Bore spacing of the K100/K1100
Turbo Mini Forums

Does anyone know the bore spacing of the K100/K1100 engine?

Or could someone measure a head for me?

Just want to check something out.

Much appreciated.

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."

Well, my K100 head was here when I got back from my holiday.

The bore spacing is 76mm for future reference.

Attached is a .pdf file of the following bore spacings:

K100
998
1275
1215 (BYB Pg376)
998 +0.080 Offset 0.035"

If anyone would like an autocard file of the above please PM me.

Attachments:

20.16kb

Edited by Paul S on 27th Oct, 2007.

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."

axel, I'd love a pdf file on the above, please can you emal to me? Pint for you at the next meet,

Jim at sheepspeed dot com

Team www.sheepspeed.com Racing

Jim,

I've sent you an Autocad .dwg file. I hope that's what you want.

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."

I put the head on a standard 998 A+ block yesterday.

This is a photo of cylinder no. 2:



As you can see, the cylinders do not sit on the same centreline if you use the existing three centre front head studs. The centreline is out by approx. 2.5mm.

The No. 2 cylinder shown is the worst.

However, +0.120" pistons and approx. 1mm offset bore towards the exhaust sorts it out.

I've revised the CAD file. Let me know if you would like a copy.

Edited by Paul S on 28th Dec, 2007.

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."

looks like a winner then! very interesting project, will the bore offset effect how it runs? iv read in fundermetals of motor vehicle book that having it offset can reduce postin slap but i think the pistons are different aswell

David.

The offset will be +0.035 east/west to even up the bore spacings and +0.040 towards the exhaust to expose the valve.

I'm not sure that it will have a significant effect on how the engine runs. With the short throw of the 850 crank, rod angles are at a minimum.

It would probably be better to move the bore towards the inlet, then it would have lower rod angles through the combustion stroke.

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."

Hi Paul,

could you send me the AutoCAD drawing you have of the bore spacings. It would be very helpful to me.

Thanks.

Ewan

PM me your email adress.

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."

Does anyone know the original bore spacing of a 1275 block?
I could have one probed, but thought I'd ask first.