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

Hi Flika
Very nice pictures.

The shape of the exhaust port were known as “donkeys ear shape”
I haven’t tried it yet. But it’s supposed to give a good high end rev performance trust keeping a reasonable low rev performance.
It seem a little tricky to machine

I ran this shape exhaust port on the Notso Special and it gives a really good spread of power but comes alive when it comes onto pipe. Durations are set really low right now but we will increase the exhaust if necessary the transfers are at maximum width for a 43mm. It's actually easy enough to cut this shape port but you do need to start with a cylinder with a very low exhaust port height. The opened up dual action boost port was time consuming

Oh yes i haven’t noticed t that the first time.

Looks really great.

And yes this operation will indeed require a cylinder with low exhaust port. Maybe an old 40mm cylinder bored to 43 or 45 mm will be a good start…

Do it have any drawbacks to remove the small support between the aft scavenge ports

As long as the port is no wider than 22mm works fine no ring problems at all, at 50% bore width the rings don't open into it.

Thanks
I will indeed try that approach.
Looks very promising.