extraction.

On question 2, yes, it's normal. No one who knows how to ride rides that way, so it shouldn't be a problem for you.

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As Gray mentioned...when the head of a bolt has been broken off there is no tension remaining on the threads. In most cases...as long as the bolt isn't cross threaded or have any lock tite on it, you can remove the broken bolt with a pick and some patience. If that is unsuccessful next I would try a left handed drill bit before breaking out the eazy outs or the cash to have it extracted. Normally about the time the bit starts to drill...it unscrews the remaining part of the bolt, problem solved.👍

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Yeah it's the first time I have done an oil change on the 450 so I was going by the book. I usually don't whip out the torque wrench but I figured I would just to make sure I did it right. Ironically thats what screwed me.

Does anyone know what size the bolt is? I have to get a new one now obviously. I just hope my threads are fine.

And yeah I don't snap the throttle open while riding so its never happened during a ride, but i noticed it today when it was in neutral. Figured I'd run it by you guys to make sure.

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Hey thanks for the help!

I got the bolt out with a bit of fighting with a drill bit and a flat head screwdriver. I pulled a couple half moon shavings out of the threads as well. I dont know if that was part of the bolt threads or the case threads.. but the new bolt went in and I got it up against the case. Im afraid to tighten it too much to where it breaks the threads again. Would loctite or something like that be ok to use? I really dont want it coming loose out in the dunes.

Also when I had the bike laying on its side I noticed oil coming out of my right fork tube by the lower "triple clamp" or w/e that is. 👍

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Hmmmmmm good question, I didn't even think about that. That had to be it then because I can't see how it would be fork oil.

I'm going to get the bike p on a stand and shift from 1st to 2nd and see if the bolt leaks. I idled it in neutral and revved it but it didnt leak so hopefully im good to go.

edit: Did the above and it shows no sign of leaking so I think she's fine!

Edited by Sheridan450F
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