Welcome; we are glad you joined us.
I doubt the bike you mentioned has a seat height of 28.7 inches.
However, I do encourage you to post in the threads mentioned by Culcune. I'm sure the owners can tell you the actual seat height.
Perhaps you could buy a Chinese motorcycle for yourself, and a Yamaha TW200 for your girlfriend?
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Spud
"Never argue with an idiot. He will drag you down to his level, and beat you with experience."
Mark Twain
2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
2005 Honda XR650L
2004 Honda CRF250X
1998 Kawasaki KDX220
Mods made to my Zongshen ZS200GY-2:
http://www.chinariders.net/showthread.php?t=6894