Advice on how to remove broken bolt

[IINoxiousII]

Hey guys,
I'm new to this so forgive me if I am off on my terminology. I ordered a centrifugal clutch recently. Everything was going great. I had it installed and it was working perfect. I noticed at high RPMs that there was slipping, I think, with the clutch pads, so I disassembled the clutch, tightened the clutch and as I was re-assembling the centrifugal gear I broke off the main bolt that holds the centrifugal gear into place into the crankshaft..... I took off the centrifugal gear and the bolt is broken flush with the crankshaft. I can't get it out and I don't think I will be able to bore it out. Hopefully I'm wrong.
I was wondering what can I do? Your help and advice is greatly appreciated.

I attached a pic of what I'm working with here.
Thanks guys!
Kind regards

[Al.Fisherman]

If that bolt was supplied with the clutch kit, it shouldn't be too much of a problem. The hardware supplied is c**p just soft junk...that the good side. You will need to take a center punch, and punch the end of the broken bolt as center as you can. Then start out with a small drill bit 1/16" and drill as far as you can go. (I'll measure for you how deep the hole is and report). Then step up to a larger drill bit. Keep going until the hole is ALMOST to the threads. Then remove the broken bolt with a easy out/screw extractor. When replacing the bolt use a metric grade 8.8. It NEVER amazes me the amount of riders that depend on the junk hardware supplied with these kits.....

Update
The hole in the crankshaft is 1/2" deep. When replacing the bolt, do not get one that will bottom out in the crankshaft. Thinking about it I'd see if a stud and then a locking nut, to hold the clutch on will work. If so, I think that would be a better set up. Keep the drill as straight as you can when drilling. Picture of stud and nut. Of course the stud has to be cut to length, and the threads are 8 X 1.0

[IINoxiousII]

Wow, thanks Al!
A lot more than I was hoping for. Definitely a newbie move on my part over torquing the cruddy hardware I was provided. I definitely will up grade all shoddy pieces that will be under more stress than they can hold. Your prompt reply is diligent and greatly appreciated!
I hope my application is as good as your explanation. I will keep you updated.
KR,
P

[Al.Fisherman]

Wow, thanks Al!
A lot more than I was hoping for. Definitely a newbie move on my part over torquing the cruddy hardware I was provided. I definitely will up grade all shoddy pieces that will be under more stress than they can hold. Your prompt reply is diligent and greatly appreciated!
I hope my application is as good as your explanation. I will keep you updated.
KR,
P

Here are some tips on installing a HT engine.

[Fabian]

If you are installing a centrifugal clutch, there is a necessary modification for long term reliability.

Send me a PM and i'll send you the web link.

[Fabian]

From past experience, a broken clutch bolt is usually caused by the bolt bottoming out at the end of the crankshaft recess.
I had to grind away the last three threads from the bolt to enable correct clamping pressure.
An easy test: cover the last 10mm of the bolt with paint; let it dry and install the centrifugal clutch.
Remove the bolt and see if any paint has been removed from the end of the bolt or the last few bolt threads.

[steveonbroadway]

I take out broken studs all day at work, "auto machine shop" you really only have to get the tip of easy out say about 4 mm or so.. hammer it in your drilled hole.. dont break off easy out in it... you have to FEEL it...

[IINoxiousII]

Thanks guys,
I feel like this is a title bout for the main event tomorrow. (That's when I have time to work on it lol). Good thing I have you all in my corner! All I need is the theme song from Rocky. Will keep you guys posted

[steveonbroadway]

If you like I can send link to drill bits I use they are made by Irwin double sides 1/8 and very Sharp.

[Al.Fisherman]

There are at times a "left handed" drill bit will work.