two things make these run bad
1 ,the carb is set up so weak to pass the emissions for the eu it make them runs badly
2,the valve clearances tighten up on them
take the main jet out and takeit up ten either with a jet drill of just order a bigger one i.e if it has a 60 main jet then fit a new 70 one.
adjust the vavle clearances using a 8or 9mm spanner on the locknut and turn the square drive on the tappet adjuster screw with a small pair of pliers or a special too,i use a special tool same as hondas.
set the inlet valve to 0.05 and the exhaust to 0.08
adam bike doctor
November 2009