Stuck bolt. HELP!

[slime bomb]

My friend and I were attempting to do his valve clearances on his 2020 KTM 690 smr. On doing the exhaust you have to undo two 5mm Allan bolts to release the rocker arm to replace the shims.

One Allan bolt came out with a bit of a fight, the torque setting is only 15nm and we had to use a braker bar! The other ones head has sheared.

Tried so far:

Shocking the bolt
Hammering a Torx bit in
Impact driver

Welding something to it is an option but don't want to fry anything.

Does anyone think a bolt extractor is the way forward because we're running out of options?

[merlin75]

bolt extractor will def get that out, where abouts are you

[Xcore]

If the manual impact driver won’t budge it your in serious trouble!

[25th QV]

I second the bolt extractor.

[Turn7]

Extractor may well work, but it’s going to dump a load of swarf into the head….

[dudleybloke]

Small chisel or punch and tap it loose with a hammer.

[Chicken_Satay]

Take a slightly larger torx bit than intended for that head and hammer it in with a manual impact driver. Use the traction from the hammered in bit and the impact driver to ease it free.

Drilling and using an extractor tool will throw metal shavings all over the place.

[SlimJim16v]

A set of these, or the expansion set depending on the size you need. I think you'll need to weld it though.

https://www.amazon.co.uk/Irwin-394001-Fastener-Rem...

[mr shoddy]

can you use a disk cutter in a dremel to cut a slot in it?

[Hustle_]

Impact screwdriver

[Krikkit]

Chicken_Satay said:

Take a slightly larger torx bit than intended for that head and hammer it in with a manual impact driver. Use the traction from the hammered in bit and the impact driver to ease it free.

Drilling and using an extractor tool will throw metal shavings all over the place.

This, spot on

[slime bomb]

Thanks so much for your replies and I'm in Stoke on Trent.

I've tried drilling the head of the bolt with an 8mm drill but it's down to about 9mm and the shoulder is only 5mm and the heads not coming off yet.

I did think about an extractor tool and if I can get the head off and the tension off it I could use a left handed drill bit to get it out. Does that sound right? I've called it a day now and off for a stiff drink!

Once again thank you so much for all your input.

[SlimJim16v]

I was just going to suggest a left hand drill bit. I've never tried it myself though, so don't know how well it works.

[julian64]

tricky place. get a cryo spray from the chemist. Used for getting rid of warts

step 1 small blowtorch (the sort used for creme brulee)
step 2 cryo spray
Repeat step one and two several times

Then try the torx bit. Be aware that you want to turn the bolt back and forth rather than just put all the effort into unwinding.

[Biker9090]

£15 manual impact driver from Halfords


Absolute lifesaver for this kind of stuff. Had similar problems splitting my CZ engine but this did it no bother.

[ouninpohja]

Just go straight for the left handed drill bit, everything else is generally a waste of time

[W12GT]

It’s worth soaking underneath it with plusgas. Do this multiple times over at least 24 hours. Use a hole punch into the head and a light tap with a hammer before and after every plusgas application.

Worth cutting a slot into it with a dremel. Then use a manual impact driver.

Also consider trying to tighten it then undo it - but go easy.

Good luck!

Edited by W12GT on Thursday 28th December 22:47

[bimsb6]

W12GT said:

It’s worth soaking underneath it with plusgas. Do this multiple times over at least 24 hours. Use a hole punch into the head and a light tap with a hammer before and after every plusgas application.

Worth cutting a slot into it with a dremel. Then use a manual impact driver.

Also consider trying to tighten it then undo it - but go easy.

Good luck!

Edited by W12GT on Thursday 28th December 22:47

A dremel with a cutting disc is the worst thing to try , abrasive grit inside the engine will destroy it .

[Steve Bass]

Apply heat to the head and let cool. Repeat this a couple of times. Reason is heat and cooling will break the bonds and any thread lock that may have been used
Then use a left handed bolt extractor. I found they work better with a small pilot hole drilled in the centre of the head recess and then insert the extractor into the deeper hole. The Allen recess is a bit shallow to get a good grip going.
Obviously fill the surrounding area with rags and shop cloth to prevent any swarf from getting into the motor.
For reference I had exactly the same problem with a rear caliper bolt and the left hand extractor had it out in seconds.

[trickywoo]

Steve Bass said:

Apply heat to the head and let cool. Repeat this a couple of times. Reason is heat and cooling will break the bonds and any thread lock that may have been used.

I was thinking about red thread lock. 15Nm sounds like nothing for an unlocked bolt in that location. You won't shift a red locked bolt without heat from a torch. What does the manual say about thread lock for refitting?