I would be really surprised if there're weren't lots of two stroke specialists in Tokyo. You don't have to go to a main dealer for the work.

But as Andy says, the engines are quite easy to work on really. All you need is a spanner set in 8/10/12/14/17 to get started, and a few screw-drivers.

At least take the heads off and take some pictures for us to see, as we may be able to tell you what looks wrong.
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