The upshot of this is that there will be many GP800 owners faced with something they have not had to consider for a long time - if at all, the adjustment of the final drive chain.
The rear axle has a 28mm nut on one side and the other side has a hex soxcket to take an allen key to lock it to prevent it rotating when undoing the nut. Unfortunately, this socket is 22mm so you are unlikely to have a big enough allen key to do the job. Fortunatley, HPS come to the rescue with a simple socket adaptor. Until I bought the adaptor, I could only hold the axle with a box spanner - although it did the job it did not provide a particularly good fit in the socket. http://www.bikehps.com/acatalog/BikeHPS_OnlineStore_Workshop_Tools_97.html came to the rescue with an adaptor. I also took the opportunity to buy a new 28mm scoket and a 22mm socket for use with the adaptor. http://www.tooled-up.com/ supplied these very swiftly and efficiently at a good price.
According to the book, you check and adjust the chain with the bike on the centrestand. You first remove the chainguard and you are looking for a chain deflection of 38mm (+/- 2mm) to a specified point on the swinging arm.
This does seem to fly in the face of conventional wisdom but I guess the guys at Piaggio must know what they're doing as it seems about right - I have to say that I think they're slightly on the slack side but their calculations seem to allow for the take up of the suspension quite well.
Incidentally, if anyone's wondering about chain life, it slackened phenomenally in the first 2,000 miles and has barely needed more than a tweak since. That was always the hope (that the transmission would not make it a chain killer) but it's nice to be confirmed. I'm now at 4,500 miles and have no chain issues.
