Master cylinder screws rounded off

[_Troy_]

Afternoon all.

I was hoping to bleed my brakes today, but have fallen at the first hurdle. Both screws in my master cylinder are very soft, and were very rounded off before I even gave them a try. Now they are just awful. I've tried adding a touch of WD40, but it hasn't helped.

So any ideas on how to remove them. I've researched some good ways, but being very small and extremely soft, I'm not sure many of these would work.

As a last resort I'll simply take it to my local garage and get them to remove the fuckers, but I'd like to give it a go first.
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650

[P.addy]

Hammer and proper screwdriver.

Failing that, replace them...but get them out using a flat head screwdriver and hammer to knock the screws round.

[stinkwheel]

Either tap them round with a small punch and hammer or drill the heads off and unscrew the stump with a pair of pliers.

I generally land up drilling them off. Use a 6mm drill and go slowly, dead easy to drill because they effectively self-centre into the rounded off crosshead.

Very common to get this problem due to a combination of them being a water-trap and due to them usually being a true crosshead screw, not a posidrive or JIS. Most people have posidrive screwdrivers and if you use them to undo a crosshead, you stand a very good chance of burring them.

Replace them with a stainless socket head capscrew. M4 countersunk is what you want.
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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.

[carvell]

I got mine out no problem with an impact driver *just* as they were starting to round. You're probably out of luck now, but remember that for next time!
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Yamaha TDM 850

[DrDonnyBrago]

Drill off the head, the cover will lift off and reveal some of the shaft for you to get mole grips on. Screw is likely an M4 countersunk.

Replace it with a st/st version. I bought some posidrive M4 countersunk st/st screws for about 10p each at a nut and bolt place in WSM.

[Pete.]

I've had good luck removing those by using a small ball pein hammer to worry the heads flat until you see the cross begin to close up, then hammer a No2 phillips screwdriver into the cross. The shock of the hammering helps to release the thread and the countersink taper and tapping in the screwdriver makes a perfect fit. You only get the one chance usually though.

You can use this to tidy up the tops of screws when replacing the reservoir cap too.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Dave-the-rave]

Or batter a flat headed screw driver in it. The biggest head that fits and with a long shaft/handle. Push down hard when turning. If that fails get into the recess you have just made at an angle and use the screw driver as a punch. Knock it with a hammer anti clockwise at an angle until it's loose.

[_Troy_]

Thanks for all the help guys, I'll give them all a go.

To be honest the screws were buggered before I even got to them, and were as soft as cheese. Needed replacing regardless, but was hoping to get them off at least!
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650

[Dave-the-rave]

You'll get them off mate. The above methods all work. Just have a think about what method to try in relation to how your screws look. Only you can see them. Most if not all are made of cheese but they're cheap to replace.

[_Troy_]

Like a boss.

https://farm9.staticflickr.com/8213/8342778258_accb71108e_c.jpg

https://farm9.staticflickr.com/8212/8342778314_1b21d0daa5_c.jpg
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650

[Dave-the-rave]

Nice. Your new screws don't need to go in over tight.
If the diaphragm is good it will seal nicely without
torquing the screws enough to damage the heads.
Push down hard on the screw driver. I like to give it
a tap with a hammer just to seat it in the screw head
properly, thus preventing damage to the new screw.

[_Troy_]

[stinkwheel]

[_Troy_]

[P.addy]

See... the bodge fixes do work well.

[_Troy_]

[djr]

[P.addy]

Awesome seat

[_Troy_]

The tape is mostly on the back/bottom and by my leg. Doesn't look too bad, but helps to keep me dry. I'll put another on if I ever come across a bargain.
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Current bike: ZX6R J1
Previous bikes: CLR 125 | GS500 | ZX6R G2 | SV650