At the end of last season engine would not return to tickover when put in neutral. Had a closer look recently and clearly running rich with black exhaust smoke and sooted plugs, mixture screw made no difference. Checked thermal enrichment device and needle moves out about half inch with 12v. The leads to this device from the CDI both have <200ohms resistance to ground and when engine is running there is no voltage across them. Tried 12v directly to thermal device and engine runs much better but still some misfiring and again no change in engine speed by turning the mixture adjustment. Compression is just above 130psi lower cylinder and just below 130 upper. The carb had a professional ultrasound clean at Yamaha dealer Spring 2019. Any advice would be much appreciated.
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Ft9.9 ae x 1998
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