[Dupo]

As far as i know, if its not gummed up too bad you can use something like SeaFoam in the tank to clean it up. If its very gummed up then things just wont move and flow like they are supposed to. That stuff is like molasses when it gets bad. Thats when its going to need to be broken down and done manually or professionally. I would imagine he should be alright with some SeaFoam additive and fresh gas. Also as far as i know, fresh fuel will not break that stuff down.

I do recommend SeaFoam though. Most every forum i belong to says to use it if your bike has been sitting. Stuff is awesome on cars too.