Topic: Broken Bolt

[grandelatte]

This is my second day of owning a CB750K1.  It needs lots of TLC.  One of the issue I discovered is a broken bolt on the points cover.  If it were sticking out a bit, I would use a pair of pliers to turn it, BUT it is broken even to the surface.  Do you have any suggestion to how I should get it out?     

TIA - Jim

[Patrick]

Go to Harbor Freight (or some other hardware store) and get left handed drill bits. If you are lucky the bit will grab the broken bolt as you drill into it and spin it out.

Patrick

[myhondas]

Center punch it.....drill it about 1/8-3/16" deep and use an easy-out to remove it after spraying it with a good penetrating oil like PB Blaster.

[Terry in Australia]

Whatever you do be careful mate, that is a pretty soft casting around the remains of that screw, so don't just go wanging into it with a hammer and punch.

If you can file the end of it smooth you'll have a much better shot at punching it dead centre, and that's really important, because if the "left hand drill" method doesn't work, you may have to drill the screw out completely and use a helicoil to replace the thread, and if you're off by half a mm (or don't drill parallel to the old screw's angle) you'll just end up with a mess.

You might get lucky with an "easy out", I've found that the square ones are really good as they seem to "bite" better than the fluted type, but just make sure that your drill bit is nice and sharp so it doesn't "wander", and use plenty of penetrating fluid. Cheers, Terry.  

[gane]

Jim, As most of us have found, broken bolts/studs are common, and depending on location can be real bears. Offer this. Your' 1st approch is often the most critical.  With nothing to grab, you'll need to drill...It's important (and I can't over ephasize) that 1st drilling is EXACTLY centered.if neccesary file/grind whatever, old bolt/stud until it's possible to center punch a center before drilling. then,,, penetrating oil, next, actual drilling.start w/smallest reasonable drill possible (preferibly Left handed) sometimes this will work in itself, if not, attempt light heat (prophane til spit sizzles) and ez-outs. this needs be done before hole in offending bit is so large that ez-out simply swells bit and increases seizure. still no luck? drill progressivly larger hole until remaining bit can be prized/cracked/broken out piecemeal. even if this has damaged internal threads, it still provides a good basis for drilling/installing a helicoil or better yet timesert. Sometimes welding extensions to bit is possible, and heat/leverage allow removal. Ulta sonics is another option in some cases. Your' problem is pretty straight forward as these things go, hope there's something here that helps, luck G

[MCRider]

Everything that has been said is good to try. Luckily its just the cover screw and you could get by without it worse come to worst.

My 2 cents, file it FLAT. Center punch it, get a REALLY SHARP drill bit, brand new cobalt tip or whatever. Smaller than the OD of the screw which is 6mm.  Drill it down the center. USe favorite tool EZ Out or such to remove it.

The reverse drills sound intriguing, I've never seen or used one.

If it gets really messed up, you can use a 1/4-20 American screw rather than a helicoil. Get the old crap out, tap it to 1/4-20, which is just a skosh larger than 6mm and get a screw to fit.

Restoring it to 6mm is always preferred.

[Don R]

If you have access to a small mig or other welder you can hold a washer over the bolt and weld the washer through the hole to the bolt. let it cool a little and turn the washer with channel locks, If it breaks off try again. Sometimes it takes more than 1 try. I have also used a thin nut. not for the faint of heart but I've had good luck with it.

[grandelatte]

thank you all.  i will try your suggestions tonight.   

[Yoshi823]

If you have access to a small mig or other welder you can hold a washer over the bolt and weld the washer through the hole to the bolt. let it cool a little and turn the washer with channel locks, If it breaks off try again. Sometimes it takes more than 1 try. I have also used a thin nut. not for the faint of heart but I've had good luck with it.

I think that the heat from the welding may well soften the corrosion between the ally crankcase and the steel stud,so making it easier to get the remains out.

Good idea to helicoil the hole as well.

[grandelatte]

thanks guys for your help.  i found Black and Decker screw extractor at Home Depot.  i followed the instruction and it came out in one piece.



again, thank you so much for your suggestions and encouragements.