I was in Nepal from 24th Dec 2001 to 7th Jan 2002, admitadly on a truck, but I can give you some info.
I did meet an Englishman, Richard, on a Honda Dominator in Kathmandu (he's in Australia now having shipped hiself and his bike there), and he said that his only problem was that the bike had started making some "odd noises", possibly due to the altitude.
As to road blocks and the like yes there are road blocks and don't expect to ride during the night. An example for you, we left Chitwan (you MUST visit the Chitwan park, but don't expect to see any tigers) at 09:00, heading for Katmandu. The road is good (as most of them are in Nepal), two lane tarmac. We were first stopped in a 4 km queue (god I wished I was on a bike then, I can tell you) because of a landslip. Once past that we were stopped in two more 1km queues because of military checks (foriegners, especially westerners have no problems with the police or military). We eventually arrived at the outskirts of Kathmandu at 21:00 (in the dark), to be presented with yet another queue of traffic (mainly buses and trucks). This was caused by military carrying guns checking EVERYBODY. Again, foriegners (Tourists) had no problems (just smile and speaks English), but locals do have a hrd time (I saw one Japanese guy having some problems (they were'nt going to let im in) until he convinced the soldiers that he wasn't Nepalese.
We drove our truck past the queue of traffic and talked our way through the check point (remember, the Nepalese are desparate for tourist dollars) and into Kathmandu. Of course by this time the curfew was on and nowhere was open.
I talked to some other people who did the same trip two days before and it tooke them 6 hours. Kuck of the draw.
If you do get to Kathmandu, Sams Bar (in Thamel) is a good place for a

or three and the Holy Lodge (100 metres away) is okay for cheap rooms, but does have three steps before getting into their courtyard, which is a bit of a fiddle for your bike, but it is a safe place to keep the bike.
The big thing to remember about Nepal, is that yes they've got some terrorist problems at the moment, but this is NOT directed at tourists. And that that word - TOURIST - is your magic "get out of the sh1t" word.
have fun
Tony Pattison