Stuck oil drain bolt

I searched and didn't find this on the forum, so here goes.

This KZ900 I picked up has a rounded off oil drain bolt. Luckily the oil filter bolt is good and I was able to drain the oil and change the filter. Still, I'd like to take out that oil drain bolt and replace it.

I used a can of "freeze off" and tapped the bolt with a hammer, then tried unscrewing it with a vise grip. No luck.

My next thought is to grind the sides of the bolt so that there are two flat surfaces to grip it and unscrew it.

Either that or drop the entire drain pan and drill the bolt out.

Recommendations?

Had the same issue before so I used a file to square up the sides until a socket fit. It was a pain but wotrh the effort on the next oil change.

Kapahulu wrote: ...KZ900...rounded off oil drain bolt...used a can of "freeze off" and tapped the bolt with a hammer, then tried unscrewing it with a vise grip. No luck.
My next thought is to grind the sides of the bolt so that there are two flat surfaces to grip it and unscrew it.
Either that or drop the entire drain pan and drill the bolt out.
Recommendations?

A "rounded bolt remover" tool is available from Sears or Harbor Freight.

Meanwhile, would try heat with a torch -- instead of the "freeze off" -- because the aluminum pan should expand more than the steel bolt when heated, and thereby relax its grip on the bolt.
And thinking the pan would contract more tightly around the bolt when cooled.

Good Fortune!

Pull your fuel tank off and carefully lay the bike on its side to get better access. Removing the oil pan is NOT that big of a job if all else fails but you will likely need a new pan gasket. Good Luck!

I had the same problem just two weeks ago. Mine is a 17mm hex and rounded. I have an old imperial ring spanner set and I carefully filed all six flats down to the next size 5/8inch (15.875mm). I left the sides on the large side until I was able to tap the ring spanner on with a hammer for a good fit. Make sure the whole width of the spanner is engaged, so the new flats are not rounding off as well. I also think a bit heat would help.

If you cannot get it out any other way you may want to drop the pan and take it to someone with a welder. They can weld a steel bar to the bolt (it's steel) and then unscrew it. You won't need to drill it. Ed

taildragger1197 wrote: Pull your fuel tank off and carefully lay the bike on its side to get better access....

Yes, and would also remove the battery.

Old tires, pillows, mattress, or soft grassy lawn.

Good Fortune!

Welded on bolt/T-handle no doubt....
OR
Since most home owners own a RED handled pipe wrench....
Heat and a pipe wrench for truly locking down/gripping on that rounded head.... Yes, it will be toast afterwards but sounds as though it already is anyways....

Luckily I have a spare motor in the back yard. I dropped the pan on the old motor, cleaned it up and swapped with the pan on the bike.

Pretty messy, there's lots of oil in that pan that doesn't come out when you drain the oil via the oil filter. It was a good chance to clean out all the gunk. I don't know how many years/miles ago it was since the last owner did that and there was some nasty stuff in the pan.

Another interesting thing - the spare motor sat in someone's back yard for about 30 years. I bought it along with a bunch of other rusted parts off a KZ1000. The outside of the motor looks like crud. The inside is nice and clean!