7 port head details
Turbo Mini Forums

Now that Minisport's 7 porter has been around for a while and I'm sure a few people out there have got them, can anyone tell me if it's an exact reproduction of the AKM spec or have Minisport 'fiddled' with the cores? I've seen one or two posts that suggest there might be some differences, does anyone know for sure?

Stuart Gurr worked on my minisport one, he said the were diferences to an AKM one he have previously worked on.

he didn't go into details, but mentioned being thinner around the exhaust seats, and generally a rougher casting.

everything i have heard about the AKM points to them having 45mm intakes (to suit a 45 dcoe) mine is a shade over 39mm at the carb face.

Also minisport have cast their tapezoidal exhaust ports into the head, Stuart ripped these out to a decent size...

here is what they were like as cast.

Edited by Joe C on 24th Oct, 2006.

Fantastic, thanks for the pics. As you say those exhaust ports look pretty small, time to give Stuart a ring for a chat I think and add a 7 port onto my christmas shopping list!

another thing worth noting is Stuart was wary of going past 24cc chambers, so you'll need deep pistions to get the cr down.

also, spark plug length is an issue, idealy my head needs 1" reach plugs.... but try finding them!! everyone else is using 3/4" reach plugs meaning either they have the chambers cut back about 5mm near the plug ( the pics on minisports site don't look likethey have to me) or the plugs have been recessed futher into the head, i don't yet know the chances of finding fresh air if the plug seats are recessed further.

There is a third posibility that everyones running their plugs half way up the plug hole, but i doubt that!

Why not use a K1100 head? Lot better value IMO. Jimster has some photos of the cores laid out for casting of the AKM 7 port. I would have thought that they could have made the deck a bit thicker. It would be quite easy to put a spacer between the drag and cope.

Bugger off, I'm getting there.

a lot cheaper, but a lot more fooking about, fine if your up to the job of sorting all the manifolds/block ect.

with the 7 port the exhaust is all the same as a 5 port.

I called into MiniSport this morning for a look at their head up close as they had a demo on a stand. They use NGK PMR8A (19mm reach) platinum plugs, I tried screwing one into the head and as you say it didn't protrude out of the spark plug hole and into the chamber.
Recessing the plugs further into the head might work but it could also be an expensive way of finding out that the casting is not very thick in that area!!
I'll do some searching around on plugs and if I find anything I'll post it here.

Edited by neilj1678 on 8th Dec, 2006.