broken screws

Hey everyone
Today i was removing the battery housing from my 81 kz550 ltd. While removing the screws that hold it to the bike, I somehow managed to break all four of the original screws leaving the bottom halves stuck inside the holes. I tried everything i could think of to remove them but in the end i was forced to drill through them which removed the tread inside the holes. Needless to say it was a miserable experience trying to rig the new screws to stay in place. Does anyone have any tips or tricks to get a broken screw out of a motorcycle for future reference?
Thanks
Nick

I'm not trying to be a smartass, but the best tip is not to break them. If you soak stubborn fasteners with Kroil for a couple days they will come out with very little difficulty. I have used it to loosen fasteners that I thought would be impossible to budge, and they came out without a problem. Ed

650ed has good advice. a type of soaking agent can sometimes go along way. But after the damage is done i would of tried gripping it with some vise grips and heating it gently and try to rock the pliers slowly until it starts turning. But since its drilled out. I dont know how think the metal is there and how big you drilled your hole but you might be able to use heli coils or time serts. Or if the bolt goes all the way thru maybe use a lock nut?

Penetrant. I've never used Kroil but it's supposed to be good, as mentioned. LiquidWrench penetrating lubricant is a good alternative - it's readily available & cheap. Just spray & let it sit overnight or longer - spray again in the morning & let it sit. etc.

Heat. On some stuff, you can use heat from a propane torch, but I would only do that w a part off the bike... such as the fork bottom allen bolts or fork caps. Or wheel dust cover screws. Or tail light bracket bolts.
Never use a torch around the fuel tank, carbs, or wiring.

Vibration. Sometimes you can use a wood block & hammer to tap, tap, tap - use in conjunction w a penetrant. A hand impact wrench is good for some fasteners. Use the proper bit, fit it to the screw head, then whack the end of the tool w a hammer. The stator cover screws & pulsing coil cover screws come to mind. A lot of guys end up replacing those because the screw heads get buggered... mine still look almost new.

Thanks everyone. I ended up using a nut to connect another screw to keep the two pieces together. It seems to be working fine. Next time I'll use some spray first

also if the bolt goes all the way tho wirebrush the thread to remove most of the rust helps as well ...

Kroil your friend

cant you tap a new larger thread
should have drill it what ever the bolt size was