20 replies to this topic

[coopersmate]

Hello
I recently brought a Stage 4 head for my 998 and was a little confused by how similar it was to my standard head.
My question is what sorts of visable differences whould you expect to see on the head? I knowe that 1275 heads become very kidney shaped rather than heart and wondered if this should be the same with 998's?

Thanks

Lloyd

Stage 4 head



Standard Head

Edited by coopersmate, 24 February 2008 - 11:32 AM.

[Tomf]

the valves should be alot bigger with a stage 4 head and the ports should be a different shape, put some pics up, next to a standard head and we can help more.

[wolfys_mini]

from those two photos, i can see that the valves are a different size, well they look it anyway, and the chamber is a different shape/size.

what exactly were you expecting? you want to be looking into the ports aswell as the valves and combustion chamber

[coopersmate]

I am not sure what I was expecting. But if you were to give the 2 heads to a lay person they would be hard pressed to find differences. I would have thought a Stage 4 head would have been considerably modified. Take a look at the minisport heads
mini sport cylinder head st4

They are very different to a standard head. Chamfered edges, less heart shape ect.

I am wondering if there is a mistake with my head and do I have a refurbished standard one or something along those lines.

[Ethel]

I wouldn't describe that as a gas flowed head. You would expect to see the metal around the valves cut back much more - the walls of the shrouding look vertical, like the standard head, if the valves are any bigger that would reduce gas flow.
Obvious modifications would be tapered valve guides and multi angle valve seats.

[wolfys_mini]

who did the head?

[Jammy]

Doesn't look like a Stage 4 head at all! The chambers don't look like they've been worked, the valves don't look much (if any) bigger than standard sizes. Does it look like there has been any porting work done?

Just looks like a nice clean head to me.

Wheres it from? Ebay jobbie?

[coopersmate]

The description I had before buying the head was

998cc ST4 L/Free cylinder head by Morspeed

[Jammy]

So you bought it from Morspeed?

This is a St3 998 head pic taken from Morspeeds website:


I'm surprised if that has come directly from Morspeed as they haven't even fitted new valves!

Morspeeds website says your head should have double valve springs and the valves should measure: 33.0 inlet and 27.5mm exhaust.

[coopersmate]

Some pictures of the ports
Sorry they are bad buts its hard to take these pics

[wolfys_mini]

unless it was sold as not new but not used loads.

Edited by wolfys_mini, 24 February 2008 - 01:21 PM.

[coopersmate]

Just measured the sizes of the bottoms of the valves. I assume this is where the measurment is taken from.

[Ethel]

Push a valve open, if it's unleaded you will be able to see the valve seat as a ring of darker metal that's been pressed in - slightly larger than the valve seat. If it doesn't have that it's obviously misrepresented.

[coopersmate]

Push a valve open, if it's unleaded you will be able to see the valve seat as a ring of darker metal that's been pressed in - slightly larger than the valve seat. If it doesn't have that it's obviously misrepresented.

Any suggestions on how to do that without a spring compresser. It does have double springs by the way

[Ethel]

Place the head upside down on a flat surface with something under one of the valve stems and push.