Took my standard 3 door cossy for its first MOT for a good few years today, and its basically running really rich. I can clean the black sooty plugs and it will be fine for a while and then soot up again and start misfiring.
I got the MOT tester to stick it on the machine and it was registering 9.9 somethings at idle, whereas it should be around 3.
I'm hoping it is something simple as the car is not taxed or tested so I cant take it anywhere to get it sorted. The car has only done 2000 miles in the last 14 years so the problem could be related to the lack of use.
Thanks

 

Have u tried adjusting the mixture with the mixture screw on the engine ecu.Put the car on an emissions tester n turn the screw till the emissions get back 2 where they sud be.

 

I wouldn't do that IF you know that the car was running well enough previously to pass an MOT before the car was laid up and nothing has been changed since.

Sounds like it could be either the water temp sensor at the rear passenger side of the head, or the wiring to it.