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.
(https://i.imgur.com/OUUmNSe.jpg?1)(https://i.imgur.com/SDirCoM.jpg?1)
(https://i.imgur.com/KyGAcay.jpg?1)(https://i.imgur.com/JhvHp7d.jpg?1)
(https://i.imgur.com/Y8pXvWj.jpg?1)
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. (https://uploads.tapatalk-cdn.com/20190508/eaa9a0cadffc92d33a84c75d6c6fde6a.jpg)(https://uploads.tapatalk-cdn.com/20190508/578cd92af0aba7c9c32da55341b37bd3.jpg)(https://uploads.tapatalk-cdn.com/20190508/f38312f33a9f708e507fe1a9a283b95d.jpg)(https://uploads.tapatalk-cdn.com/20190508/4463730a32a309752a88a98ca077e75b.jpg)
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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.
They look incomplete to me, knock the bridge between the holes out & they would be more like what I would expect
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.
(https://i.imgur.com/b7x6xFE.jpg?1)(https://i.imgur.com/dHmBNku.jpg?1)(https://i.imgur.com/bpNYX9r.jpg?1)(https://i.imgur.com/Wy9QFEx.jpg?1)