I ported my own originally when I got my scoot used. After a while, a leak developed at the rear cylinder head and I couldn't stop it. It resulted in terrible vibrations that would shake my eyeballs out and SVS
I bought a Nemesis
(which I really liked) and recently the seal at the rear cylinder head started leaking.
I recently bought a new stock manifold and ported it myself (I burned out my Dremel in the process
) and installed it with oversized O rings which leaked at the rear cylinder head.
After consulting with Clifford and Curt, I got stock O rings and Yamabond adhesive gasket material. I coated around the O rings and installed the stock/ported manifold about three days ago.
I am currently waiting for my new throttle and clutch cables, so I won't know if I have resolved the issue.
One of the problems I have had was finding a caulk/adhesive gasket material that is impervious to gas. Hope this is it 'cause I want to ride real bad!!