case bolt broke, how to fix

I broke the clutch casing bolt below/inside the casing. It’s at the one o’clock position and is a M6-1 bolt about 3” long. It’s a hex bolt with a concave top, blue in color. I tried the extractors and they don’t reach that far into the casing, except with the t-handle and can’t get a grip. I ordered reverse drill bits but they will arrive Tuesday.. (saw at AZ at lunch ). If the reverse drill bits don’t work (scares me to be drilling in there even with a depth gauge) I am to install a heli coil or time-cert (I’ve done time-certs on fords).

The casing hole is 2” deep but the hole with the broken bolt is 1.5” deep. It seems the fix will install the new threads at the outside of the casing, hopefully to the engine. Is there a problem with this, the casing out there is thin, I would rather get the thread deeper and with more threads but it seems these things are very short. :excuseme:

My idea is to get a bolt length that will go thru the casing (3/4”) plus another inch, so say 2” long )M6-1, 2” length). Does this sound like a good Idea? I have been sitting looking and praying each time I work on this problem…..Well any advice is appreciated/needed. :lol:

Maybe I will just install the thread fix and forget about drilling out the broken bolt portion (1/2” lodged in casing).

This is the same size as the oil bolt so maybe I can fix that. :excuseme:

Try going in there with a small flathead jeweller's screwdriver - see if there's an edge you can catch, the last time I had one of those break off, I was able to just turn it out simply by flicking it in the right direction on an edge i could catch

Hi Matt,

I did something like that, at first I tried to match up the broke bolt..

then I tried screwdriver, philips, some of those safety screw drivers..no luck.

Actually when I was drilling I think I drove it deeper (it already torqed it off so its my imagination). My small drill bits were swimming around at first, so I useed a larger drill bit to help center me in the hole, then slowly created a dimple in the middle which i tried to drill out with the smaller bits. I am waiting on the reverse drill bits but I am leaning towards the thread fix and buy a short bolt, will this hold??

I should be able to install a m6 thread but I dont want to drill out my casing at all to accept the insert.

Thanks, I need help before I mess it up More

reverse bits work well - wouldn't surprise me if it pulls it out in seconds. Hopefully you didn't mar the threads so it'll come out smooth.

You probably did push it in further - bolts do not torque because of bottoming out on the end, theres always space there - they torque because of bottoming out on the head.

Another way to try it is to jb weld a small stiff wire or nail ground flat on the tip (just a small dab on the end) and get it in there centered (wrap with paper, push paper in first then nail through paper, leave paper) then let it cure and twist the nail out with the end of the bolt attached. Paper just there to create barrier so JB weld doesn't touch case, only broken bolt.

The long bolts in the position you are talking about pass entirely through the right side crankcase cover and thread into the crankcase itself. Your idea is a poor one, because while the shorter bolt would clamp the clutch cover, it would not properly secure the crankcase cover. Remove the whole crankcase cover, extract the broken bolt, and repair it correctly.

Well, I would like to to it right.. lets see kick starter, radiator hoses, ...

Can I save a couple of steps from the manuel?

Like - dont bother with the muffler?

skip the oil cover and filter removal if possible ?

disconnect radiator hose instead of taking apart water pump cover and inerds ?

Just some stuff that comes to my head... So there are no threads in the outter casing. I can get at all the bolts on the crankcase off- so I am just trying to save some time. I need more time, I got a cam mod and a new rim to lace ohhh and then there are my kids bikes

The header may be in the way, or it may not.

You will want to remove the impeller cover so that you can rotate the impeller as you reassemble the case to the engine in order to engage the drive slot.

The filter cover can stay on, but the upper forward bolt must be removed, as it holds the case cover down to the crankcase.

Another way to try it is to jb weld a small stiff wire or nail ground flat on the tip (just a small dab on the end) and get it in there centered (wrap with paper, push paper in first then nail through paper, leave paper) then let it cure and twist the nail out with the end of the bolt attached. Paper just there to create barrier so JB weld doesn't touch case, only broken bolt.

I know this is an older post but ... thank you! I had one of the small bolts holding the cover on the rear MC of my KX125 break - left a bit of the bolt down in the MC resevoir. I used a small drill bit end with JB Weld and was able to screw it out! Thank you!! This post was invaluable as I didn't have a clue as to how to get it out!:bonk:

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