1985 atc 250r: How much room do I have to re-tap my oil drain plug?

[k00leo]

Ok, this is pretty bad here. Oil drain plug is stripped.

12mm and 14mm are too small.

16mm is too big.


The previous owner had a 9/16 bolt in there. It wiggles around and doesnt catch the threads. So 9/16 is a little too loose.


Here is what i'm thinking, 9/16=14.28mm, so i would think a 15mm would work, but i cant find any in my area. So, Im thinking that 5/8 would be the appropriate super over size right? 5/8 = 15.87.


Question is, How much room do i have to retap my oil drain plug? Will a 5/8 re-tap be too big ? Im basically drilling into a small collar right?


I'm might take it to a shop, but i want to gather as much information i can before i go there.

[Dirtcrasher]

.625 is pretty big. Does a timesert or helicoil still work in that hole? A threaded insert (timesert or similar) may be better for that large a hole.

Unfortunately, I believe the shift cam is right above that drain plug so it's tough to drill being that a drill is pointy on it's face. I've used flat faced end mills before.

It's aluminum, if the existing hole is just .010 thousandths too small for the timesert or helicoil tap, I'd just slowly tap it and be sure you are 100% square and vertical or it may leak even with a crush washer. I put grease on the tap to trap the shavings and run diesel fuel through it before I go back to the spec oil.......

It might cost you 50$ to do it right but that left case is rare and going up in cost as fast as gasoline.

[ceaserthethird]

DC it's the Right Case, and YES the Correct way to fix is with a TIME SER.

I saw Last night at the NAPA autoparts store they had a Kit like this for $30-$40 bucks.

Keep us Posted, I've have used.

[k00leo]

I have good and bad news...


the bad news is that five stores/shops that i went to do not re-tap/helicoil stripped/damaged threads...

The good news; i went to TrueValue and bought every type of screw that i think would fit, and i actually found one.

If i recall correctly, it is either a 9/16-12 or 9/16-18. Not too sure.

Anyway, i screwed it in the drain hole, and low and behold, it works. I put a special washer on it, put a little bit of lock tight on the threads, and hopefully, problem fixed.

Im letting the lock tight set all night before i put some oil in.

You have no idea how happy i am. Hopefully, problem solved. If not, I will be back here for more advice.


Thanks a bunch dirtcrasher and ceaser.

[bannedbrraap]

If you HAD no other choice you could allways find an aluminum plug and weld it in, then re- drill and tap

[bigbadktm]

my buddy has the exact same problem with his 86 R, let us know if that works for you

[200XMichigan]

You'll wanna be carefully with the one size large bolt method rather than a timesert or heli-coil. My buddy was riding his bike that way and we were on the freeway doing about 80, well it was Albuquerque, so doesn't rain much. I thought it was pretty weird it started raining out of now where and then the back end of his bike started fish tailing everywhere, then I realized it wasn't raining, his rickety drain plug popped out and started draining his oil and slinging it all over his back tire and on me. Fortunately he was only on a 450 Suzuki, and was able to not crash. But the bigger bolt will work for a while but it won't be permenant. Plus its a 2 stroke, no oil pressure light to go on. You might not notice till it was too late. Fix it right and fix it once.