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Stripped the oil plug thread

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After over tightening my oil plug I stripped the thread out :bonk: (insert expletive here).

So now there's only one thing for it. Drill out, re-tap and heli-coil. Seems straight forward enough.

My first question is; am I in any danger of doing damage to any components by drilling the hole with out taking the engine apart, or even out of the frame?

I intend to do it by hand with the engine still in the frame using a block of would to check the drill bit from going in any deeper than it needs to.

After it's drilled, tapped and heli-coiled I will flush white spirits or kerosene through a few times to wash out any bits that may be inside.

My second question is; will this be sufficient to properly clear the bits of aluminium out of the case? If I miss any bits, how dangerous is that too the engine? Since its only aluminium, I'm guessing it won't be a major if a couple of bits are left in there, but thought I'd better ask.

I would split the cases but really don't want too. I have no gaskets and the local parts store is slack, expensive, and won't have them here for me in time to ride next weekend.

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Your on the right track with everything you said. I helicoiled my motor in the frame and it worked well for a while but soon the "spicot" part that sticks out of the casting cracked when I tightened the bolt because of the material lost from helicoiling. I fixed it right by getting a case off ebay.

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Forgot to mention before, I'm also considering drilling, re-tapping, and then rather than go with a heli-coil, just machine up an oversize plug.

Your on the right track with everything you said. I helicoiled my motor in the frame and it worked well for a while but soon the "spicot" part that sticks out of the casting cracked when I tightened the bolt because of the material lost from helicoiling. I fixed it right by getting a case off ebay.

Just had a look at the parts store on TT, at $565 for a case, I think I'll try make the heli-coil or oversize plug work. The new case will be an absolute last resort.

Edited by kiwi86

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Forgot to mention before, I'm also considering drilling, re-tapping, and then rather than go with a heli-coil, just machine up an oversize plug.

Just had a look at the parts store on TT, at $565 for a case, I think I'll try make the heli-coil or oversize plug work. The new case will be an absolute last resort.

If you are able to find or make a slightly oversized plug I think that is a perfect solution.

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If you are able to find or make a slightly oversized plug I think that is a perfect solution.

Sweet, will definitely try that.

What about the swarf from drilling/tapping? will flushing with spirits be enough to clear it? Will any bits that I miss cause any drama? This is my main concern.

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Try to get your hands on a timesert. They're superior to a helicoil. I just did one and it worked great.

Whichever method you go with, when you drill and tap, put grease on the drill bit and tap. It will make a lot of the shavings stick to the grease. After you drill and tap, put a shop vac up to the drain hole. It might help to have the fill hole opened while using the shop vac on it.

http://www.timesert.com/index.html

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The quickest and cheapest repair is go to local auto parts store buy one of the rubber expanded plugs made for stripped drain holes stick it up in the hole and tighten/expand the rubber seal until it seals. Having a skid plate is better to protect the plug from being damaged though as the plug can be physicaly torn out of the hole if struck.

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Okay, everybody knows there is a washer that goes between the case and the drain bolt, right?

I've seen soft steel washers and copper washers, but I prefer nylon or fiber ones -- just something to help create a seal.

The reason I ask is that I've seen a few bikes without washers and guess what... the drain bolt was overtightened and stuck.

And you shouldn't have to tighten the crap out of the drain bolt to get it to seal, correct? Seriously, a fresh washer and GoodandTight is all you need.

If you're really worried about the drain bolt droping out, buy one with a hole in it and safety-wire that rascal.

The number of "Drain bolt stuck" threads is crazy, and it doesn't have to be this way.

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And you shouldn't have to tighten the crap out of the drain bolt to get it to seal, correct? Seriously, a fresh washer and GoodandTight is all you need.

If you're really worried about the drain bolt droping out, buy one with a hole in it and safety-wire that rascal.

Exactly.

Don't overcomplcate things... forget the thread inserts entirely, they just cause problems for most people because they are using hand drills, etc to install them. If you disassemble the engine, strip the case down bare and drill / tap the hole in a drill or mill, a thread insert is the best fix.

-Buy a tap 2mm larger than the original size.

-Buy the correct drill bit for the tap you use.

-Cut a length of PVC pipe (probably 3/8" or 1/2") to use as a drill stop and slip it over the drill bit. (cut it nice and square)

-Be very careful when you drill... make sure you don't wobble or change the angle.

-Tap the new threads

-Install the oversized drain bolt with a sealing washer and a light touch.

If you are saving $100-$500 on a replacement case, spending the money on a proper drill & tap seems well worth it.

Most of all, take your time and be precise.

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Try to get your hands on a timesert. They're superior to a helicoil. I just did one and it worked great.

Whichever method you go with, when you drill and tap, put grease on the drill bit and tap. It will make a lot of the shavings stick to the grease. After you drill and tap, put a shop vac up to the drain hole. It might help to have the fill hole opened while using the shop vac on it.

http://www.timesert.com/index.html

That's a nice thread insert. That looks vastly better than a helicoil. If you can find one of these, I would re-consider my previous comment.

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Did the same thing on my KX250F and I was able to use helicoil will out tearing engine down. I measure how far in the drill bit needed to go and taped that length on the drill bit from the helicoil kit. I laid the bike on its side and drilled out the hole once the plug was out. Thread in the helicoil so it is just past the first thread to the case bottom. Be careful when you bust off the end of the helicoil because that is hardened steel and you do not want that in your engine. To help keep the helicoil piece from falling in the engine make sure you stand the bike back up and break that piece off with some skinny needle nose pliers. Make sure you do not loose that little piece when you break it off. I never had a problem with my drain plug again. Your right about the aluminum that may get in the case it won't harm the tranny but to help get any that may get in just purge it out with some motor oil with the drain plug out.

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Try to get your hands on a timesert. They're superior to a helicoil. I just did one and it worked great.

Whichever method you go with, when you drill and tap, put grease on the drill bit and tap. It will make a lot of the shavings stick to the grease. After you drill and tap, put a shop vac up to the drain hole. It might help to have the fill hole opened while using the shop vac on it.

http://www.timesert.com/index.html

Ok, the grease sounds like a good idea, will definitely try that.

The quickest and cheapest repair is go to local auto parts store buy one of the rubber expanded plugs made for stripped drain holes stick it up in the hole and tighten/expand the rubber seal until it seals. Having a skid plate is better to protect the plug from being damaged though as the plug can be physicaly torn out of the hole if struck.

Never heard of these, I might get one as a handy keepsake if something like this ever happens again. Hope to have a proper drain plug machined up before next weekend though.

Okay, everybody knows there is a washer that goes between the case and the drain bolt, right?

I've seen soft steel washers and copper washers, but I prefer nylon or fiber ones -- just something to help create a seal.

The reason I ask is that I've seen a few bikes without washers and guess what... the drain bolt was overtightened and stuck.

And you shouldn't have to tighten the crap out of the drain bolt to get it to seal, correct? Seriously, a fresh washer and GoodandTight is all you need.

If you're really worried about the drain bolt droping out, buy one with a hole in it and safety-wire that rascal.

The number of "Drain bolt stuck" threads is crazy, and it doesn't have to be this way.

Yep, It had the washer on it that looks like aluminium as well, I will see about a rubber one to replace it.

Exactly.

Don't overcomplcate things... forget the thread inserts entirely, they just cause problems for most people because they are using hand drills, etc to install them. If you disassemble the engine, strip the case down bare and drill / tap the hole in a drill or mill, a thread insert is the best fix.

-Buy a tap 2mm larger than the original size.

-Buy the correct drill bit for the tap you use.

-Cut a length of PVC pipe (probably 3/8" or 1/2") to use as a drill stop and slip it over the drill bit. (cut it nice and square)

-Be very careful when you drill... make sure you don't wobble or change the angle.

-Tap the new threads

-Install the oversized drain bolt with a sealing washer and a light touch.

If you are saving $100-$500 on a replacement case, spending the money on a proper drill & tap seems well worth it.

Most of all, take your time and be precise.

Thread inserts are my second choice, I'll stick with the oversize plug. As for the drill and tap, already got that, so will be saving plenty.

Did the same thing on my KX250F and I was able to use helicoil will out tearing engine down. I measure how far in the drill bit needed to go and taped that length on the drill bit from the helicoil kit. I laid the bike on its side and drilled out the hole once the plug was out. Thread in the helicoil so it is just past the first thread to the case bottom. Be careful when you bust off the end of the helicoil because that is hardened steel and you do not want that in your engine. To help keep the helicoil piece from falling in the engine make sure you stand the bike back up and break that piece off with some skinny needle nose pliers. Make sure you do not loose that little piece when you break it off. I never had a problem with my drain plug again. Your right about the aluminum that may get in the case it won't harm the tranny but to help get any that may get in just purge it out with some motor oil with the drain plug out.

That has me worried, and is the main reason I want to stay away from thread inserts

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