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mike73229 mike73229
2/25/2020 10:15 AM

Hi all, figured I'd post here for advice. 

My son stripped his trans oil hole on his '15 KX100 (same casings as KX85)

The bolt is snug but leaking for sure.

Ordered a new bolt and a 10mm/1.5 thread chaser/restorer. Hopefully those work.

If not, does anyone know if there's room to tap it to 12mm? I heard a helicoil/timesert aren't the best ideas there and hoping I don't need new casings obviously.

I saw pics on eBay of used casings p/n 14001-0681, to see what's inside and it's so hard to tell. The inside of the hole is definitely close to something but do I have 1mm all the way around to drill?

Thanks in advance!


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Jardo Jardo
2/25/2020 10:53 AM

Side note: Be careful searching the internet with the words "trans" and "stripped".

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kb228 kb228
2/25/2020 11:06 AM

Inserts are a common repair for that problem on all types of vehicles. They do work. As pawpaw comments every time in these types of threads, theres not a lot of material in that area. There may not be enough material to go to an M12 bolt.

The correct way to fix it is to split the cases and have the hole welded up and redrilled and tapped. Or buy a new set of cases.

Sometimes i wish the bike mfgs would install a key locking steel insert to prevent this problem in the first place.

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mike73229 mike73229
2/25/2020 11:13 AM
Jardo wrote:

Side note: Be careful ...more

Lol didn't see that one coming but so true

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AJ565 AJ565
2/25/2020 11:39 AM
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Paw Paw 271 Paw Paw 271
2/25/2020 2:25 PM
kb228 wrote:

Inserts are a common ...more


Paw Paw

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Zerofear66 Zerofear66
2/26/2020 6:55 AM

Definitely Timesert

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lumpy790 lumpy790
2/26/2020 7:36 AM

A timesert will require a much larger hole.

A Healicoil works great screwing a stainless steel insert into a smaller tapped hole

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mike73229 mike73229
2/26/2020 8:09 AM

Thanks all, going to try the chaser and new bolt this weekend. I think a heli coil will still require a bigger hole approximately the same size as a 12mm (10.7mm drill).

If the new bolt doesn't work, I think I'm going to drill/tap for an 11mm or 7/16 bolt. Can I use a standard flange bolt and crush washer since there are no oil pan bolts made in those sizes?

Worst case is drill/tap 12mm or heli coil or timesert

Worst worst case, new cases

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Paw Paw 271 Paw Paw 271
2/26/2020 8:22 AM

If you drill that large, pieces of the very thin case could very well break off inside the case. There is just not very much material there.
Also if you elect to do one of the other new thread patches you could have the same thing as well as creating a place for oil to hide when you change oils and the stock case has a smaller hole that is very low in the drain that will now be covered up.
Repair or replace the case is still the best fixes.

Paw Paw

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mike73229 mike73229
2/26/2020 8:54 AM
Paw Paw 271 wrote:

If you drill that large, ...more

When you say drill that large, will I be ok with a 9.5mm bit? That's all I need to tap for an 11mm bolt

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Momus Momus
2/26/2020 9:45 AM

Tap it to 7/16 unf with a greased tap. Much better fit than 12 mm.

10 mm is slightly larger than the recommended tapping hole size but will work well. Seal the threads with a non hardening goop.

If the glass is half full it's twice as big as it needs to be.

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mike73229 mike73229
2/26/2020 10:08 AM

Thanks Momus!

Here's what my options are

...................................................... Drill bit size converted to mm
A. 10mm x 1.5 stock.........................8.5mm
B. 11mm x 1.5..................................9.5mm
C. 7/16-20........................................9.9mm
D. Helicoil for 10mm x 1.5.................10.3mm
E. 12mm x 1.5 standard plug............10.7mm

E is out I think. If Plan A fails, going to try B or C but will have to use a flange bolt from hardware store as a drain plug.

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Paw Paw 271 Paw Paw 271
2/26/2020 1:00 PM

Don't put a bandaid on the issue.....Fix it correctly. Remember that if your fix fails it could cost some serious injuries...

Paw Paw

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Momus Momus
2/26/2020 8:15 PM
mike73229 wrote:

Thanks Momus!

Here's what ...more

You are not listening.

I've done this case save repair job many times over the last 45 years.

Use 7/16" unf.

If the glass is half full it's twice as big as it needs to be.

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mike73229 mike73229
2/26/2020 8:31 PM

Yeah I realized there's no 11mm bolts anyway. I ordered everything I need to do the 7/16-20 (unf). If I do it right, you nailed it - case save indeed!


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theDogger theDogger
2/27/2020 8:58 AM


Dont need to spend that much $$$ I have used these on Showa and KYB fork lugz that are stripped for the lower protectors

Search for HeliCoil and there are small kits you can buy for like $20


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Scrambled Scrambled
2/28/2020 5:48 AM

There are companies out there that specialize in drain plug repair bolts. A couple of years back I was looking for something for my Honda CR125 and found a company that made 1mm oversize with the same pitch, which means you could just chase the old thread through with the tap that came with the kit. I've just had a quick look and can't find them, but if you search you might find something. The other option is a tapered drain plug repair bolt. Both are much easier than an insert or drilling and re-tapping I would think.

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mike73229 mike73229
2/28/2020 6:59 AM
Scrambled wrote:

There are companies out ...more

Thanks for looking, I appreciate that. I did research and there was nothing for a 10mm oversize, just too small to market I guess. As far as the tapered ones, I looked into those too and again, they are intended for a bigger hole, so they would stick out pretty far in a 10mm and could still leak since not as many threads seated.

I am set to go with the 7/16 drill/tap and hopefully end up with as good as new solution.


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mike73229 mike73229
3/8/2020 5:03 PM

Well, I thought I'd report back. I successfully fixed the problem so hopefully this post helps others in the future. 

I confirmed first that the 10mm hole was not salvageable. The new 10mm bolt was not able to be torqued properly either before or after chasing the threads with a thread cleaner (not a tap)

I drilled with a greased 25/64" bit, called for to tap a 7/16-20 unf thread. This step may not have been necessary but there was metal on the bit so I feel like the hole was cleaner to tap. Very little drilling was necessary, just in and out on low speed.

Next I tried to use a Gator tap block but it was too big to fit between the frame and casing so I cut a small square from a 1x2 block of wood, and drilled a proper hole to use as a tap block.

I then used a T-handle tap wrench and generously greased 7/16 tap. Backing out every now and then I made it through and backed out. 

I flushed a couple of quarts of clean oil through and then with a copper washer, torqued the new 7/16 bolt a little at a time until torqued to spec.

I am not sure the tap block helped me to go in 100% straight, but the copper washer and bolt flange look flush and I haven't seen even a drop of oil or wetness 4 days after running the bike several times.

Cost of repair, was 1 tap and wrench, 1 drill bit, and a bolt and washer.

Thank you all for the detailed advice, I may not have succeeded without it! (and no helicoil to worry about coming out)


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