Impact driver for carb screws - Overkill?

[FlightRisk]

I hate little hex socket head bolts. (The ones you need an allen key for.)
One is stuck solid and has started rounding off and now I'm wondering if an impact driver is what I need for this sort of thing.
No job too small that it doesn't require a new tool purchase.

Oiled it and left it overnight but no joy and now allen keys (small 2.5mm) won't get a firm grip on it.

Hitting small carb bits with a hammer hitting type tool seems a bit drastic but then I'd really quite like to hit it with a hammer right now. Lump hammer or sledge ideally...
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Honda CB500S

[G]

I'd go for a mole grip on the outside of the screw if you can.

Oh and absolutely most definitely do not put it back in!

[FlightRisk]

There's nothing to grip unfortunately, it's a rounded head one and it's in an awkward spot so no chance of filing a slot in it.
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Honda CB500S

[G]

Got a picture?

I'd be trying getting an appropriate sized trx head wedged in there (light tapping with a hammer).

I'd consider some heat on the outside of the carb (being VERY aware of what a carb typically contains - use extreme caution!)

[Fizzer Thou]

Drill off the socket head and remove the carb part.Then use molegrips on the bit of the screw that is now exposed if it does not come out using just a pair of pliers
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Just talk bikes.What else is there?

Always have a 'Plan B'

[Bezzer]

Try using a centre punch lightly tapping it around the hex hole to tighten it up first, if you end up properly rounding it off then go for drilling but with left hand bits, the hex head ensures you are in the centre and the left hand drill often just unwinds it straight out. You can get a set of 10 for a fiver plus the postage from Tracy tools, they're imperial sizes but that doesn't matter.
https://www.tracytools.com/10-left-hand-drills-hs-various-sizes-from-1-16-tlo-3-8
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I used to be indecisive but now I'm not quite so sure.

[Raffles]

It sounds as though you're dealing with a 4mm screw.
Before drilling the head off the screw, you should send a 3mm drill straight down the middle of the fastening to a depth that is just below the underside of the screw head. If, after removing the screw head, you are unable to grip the remaining threaded section of the fastening then you will have a pilot hole available to drill out the remnants.
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A good loser will always be a loser.

[WD Forte]

Some folk have used coarse grinding paste in the holes
of philips and hex heads to remove worn screws
Might work, might not
Ditto JBkwik
Also, a suitably selected torx bit may get enough of a grip to remove it.
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bikers smell of wee

[c_dug]

I wouldn't want to go hitting a carb too hard, too much risk of breaking it.

I'd go with G's suggestion of the torx key first, if you have one. If not I'd skip straight to fizzer thou's suggestion of drilling the head straight off. Personally I wouldn't faff around with left handed drill bits, nor holes down the middle. Once the pressure is off the bolt the remaining threaded part should unscrew easily, I doubt it will be corroded in or anything.
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I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock.

[stinkwheel]

I've drilled the head off carb screws many times and the stub has always come out with a pair of pliers.

I wouldn't be hammering anything around the flange of a carb, they are very easily broken.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[STONEY!]

Meh, I strip and rebuild carbs on a daily basis and 7/10 times I use an impact driver to undo the screws. I used to use grips and still sometimes do but I have found the impact driver to be the best option most times.

Tap the bit into the screw first, then give the driver a few light hits and jobs a good un. Obviously the emphasis is on light hots if you go at it with a sledge hammer then yes you will probably break something.

[Islander]

I've used a small, sharp cold chisel to tap the head round on stuck screws with a good degree of success. Carb bodies aren't made of glass and as long as you take reasonable care you should be ok.

[jjdugen]

If its the last one, just tap the float bowl backwards and forwards, this usually loosens its grip enough to get it out with grips.
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The CBR900RR has been sold. Aprilia Falco worms its way into my heart.
Try Soi 23 on Amazon for a good read.... Self promotion? Moi?

[FlightRisk]

It defeated the Torx method, I realised there was actually just enough space to cut a slot in it with a piece of hacksaw blade. Didn't work either.
Don't have any chisels or punches but I tried tapping it around using an old screwdriver as a punch. Didn't work.
It's not even the float bowl, it's a little M4 bolt holding a pipe right in the way of the last float bowl screw.

As was pointed out to me above it did occur to me yesterday that maybe bashing cast aluminium parts with a big hitting stick was not the way of happiness.

Thanks for the tips. I'll just do what Fizzer Thou said and drill the head off - should actually leave a decent amount exposed to get a grip on, which I didn't realise at first. Found replacement bolts on Wemoto.
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Honda CB500S

[FlightRisk]

Oh but I came across this little impact driver, not sure if this would be any good for this kind of lighter stuff in future?
Of course I didn't see any impact hex bits that small, I presume normal ones would just sheer off. Are impact drivers even any good for hex?

https://www.machinemart.co.uk/shop/product/details/laser-7535-38-drive-micro-impact-driver-set
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Honda CB500S

[lihp]

I'm guessing somebody put stainless steel socket heads into an aluminium carb?
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covent.gardens: lihp is my most favourite member ever

[bassmastergen...]

[stinkwheel]

[lihp]

[FlightRisk]

[Fizzer Thou]