FS1 forum

Here's some pics of a 43mm cast iron cylinder I did a while ago

You did the exhaust in a not so normal but genius way

I did some cylinders with this construction... only the exhaust... there you have to built a specially made one... because the flow in the pipe is different

a homoet or something wont run nice on this cylinder

that will rev quite high I guess

Strangely enough this cylinder will be quite low revs as it is, probably 11k with the right pipe. Durations are quite low with a low blowdown figure so will make good torque. I ran this shape exhaust port on the Notso Special and it was nice to ride with a really good power spread but really came alive when it hit the powerband.There is scope to increase the exhaust duration by another 10 or more degrees but the rider is heavy and we want it to pull well, so will try it and see and maybe lift the port more later.


We may try it with a Homoet pipe and see, should be ok with such a low exhaust port.

Great porting
May I ask what your durations are?

No problem, very low exhaust duration on this to leave room for more development. Ex 180 Trans 130 boost 128 with single base gasket fitted.

Flika schreef:No problem, very low exhaust duration on this to leave room for more development. Ex 180 Trans 130 boost 128 with single base gasket fitted.

Oke thanks, the exhaust duration is low indeed, but, like you said, you can make it higher for development.
but how width is the exaust port? You can make it very width in the shape you have make it, can't you?

From memory I think the widest part of exhaust port was 40mm, haven't got the cylinder to measure as it was for someone else.

Flika schreef:From memory I think the widest part of exhaust port was 40mm, haven't got the cylinder to measure as it was for someone else.

Oke, that is a very wide port.
Thanks for your information!