Suzuki GS 450e from 1981.
The left spark plug becomes sooted after driving a while.
When changing to a new spark plug it can ride for some time before it becomes sooted again.
When it is sooted, the spark plug does not spark correctly and the motorcycle has limited torque, since it only rides on one cylinder.
Any ideas on what can be wrong?
Sometimes it is possible to 'remove' the limited torque by riding for a while, there is a small explosion and there is no limited torque anymore.