CBR125 downpipe removal

[BumpingUglys]

Hi folks, wonder if I can beg a little advice here?

The downpipe on my CBR125 was cracked so I decided to replace it; came to remove it and it sheared at the cylinder head, leaving about 8mm of cuff protruding and the rest in the head.

I've soaked it in penetrating oil and been at it with molegrips, lightly tapped it with a hammer and chisel but it just ain't moving. Obviously I don't wanna get medieval on an ally head. The engine is still in situ so it's pretty tight quarters, and I don't wanna remove it unless I really have to.

So, current thoughts: Hacksaw some cuts down the visible metal, then try fold it out of the port, and/or warm the bike up (at the bottom of the garden...) and hope the heat loosens the cuff. Or, I could get a pipe wrench and try twist it out, but that probably can't be done without taking the engine out.

Any thoughts/ideas or anything I'm blatantly missing?

Thanks

[Avora]

If mole grips aren't working on it, then filing two flats on the thread and getting a spanner on it might work. Other than that, your fast running out of options. Keep at it though, sharp impacts will make it free. Sometimes its better to use an impact driver to get these off first time. Good luck, I've been in similar positions the past year with my bike.
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[MaybeGuy]

you can drill and tap the snapped stud if you're careful without any drama
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Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[The Tot]

Get a propane blowtorch from any DIY shop and heat the area around the sheared stud. Direct the jet at the metal surrounding the bolt. You then should get some molegrips and go at it again. If it's only one stud, then a good 5-10 minutes with the torch should do the trick. It won't warp the cylinder head.

I had a similar issue when replacing the sump on my Ninja because of a cracked sump bolt boss. When undoing a few of the bolts, the heads sheared off. So I was left with 3 studs. I managed to get 2 out using this method but the other one was siezed on due to the galvanic corrosion between the steel and aluminium alloy.

It's worth giving it a go.

Oh, DON'T douse the bolt with penetrant spray BEFORE you use the blow torch for obvious reasons. I did it anyway just for the jokes! WD40 + engine oil makes a nice flame.
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[BumpingUglys]

Hi guys, thanks for the replies.

I think I didn't make myself clear enough in my original post, sorry.

I have the studs out no prob, it's the actual end of the downpipe that's stuck in the cylinder head. Instead of just being a normal type manifold, the downpipe has a thick steel cuff that slots into the head to a depth of 15mm or so, which has, I guess, heat welded itself to the aluminium, shearing off from the much thinner pipe when I tried to remove it, leaving 8-10 mm protruding out and the rest inside the exhaust port. The ring of steel that's left is about 50mm in diameter and approx 5mm thick and it's this I'm struggling to get out.

[stinkwheel]

Soak with penetrant spray overnight (plusgas, 3 in1 spray penetrant, duck oil or even some ATF thinned with paraffin. NOT WD40).

Apply heat to the area with a blowlamp. Headers on a motorbike can glow red at times so I doubt you'd be able to apply enough heat to damage it with a blowlamp. If a drop of oil vapourises immediately on contact with the metal, it's hot enough.

There is also freeze and release spray. This works well if alternated with heat.

A slide-hammer with an expanding chuck would be the tool for the job but I've never even seen one. I'm pretty sure they exist but I bet they're an expensive tool for the few times you'd use it.
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[CarlosCBR]

I had this EXACT problem when i bought a second hand engine a while back. I put a chisel onto the cuff that was poking out and used a hammer to knock it out. One short sharp whack should have it off bud. If not, try a few.

Just try not to chip the head when you do it, but you will avoid that if you are not resting the chisel on it.
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[SoND]

[Robby]

I would go for hot and cold first rather than brute force, Honda seem to be using some very cheap metal on their 125s these days.

Heat the whole area with a blowtorch, then freeze and release around the inside of the steel cuff. That should crack it off enough to tug it out. Freeze and release is excellent stuff.

Alternatively the old headstock bearing trick, which works surprisingly well on headstock bearings that absolutely won't budge. Run a bead of weld around the inside of the steel part, it cools in seconds and the bit drops out. This has worked on headstock bearings that I've been bashing at for an hour with no luck.

Clean the area up as much as possible first - work a little screwdriver around the steel part to scrape off as much rust as possible from the lip whichever method you use.

If neither of those work, penetrating oil then try to twist it a little with a pipe wrench. Once you've crack off the corroded join it'll fall out.

[stinkwheel]

[BumpingUglys]

OK, now it's the weekend I can afford to make a little noise (in the morning). No welder so I'm gonna blowtorch/freeze it with the hammer on standby.

Thanks for all the excellent suggestions guys

Edit: Heat and a couple of sharpish whacks did the trick. Thanks guys

[cbrtrxtdmvfrD...]

Take 1 x cheap Blowtourch
heat area for 1 minute
A gentle tap
Remove
what to expect below
https://i1244.photobucket.com/albums/gg571/dboon11/1_zps20119060.jpg
https://i1244.photobucket.com/albums/gg571/dboon11/2_zps5ec792a6.jpeg
https://i1244.photobucket.com/albums/gg571/dboon11/3_zps896a7d26.jpeg
Hope this has been of some help [/img]
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Right' O

[Ariel Badger]

WTF
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Bikers make great organ donors, get 115 on your licence today.

[Clutchy]

Yes, I'm sure OP has been sitting at the computer for the last two years waiting for that reply, helpful, but suspicious, I smell spam?
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Malaguti F12 Phantom-Dead, Suzuki AY50- Dead, NRG power DD LQ, CBR125.
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[P.addy]

Regardless of age, the only reason is due to lack of giving a fuck... the state of that engine

[SQL]

holy thread revival

[P.addy]

What a fucking turd burger, didn't scroll down enough

[RockandGrohl]

This is exactly what I did today. Exhaust collar welded onto the block, cheap Honda shite. Took two of us 15 minutes of solid heating, whacking with hammer and chisel + tugging with grips. But it came off cleanly enough.

I stuck a gasket in, popped on my aftermarket exhaust I bought used and.... it's some cheap shite and won't fit.

So I'm exhaustless.

Bingo bango bongo.

[Ariel Badger]

The thread that keeps on giving, I believe the OP died of old age.
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[Vincent]

https://www.youtube.com/watch?v=EBjxf-donE0
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