How the hell do I get this bolt of the cylinder head?

[Jayy]

Hi Guys,

I'm trying to remove the cylinder head on my Aprilia RS 125 and I've managed to get 3 of the bolts loose but one just isn't moving. I have not rounded the bolt off trying too much to get it loose with an allen key.

What's the best way to remove this?

https://i39.tinypic.com/25722di.jpg

Bottom left bolt

Thanks in advance,

Jay

[tutton]

Allen key socket to get enough leverage?
mind just took a quick crack, and was fine, perhaps lube her up with penetrating?
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Past: '05 Peugeot XPS '99 Aprillia RS125 '94 FZR600R
Current: '02 ZX636 A1P '51 CCM R30

[Kickstart]

Hi

Some large pliers might well do it. You can remove the barrel without first removing the cyinder head cover or the cylinder head, which would give you the space to use some pliers (those bolts are not that tight).

If that fails they get a set of torx bits and use one slightly too large and tap it into the allen key bolt. It is a bit of a bodge and you will likely damage the torx bit but can work.

All the bst

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Jayy]

Thanks for the speedy replies guys... I have put some oil on it to loosen it and it's not moving.

The other 3 came off really easily but this one just seems impossible to move. I have since put a screw driver on the end an tried to chisel the bolt to move but nothing...

[tutton]

with the ones i couldnt get out, i used pump pliers, very gingerly and slowly mind, or molegrips, will fook the bolt so get some more on order but youll have the jacket off.
____________________
Past: '05 Peugeot XPS '99 Aprillia RS125 '94 FZR600R
Current: '02 ZX636 A1P '51 CCM R30

[tshort2007]

i find that cracking it sharply is best. Use an allen key, hammer it in gently so its nice and snug in the socket head, then give it a sharp, but gentle tap. Keep tapping harder to the point where you think its about to round the head off, it should crack by this point. If not, try cutting the head of the bolt carefully with a hacksaw so you can fit a flat blade screwdriver in, OR file the sides down so you can fit a spanner on. I wouldnt try these last two unless you have some good mechanical skills, as you may end up making a bad situation worse.

Patience is the key here mate!

[----]

I had a similar problem on a dtr125 rear brake disk.
Being alloy i didn't want to heat it with the blow torch so i poured boiling water over (kettle full) it slowly to heat it up,then got the mole grips on it.
Might sound stupid but it definately made the difference on mine

Good luck.
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DRZ-400sm

[DaveH]

[_sketch_]

Could try an impact driver? did the job for me not too long ago. - and handy tool to have
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A sucker for 2 strokes
Cagiva Supermoto project

[1016]

as above, plus - if you have no luck with a decent pair of mole grips (preferably 'soft jaw' type, quite hard to find now) locked on really hard, then you can get some to free off by tapping medium hard on top of allen bolt - obviously you don't really go for it, but enough to shock both threaded components. Looks like hex is still good though so, (as has been said) slightly oversize or good quality/good fitting allen 'socket' bit. (if you have some old larger key you can carefully custom grind it to be a slight interference fit).

[Blue_SV650S]

Another vote for long nose mole grips. Unless you have a hand like a vice, I don't think you will get enough 'grab' with a set of pliers.

I've got many a stubborn bolt out of this nature with a set of these:-

https://www.machinemart.co.uk/shop/product/details/pro102-61-2in-long-nose-locking-pliers/path/pliers-snips-cutters


Where they are thin nose, you can really get some 'bite' on allen bolt heads over some fat-boy mole grips that tend to twist on the head where they are too big!
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The purpose of life is to fight maturity.

[Jayy]

Will try the gripped plyers idea then, seems like the next easiest one to use.

What's a torx grip?

[Kickstart]

[tutton]

O my god i was right for once,
thats what is also known as pump pliers, worked a treat on mine...
____________________
Past: '05 Peugeot XPS '99 Aprillia RS125 '94 FZR600R
Current: '02 ZX636 A1P '51 CCM R30

[Blue_SV650S]

[Pete.]

First thing I'd do is give it a good sharp crack on the side of the head using a small hammer. This will break the bond between the bolt and the alloy.
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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

[the grim reaper]

If you're using a standard allen key then get one you don't mind breaking and put a hollow lever over the end to improve your leverage. If you're using a ratchet type then get a breaker bar on it. If the bolt rounds then go for the torx (note spelling!) option above and get on the breaker bar again.

Cheers

Grim
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Adverts don't always work: Remember that advert, where the army are running across the desert and they have a wounded man on a stretcher. They get to a ravine, the bridge is down and a caption pops up that says, 'What are you thinking?'. I don't know about you but I was thinking, 'Christ, I'm glad I'm not in the f***ing army'.

[Jayy]

This bolt seems to be locked in place an not moving at all.

I've had the grip plyers on it where you lock the distance an lock them on as tight as possible an it won't move.

I've been chiseling like f**k with a hammer and chisel at an angle an it won't move.

I'm stumped. There's no room to get a saw in there as it's still in the frame. I don't have the knowledge to remove it from the frame. Think I'm going to have to leave it till Friday.

[Kickstart]

Hi

Presume you are taking the barrel off to check the rings. In which case the head being in place makes no difference.

My guess would be that someone has cross threaded that bolt last time it was apart.

All the best

Keith
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[Jayy]

Well, I'm not a mechanic but I have a good idea that the piston has snagged on the barrel or the head needs replacing.

Since I've owned this bike from May 08 to now, I've had 3 cylinder heads in it. Twice were engineering faults and were replaced and this is the 3rd one.

I have also had the piston replaced Dec 08.

Reason I'm taking it apart is because my mechanic is on holiday until Friday and I thought I would have a go as I have never done it before.

I was riding it down the street few week ago and got it up from 1st gear to just below the redline and something just went "POP" and I lost all compression, the bike was still running but I had to keep it in really high revs as it was drowning out. I managed to get it back to my house which was half a mile away and it cut out.

Every time I tried to start it, it was firing out the exhaust. So I presume it's just the piston/barrel as there seemed to be loads of compression in the bike when I did the thumb test on the spark plug hole.

Plan is, fix it and sell it before it dies on me again, I'm god damn fed up of that bike now. I want a ninja 636.

[Kickstart]

Hi

The barrel is held on with 4 nuts at the bottom and a bolt on the metal bracket across the frame.

Remove the exhaust, drain the coolant (drain bolt on the side of the engine at the front, labelled aqua I think), unbolt the airbox and unclamp the carb from the carb rubber, slide the carn and airbox back. Remove the battery and battery tray, unbolt and remove the power valve. Boltbolt the bracing piece across the frame from the frame and from the barrel. Unbolt the 4 nuts holding the barrel on. Carefully lift the barrel up, and as it comes up put a piece of cloth under the piston (so if the rings have snapped, as the barrel comes over the rings a lump doesn't drop into the engine).

That bolt you cannot undo should not be that tight at all. If it is taking even a fraction of the effort you say it is then there is something wrong there.

All the best

Keith
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[Ariel Badger]

Put a knock out punch over the head and give it a hard smack with a hammer. The shock very often eases things up.
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[tshort2007]

This is what i would do now:-

Drill it out. Get a drill bit slightly larger than the diameter of the shank(threaded bit) of the bolt, and drill carefully down onto the bolt. You WILL ruin the bolt, but as soon as you have drilled past the head of the bolt, the bolt head will free off, leaving just a stud, and the engine head should just lift off (might need tapping gently all round with a rubber mallet, or block of wood and a hammer to break the gasket). you should end up with about 6-8mm of thread sticking out the block. With the block out the way, you should easily find that the pliers refered to above will fit round and remove the remaining stud!

Keep us informed mate!

[tshort2007]

[Kickstart]

Hi

That bolt just holds on a thin cover, not the actual head. Effectively it is just the outer water jacket over the head. The gasket is a rubber O ring. If you remove the head you will be left with barely anything to hold onto, and if it is already that stiff I suspect someone has cross threaded it or use a very strong grade of loctite.

Drilling it out would be my last resort, and give that you can easily remove the barrel without touching the cylinder head cover and the bolt is vertical, if I did want to drill it out I would take the removed barrel to a small engineering shop to secure it properly and use a piller drill.

All the best

Keith
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