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I recently purchased a 2014 KLR 650. I was tightening the oil drain bolt, aftermarket Tusk magnetic bolt, to 21 ft-lbs when the bolt fractured in multiple places at the head. The threads don't appear to be stripped, and there aren't any cracks in the crankcase. I looked up into the the drain bolt hole and noticed that the threads have a downward v-shaped tapered opening to them near the top when looking up and to the bike's right side. Is this how the threads are manufactured? Is it for oil flow when draining, or could I have broken a piece of the upper threads? Any knowledge would help to calm some fears.
 

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I'm not sure exactly what you're referring to; pics would help but you need to have a min number of posts to post a pic (to stop spammers).

2 things,

From my list of "Top KLR Owner Mistakes", right at number one:

1) Oil drain plug overtightening: it is relatively common for people to overtighten the oil drain plug.....usually to stop a leak after the gasket/washer has inadvertently fallen into the used oil or left stuck to the bottom of the engine! best case is stripped threads, worst is a cracked case. Make sure the washer is in place and use a torque wrench Note; my manual says 17 ft lbs, Eaglemike recommends 15 ft lbs with his low profile drain plug which is what I use. Some Gen2 manuals specify 21 ft lbs but there has been no change in the plug or case which would affect the drain plug torque and people have stripped their drain plugs at this setting: beware!


and secondly, the Tusk pce is known to break; go with Eaglemikes low profile plug. Eagle Mfg & Eng


Dave
 

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I think that's exactly what I was seeing from the underside. Thought I had broken a chunk off the threads like a complete noob. I've ordered an OEM bolt, and will use a lesser torque setting in the future just in case. Thank You.
 

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I was always taught that the proper way was to tighten it til it strips and then back it off half a turn. surprise:. It's shocking how often I still follow that advice ;-).

Note to the literal minded; DO NOT DO IT THIS WAY!
 

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I don't use a torque wrench I just tighten it up until just before it strips LOL

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I was always taught that the proper way was to tighten it til it strips and then back it off half a turn. surprise:. It's shocking how often I still follow that advice ;-).

Note to the literal minded; DO NOT DO IT THIS WAY!
I really kind of wish that people wouldn't joke about this issue, but hey that's just me.

What I really wish, would be for all the manufactures of motorcycles and other engines to do, would be to use a smaller drain plug in the first place. With enough material around the original drain hole size to re-tap at least 3 times larger.

The stripped 12mm X 1.5p KLR650 drain can be most readily tapped to 14mm X 1.5p.
The problem is, with a bigger head on the bigger drain plug the next owner will attempt to Tighten IT Even Tighter!

If the drains were to start at 8 x 1.25 next up could be 10 x 1.5, next up could be 12 x 1.5 (which is current standard), then 14 x 1.5!
 

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I was not joking. I guess what I'm really trying to say is over the course of 35 or more years of wrenching you kind of get a feel for things. I can always tell when a bolt is about to strip because it is no longer getting increasingly harder to turn. I have never used a torque wrench in my entire life. I have had dozens of machines and never stripped a drain plug. I have also never lost a drain plug. Partly from luck and then later on from sheer experience. As far as other bolts snapping them off is my specialty LOL actually a friend of mine has a new Ducati motorcycle he followed the manufacturer's instructions using a torque wrench on the oil drain plug and stripped it before reaching the recommended torque. It is things like this that make me glad I have a feel for it. My general rule for drain plugs is make it snug and then go a quarter turn

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Not the first time I've posted this, but . . . sometimes, an OVERSIZE OIL DRAIN PLUG offers a permanent fix to stripped sump threads.

The tapered, self-tapping slightly-larger diameter oversize plugs essentially re-tap the oil drain hole upon first insertion.

If the oversize plug doesn't seal, then . . . look to drilling-and-tapping/insert/welding and re-threading/etc. Worst case, trick "temporary" plug, like an expandable motorboat transom plug, flapper, etc. A proper oversize plug costs maybe $ 3 or so; M12-1.5 oversize plugs available from the Internet; MAY be on-the-shelf at your friendly local auto parts store. M12-1.25 more common, and may even work. I'd favor chancing M12-1.5, in hopes of rehabilitating the original threads.

DISCLAIMER: No offense intended toward those who run, screaming, from the room at the thought of an oversize plug (vs. other remedies). I've had "miracle cures" with them, and . . . factories are working nights manufacturing them; some successful application and use must come from oversize oil drain plugs.

----------------------

Ain't never tried it, but . . . drilling-and-tapping for a 1/2" replacement plug might work; a 1/2" diameter might be just slightly larger than the stock 12 mm hole . . .
 

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I really kind of wish that people wouldn't joke about this issue, but hey that's just me.
pdwestman, I didn't mean to irritate anyone here, but yes, I was joking. Being a professional mechanic (albeit not motorcycle) for well nigh 40 years, I have to laugh at some of the turns (insert pun here) that the job takes. It's that or go insane. A sense of tragic humor and appreciation for the perversity of machinery sure comes in handy once in a while ;-). It's no laughing matter if it happens, but I'd rather laugh and carry on than rage and start to throw things, or start sobbing gently. It wasn't my intent to make light of what can be a serious matter. Sorry.
 

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Ghost Rider & Liftrat,
I am not irritated, only saddened.

As a professional mechanic for over 41 years also, I can not ever remember using a torque wrench on a motorcycle oil drain plug during a normal oil change.

But I have used the torque wrench set at about a pound or 2 low, to snug a plug on the gasket 'snug enough'. Then hand the customer a 6 inch handled wrench and tell them to pull it 'Just A Hair Tighter', so they can feel the crush gasket 'crush' just a hair more!

This is usually after finding a crush gasket CRUSHED to Death and rolled around the flange area of the drain plug. The next step from CRUSHED to death is STRIPPED out hole!

Many of us older/higher mileage riders which have always serviced our own engines got our "Stripped out drain hole" training on $50-100 lawnmowers, instead of $6000+ motorcycles. :)
 

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Non mechanics Non torque wrench feel varies for 18ftlb prob about 10 ftlb. Its ok for us guys who have been in the industry (and probably stripped a few cases) to understand what a certain torque feels like. But try and tell a newbie he should by a quarter drive torque wrench? Too hard.
 

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I'm not a professional mechanic but I have had 39 bikes over 42 years, rebuilt/restored several vehicles and spent some time working in the automotive industry and I still use a torque wrench. Despite my experience, I am still far more comfortable taking the extra 30 seconds to use a decent torque wrench on critical fasteners........I'm probably fairly close using my "best guess" but the KLR has several fasteners that will strip out at torque levels that aren't that far off the spec (actually some can strip at the specified torque).

I'm comfortable enough that I don't take a torque wrench out on the trail but if/when I do make a trailside repair or adjustment, I'll re-torque the fastener when I get back to my shop.

My WAG is that even the most experienced mechanics will have a hard time getting within 10 - 20% of the specified values. YMMV


Cheers,
Dave
 

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And when we or they happen to Error 20% Over the Specified Value, that can be the 1st stripped threads or broken bolt!
 
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Stripped oil drain bolt hole repair consideration:

Saw on another forum; someone used a 1/4" NPT pipe plug, after tapping to that size.

Don't let the 1/4" nominal size throw you; NPT threads are listed based upon the INSIDE DIAMETER of the pipe to which they relate; the OUTSIDE DIAMETER of 1/4" NPT fittings is about 1/2"; slightly larger than the 12 mm oil drain hole.

The NPT approach might work where an oversize oil drain plug won't; the NPT plug is tapered, just might work!
 

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A 'tapered' National Pipe Thread plug will work, until the 1st person over-tightens IT, even just a 'little' in the thin, brittle, cast aluminum motorcycle crankcase.

Then it will split the boss and make a Crack! How wide of crack depends on how much TOO Much one screws in the tapered NPT plug!
 

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the taper and the pressure it could potentially apply to the weak case would be my concern also; a stripped hole is bad enough, a cracked case is a whole order of magnitude worse!

2 cents,
Dave
 

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Stress from a tapered NPT plug would come only from the TORQUE applied, seems to me. Crankcase is vented to atmosphere; no hydrostatic pressure involved, I would think.

But, I could be wrong--cases could fail upon the insertion of a NPT plug, for all I know.

Oversize oil drain plugs are tapered also; unsure of the degree of taper in comparison with NPT plugs.
 

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Stress from a tapered NPT plug would come only from the TORQUE applied, seems to me. Crankcase is vented to atmosphere; no hydrostatic pressure involved, I would think.

But, I could be wrong--cases could fail upon the insertion of a NPT plug, for all I know.

Oversize oil drain plugs are tapered also; unsure of the degree of taper in comparison with NPT plugs.
Yes, my concern is the taper forcing the weak case to crack. ....and the OS drain plugs taper is the reason I consider the "best" fix for stripped oil threads as drilling and taping for a larger size (non tapered) plug.

2 cents,
Dave
 
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