fitting a k100 8v head to a 998
Turbo Mini Forums

i am a little confused, i have seen this kit on ebay for only a small fee, what i am after knowing is will this head bolt straight onto a std 998 as the guy selling this kit says it will, my mate says it wont and i swear i have seen on here that wolfie or someone 'plonked' (as they put it) it onto a std 1275, so can i fit this head with no block mods? god im sooo confused

I'm currently doing a K100 head on a 998.



Miniboo is also and there may be others.

EDIT: a bit more in this thread:



Basically you have to go a big overbore to get it to fit and cut the pistons to clear the valves.

Edited by Paul S on 2nd Nov, 2009.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

to fit a k100 8v head onto my 998 block i had to do the following:

*bore to +80

*inner to cylinders were offset bored by 45 thou inwards

*valve reliefs cut out of the cylinder wall to clear the exhaust valve

* the above meant the the top ring of the pistons would go into that cutout SO we had to lower the pistons: did this by offset bushing the little end with copper bushings by 60 thou.

I also dry decked the head and block and had a water outlet welded onto the block but this interfered with the breather outlet on the transfer housing so i had to use an old 850 transfer housing that doesn't have a breather.

*cutout in all pistons for the valves to clear

Now there are many ways to skin a cat and i now have the engine together and turning over and making good oil pressure, can't check compression yet as i don't have the adapter for my gauge to fit the M/C head.

Unless you have a specific reason to go small bore DONT. it is way to much work(read: money and time) when a 1275 is much easier to do.

I did a small bore because big bore blocks are hard to get here in America, however hindsight says that it would have been cheaper to ship one from the UK!!

I've shifted the head forwards towards the alternator by 1.5mm and bored to +0.120". The bores are also offset 0.010/15" to maximise the meat between the bores.

That way, the work required is less. But when the block needs a rebore, it will be scrap as larger pistons are not available. Maybe Imp pistons could be used, but not Mini pistons.

I've not put it together yet so there may be other problems.

Edited by Paul S on 2nd Nov, 2009.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."