YZ250 Porting

[Nkreig]

I picked up a 1982 YZ250 cylinder on Ebay and the seller did not know much about the porting done to it.  Could someone with a trained eye tell me what I am looking at?  I know the 4 small ports added to the sides of the intake are called Boyesen ports but, in all the digging I have done, I have not come across any done like these. 

[Banshee Hp]

I replied in your other thread but the porting looks pretty clean over all. The boyesen or boost ports are awfully small. It's really a touchy area on most cylinders and if you dont do alot of them, breaking through to a stud hole or the outside of a cylinder can happen quick. The durations of the other ports have more to do with the overall performance of the cylinder than boyesen ports. Here's some pics of some cylinders I did lately.

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[Nkreig]

The ports you did look like what I have been seeing.  I think Ill open them up a bit more as you suggested.  I'll have to measure everything when I get the old cylinder off to compare the two.  Ill post my findings.  Nice work btw.

[tony27]

They look incomplete to me, knock the bridge between the holes out & they would be more like what I would expect

[Nkreig]

I finally got around to opening up the boost ports today.  This is my first time doing any port work, I tried to do as much research as possible before I dove in.