problems with scooter after head replacement

[delta9]

I just replaced the head yesterday due to broken exhaust stud. I replaced the exhaust with a performance exhaust from ebay. Also rejetted from 108(stock) to 120. Now it kinda bogs when I rev it and when I go WOT and hold it, it acts like I'm going open/closed/open/closed. In the video I go immediate WOT and hold it until I stop video.

Any ideas?

Here is youtube video.

[Shadowfire]

Did you re-adjust the air/fuel mixture screw yet?

[Maddog]

The jetting change was Far too large. Go back to the 108 and try it. If drastic improvement then go up in size. I would imagine a max of 115 but it's really trial and error. Check the plug to achieve the best jet for your conditions.