Rounded master cylinder bolt

[Mudskipper]

I've done a search and read this thread

One of mine chewed up yesterday, thing is it's a countersunk allen socket head (2.5mm) rather than cross head.

I tried hammering a 3mm allen into it, but it just made an even chewier mess

Which is my best course of action? Drill into it, or the centre punch method? Or impact driver - with flat head?

Am I right in thinking that the centre punch method means using it like a kind of drift, to force the head to turn?

I've priced up a new m/c cap at 25 quid so would rather not fuck it up. Plus I'm rather keen to be able to bleed my bastard brakes

Suggestions appreciated
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CBR125|||GSXR400|||CBR400|||CBR400|||CB250RS|||GSXR750|||CB250RS
"You're clumsy, you eat too much and you behave like a 12 year old boy. But you know what? Every once in a while, you find a thumb."

[joop200789]

can you get a pair of molegrips onit,worked for me in past,

[Mudskipper]

[Odie]

Try a small "tork" bit (looks like an allen ket but has more sides).
Tap it into the mess you have left that was once your countersunk cap and gently turn it.
Has worked for me before
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[stirlinggaz]

hi,
on one of the chinese bikes i owned, the bolt on the m/c was made out of some cheap alloy & rounded off as soon as i went near it with a hex bit.
& being countersunk, i couldnt cut a slot in it or even get a grip of it with anything.
so i just used the dremel, fitted a small pointy(ish) grinding stone attachment & ground the head off. then just lifted off the m/c cover, leaving the exposed stub.
i removed the stub with a screwdriver after cutting a slot in it.
obviously replaced the bolts with decent ones.
cheers,
GAZ

[Kickstart]

Hi

First trick is to try taking it out with a torx bit (star shaped).

You can try undoing it by using a punch to try and turn it. Can work. Depends how tight it is.

Lastly you can try drilling the head off, then undoing the stump with a pair of pliers / mole grips.

I would do it in this order, as that way you keep all the options open as long as possible.

All the best

Keith
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[Mudskipper]

Cheers everyone

I'll pick up some torx bits and a punch tomorrow and hold my dremel in reserve for now
____________________
CBR125|||GSXR400|||CBR400|||CBR400|||CB250RS|||GSXR750|||CB250RS
"You're clumsy, you eat too much and you behave like a 12 year old boy. But you know what? Every once in a while, you find a thumb."

[stinkwheel]

I have no patience with them at all these days.

If I'm going to be taking the cap off a master cylinder that I didn't put on. I buy two new screws before I start.

I then attempt to remove the screws. If they burr, I just drill the heads off immediately and remove the stub with pliers.

As a matter of fact, I didn't even try unscrewing the last ones I did, I could see someone had already extracted them with a punch THEN PUT THEM BACK IN AGAIN! I figured than anyone who would do such a thing would certainly not have applied copper grease to the threads so I just went straight in with the drill.
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