The stock NGK plug has a custom part number and is only available from the dealer at a premium price. The more common BPR7EIX plug appears to have identical specs and is available all over the web for around $8. I'm running it and it works great.
There are a lot of people, including me, that have had problems with water ingress around the bezel on the speedo display. I found out the hard way when I flooded mine while washing with a garden hose and had to replace it. Nowadays I just slip a plastic baggie and rubber band over it before washing.
You'll be surprised at the detritus that finds it's way into the airbox during the course of a ride or two. I find it's easiest to just rinse it out, which requires temporarily removing the air filter, removing the rubber drain plug, and installing one of those orange airbox intake plugs sold on Beta's parts site (or at the dealer.)
You may also experience problems with kill switch or other electrical function due to electrical connectors coming partly undone behind the headlight. A little dielectric grease and a zip tie helps with this.
You'll probably also get some spooge dripping from the rubber connector between the exhaust pipe and the silencer. Zip ties worked great for me. I've read where some other riders have used stainless steel hose clamps.
I bought a P3 carbon skid plate that works great, but I have to remove it to change to oil. Due to design this also means I have to remove the exhaust pipe too. SOme other skid plates may not have this limitation. I opted to remove the stock plastic skid plate after reading of riders who discovered dented frames beneath them after bashing into things.
I live at 3000' and ride between 2500' and 10,000'. I started noticing performance issues due to running overly rich at about 6000' to 7000'. For me the challenge was the elevation range variation that required constant tinkering with jetting. I recently gave up on that and switched to an aftermarket Lectron carb that handles the changes better.
I'm an Amsoil fanboy and have never run Motul in my Beta, but you may find this comparison interesting. If true it appears that Motul 710 is probably better suited to the typical riding characteristics of the Xtrainer.
http://www.bansheehq.com/forums/index.p ... idnt-know/