I’m currently in Kashgar, in the process of riding through Xinjiang to Pakistan.
If bringing a motorbike or car into China, you’re required to be escorted at all times while on the road by a vehicle of an authorised Chinese travel agency. They must be there to meet you at your point of entry into China and will escort you to your point of exit. This is definitely the case with Xinjiang and Tibet provinces, though I understand it is also the case for the rest of China.
In order for the agent to arrange all the paperwork (various permits) you really need to get in contact with a travel agent in the region you wish to visit 3 months ahead of your planned arrival (2 minimum, though this is cutting it fine). You will need to email copies of passport, vehicle registration etc, along with paying a deposit electronically.
There are a handful of agents to choose from in Kashgar. The details of two tried-and-tested agents are below, both of whom previously worked for the well known, though now-no-longer, Caravan Café
travel agency. You’ll see their names mentioned on various threads over the past few years.
1. Wayne (also known as July Xie), www.xinjiangtibetexpeditions.com
2. Taher, www.newlandtravel.net
A popular route for bikers is from Kyrgyzstan to Pakistan – the route I’m taking. For the benefit of all, it involves the following:
Once you have exited Kyrgyzstan and ridden the c12km of no-man’s-land over the Torug Art pass (note – unlike cyclists and backpackers, motorcyclists can ride this independently), you cannot proceed beyond the Chinese border post until your escort from Kashgar has arrived. This means you will meet them around noon local time. You then follow them the c110km to the Chinese customs post. Passing through is a relative delight (other than being disinfected), since your agent runs around and does everything for you. Then it’s another 60km or so to Kashgar. There you can have a day or two rest, before a day’s ride to Tashkurgan. This is the Chinese exit post. Here you stay the night. The following morning your agent makes sure you get through customs smoothly and then you’re on your own for c220km until the Pakistan checkpost at Sost. Here, I'm informed, you can still get a Pakistani tourist visa on entry (2 passport photos and $90 for UK citizens).
Note: On entering Kyrgyzstan from Tajikistan at the Kyzyl Art pass I was not given a customs declaration form for my motorbike, though the vehicle details were entered into a register. I asked for one, but was told it was not necessary. This I found hard to believe, though judging by other threads and motorcyclists I met it appears to be standard practice. And on leaving Kyrgyzstan, lo and behold, he was quite right. Rather unusually the brief customs declaration form is completed on exit. Nice fellas the Kyrgyz customs.