Stripped oil drain

999
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999
So I over-tightened and stripped the threads on my RM250 oil drain. Went to the auto parts store to try and find an oversize self-tapping plug. Checked three stores and none had the correct size but an employee talked me into trying a m12-1.75 vs the m12-1.25 that it takes. He said since its a bigger thread pitch it will cut new threads and should hold tight. Don't know why I listened to him but I tried it and it's still stripping. Now I'm stuck, should I try and find a double oversized m12-1.75 since that's what the threads are cut at now, or do I get it drilled out and have a hell-coil installed. If I installed a heli-coil would I use the m12-1.25 that it was originally, or the m12-1.75 that it is now? I don't have the tools or knowledge to do this myself so I will probably end up taking it to a shop, but I imagine that's going to be expensive so I figured I'd check here first and see what I should do.
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skypig
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skypig 7/15/2018 3:03am
7/15/2018 3:03am
Check this out:

http://www.timesert.com

The kit isn’t cheap, but comes with the drill and tap required.
I put one in a stripped fork leg on my Vintage RM125 (for the axle). Worked a treat.
1
Paw Paw 271
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Paw Paw 271 7/15/2018 5:39am
7/15/2018 5:39am
FYI: The case is very thin where the drain plug is located. It only has a small amount of extra material on the inside and if you drill it out you will be left with only the very thin part left and that is not enough to make the inserts hold. The insert will also extend further up on the case and not allow all the oil to drain.
The best fix is a new case and that is the only repair I would ever recommend.
How ever you can strip down the cases and take it to a welder and have the case welded, drilled and tapped for the plug. The issue there is the thin case material will most likely warp the case.

Paw Paw
alexk417
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alexk417 7/15/2018 5:42am
7/15/2018 5:42am Edited Date/Time 7/15/2018 5:45am
Stripped oil drain plug threads make me sick to my stomach. Good luck sir.

Edit: So my reply wasn't totally worthless. I would be doing what Paw Paw says and buying a new case or having it welded and tapped again.
kb228
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kb228 7/15/2018 5:55am
7/15/2018 5:55am
People fix this with helicoils all the time. As pawpaw said theres not much material there so it depends on the bike. Try it and see. Oreilleys has helicoil kits.

All you do is drill your hole out to the size the kit specifies. 2nd step is tapping the hole. Then use the helicoil install tool to twist the insert up in there. Its super eazy and takes 10 mins.

The Shop

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Paw Paw 271
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Paw Paw 271 7/15/2018 7:56am
7/15/2018 7:56am
Another issue with the thread inserts is that when you drill and insert them...They some times break off the little case material build up at that location and then you have a small chunk of case material moving in the transmission and that can cause issues down the line as it can jam a gear that can in turn break the case.

Paw Paw
coastlinecascot 7/15/2018 9:04am
7/15/2018 9:04am
Paw Paw 271 wrote:
FYI: The case is very thin where the drain plug is located. It only has a small amount of extra material on the inside and if...
FYI: The case is very thin where the drain plug is located. It only has a small amount of extra material on the inside and if you drill it out you will be left with only the very thin part left and that is not enough to make the inserts hold. The insert will also extend further up on the case and not allow all the oil to drain.
The best fix is a new case and that is the only repair I would ever recommend.
How ever you can strip down the cases and take it to a welder and have the case welded, drilled and tapped for the plug. The issue there is the thin case material will most likely warp the case.

Paw Paw
Always good info from you. Crazy I've done a couple dozen bottom end rebuilds and never paid attention to the thickness of the material there.
BobPA
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BobPA 7/15/2018 12:12pm
7/15/2018 12:12pm
Plenty of meat to put a timesert in place. You can buy them in all different lengths as well, this way the residual oil in the engine will be minimal. I have installed a bunch of them at our shop. The kits are $100, but it saves you a bunch over a new case.
overtheedge 7/16/2018 8:20am
7/16/2018 8:20am
Had a similar issue with a '06 KX450F that was a surprise from the previous owner (thanks!).

Similarly there was about a 1/4 inch of material, than a small basin, than more material above that. Timeserts seemed to be a good idea but I was nervous that material would collect in that small basin because the Timeserts are solid all the way through, which wouldn't allow all of the oil to drain out of the case.

Helicoils made me nervous because of the lack of material.

I ended up drilling what was there and retapping to the next bolt size, it worked great - err good enough to hold at least. However I did sell the bike a short time later as I was tired of dealing with all of these 'gotchas' from the previous owner.
Honda Man 66 7/16/2018 8:55am
7/16/2018 8:55am
JB weld the drain bolt in place and then drain the oil by removing the clutch cover. It is not ideal, but better than replacing the case half.
2
TrailDigger 7/16/2018 8:58am
7/16/2018 8:58am
Honda Man 66 wrote:
JB weld the drain bolt in place and then drain the oil by removing the clutch cover. It is not ideal, but better than replacing the...
JB weld the drain bolt in place and then drain the oil by removing the clutch cover. It is not ideal, but better than replacing the case half.
That’s a bandaid fix I’d expect to see on clapped out bikes on CL. I wouldn’t trust that and wouldn’t recommend it.

kb228
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kb228 7/16/2018 10:54am
7/16/2018 10:54am
Honda Man 66 wrote:
JB weld the drain bolt in place and then drain the oil by removing the clutch cover. It is not ideal, but better than replacing the...
JB weld the drain bolt in place and then drain the oil by removing the clutch cover. It is not ideal, but better than replacing the case half.
TrailDigger wrote:
That’s a bandaid fix I’d expect to see on clapped out bikes on CL. I wouldn’t trust that and wouldn’t recommend it.

x2. If anything split the cases, weld it up and re-drill & tap if you really want to do it right. JB weld is the redneck way of fixing anything. I dont even consider putting that garbage in my garage.
sandman768
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sandman768 7/16/2018 11:44am
7/16/2018 11:44am
My mechanic brother used to call me "Johnny over tighten "....I"ve stripped a lot of shit from being in a big hurry...nothing worse than striping center cases...I take my time, clean threads, use new crush washers & start all oil drain bolts by hand now....a good welder/machine shop get you sorted.... Have to split the cases though...
speed_racer
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speed_racer 7/17/2018 7:56am
7/17/2018 7:56am
Posted this before. Guy from Mexico showed me this and it works.

SOMETIMES you can use an american thread bolt or drain plug. The SAE threads are usually slightly larger than metric. Once you find the right size buy two of them and use a grinder to turn the bolt into a tap on the end. Put three flutes.
Make the bolt the actual tap and go slow, it will cut new threads and tighten strong.
mx317
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mx317 7/17/2018 10:45am
7/17/2018 10:45am
speed_racer wrote:
Posted this before. Guy from Mexico showed me this and it works. SOMETIMES you can use an american thread bolt or drain plug. The SAE threads...
Posted this before. Guy from Mexico showed me this and it works.

SOMETIMES you can use an american thread bolt or drain plug. The SAE threads are usually slightly larger than metric. Once you find the right size buy two of them and use a grinder to turn the bolt into a tap on the end. Put three flutes.
Make the bolt the actual tap and go slow, it will cut new threads and tighten strong.
If it's a 12mm, a 1/2 inch American is very close to 13mm (12.7mm) so that might work. Or just get a tap and tap it to 1/2" American.
Tracktor
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Tracktor 7/18/2018 3:15pm
7/18/2018 3:15pm
speed_racer wrote:
Posted this before. Guy from Mexico showed me this and it works. SOMETIMES you can use an american thread bolt or drain plug. The SAE threads...
Posted this before. Guy from Mexico showed me this and it works.

SOMETIMES you can use an american thread bolt or drain plug. The SAE threads are usually slightly larger than metric. Once you find the right size buy two of them and use a grinder to turn the bolt into a tap on the end. Put three flutes.
Make the bolt the actual tap and go slow, it will cut new threads and tighten strong.
I did this recently on a KTM that the owner had stripped one side drain bolt on. Can't remember exactly what sizes I used but wasn't really enough to Helicoil so went up basically a 1/2 size from metric to SAE and bought a good looking flange head bolt with copper washer. Tapped it out and worked great.........
lumpy790
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lumpy790 7/19/2018 7:21am
7/19/2018 7:21am
I have put in quite a few drain plug healicoils into customers stripped out bikes. I lay the bike on its side on a lift so it high enough to easily get to and work on.

When drilling and tapping I would put a air blower taped so its just blowing a little inside the motor through the crankcase breather hose so it blows the shavings out as you are taping.

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