Fireblade engine decoke

[dern]

I've just taken the head off my 929 in order to rethread a spark plug hole and the head, pistons and bore tops have some carbonisation as can be seen here...





Do I need to bother removing it? If so what with? Can I do this without removing the valves?

Also, what's the best tool to remove the gasket bits from the head and block?

Thanks,

Mark

[Pigeon]

dern said:

Do I need to bother removing it?

Might as well, now you've got it apart...

dern said:

If so what with?

Piece of brass, brass wire brush...

dern said:

Can I do this without removing the valves?

Ideally you'd remove the valves, but given the amount there is in the pics it probably won't make much difference. Are the camshaft mounting arrangements such that you can put the cams in and use them to hold open the valves on the pot you're working on?

dern said:

Also, what's the best tool to remove the gasket bits from the head and block?

A broken stone (whetstone, one of those square blocks that you use for sharpening chisels etc.) Flat side to the face of the head, let the broken edge scrape off the gasket goo. Plenty of diesel or paraffin splashed about as a lubricant.

[MeLLoN Stu]

i'd take the thick of it off, but don't worry about getting it all shiney and new

a brass wire brush will do nicely, but try to avoid the mating faces despite how soft the brush is, i find masking them off works fine, just be sure to clean them with paraffin to remove any remaining adhesives. before you nail it back together a squirt of carbon cleaner might be useful, available from RS components i believe.

as for taking the gasket off, soak it in parffin and you'll find a plastic spatula does the trick, saves risking any abrasion or scratching too. if that doesn't work RS components sell pretty effective gasket remover, been tamed down a bit in recent years to remove the "instant death if breathed in" factor which is a shame as it used to smell lovely, but its still quite effective.

[Matthew C]

Apparently you should pack some grease round the edges of the pistons to prevent the bits of carbon getting down the sides where it can score the bores, then carefully wipe the grease away to which the carbon should have stuck.

[Trooper2]

I wouldn't recommend using anything other than plastic scrapers to remove old gasket material from Aluminum heads or blocks, even the finest of scratches can lead to leaks later on.



Edit: or an approved solvent.

Edited by Trooper2 on Sunday 18th June 13:33