The centre is usually a good colour, but it is only the very centre, electrode, ect. The ‘outer ring’ is always black and wet. No matter how it’s ridden. I removed the bottle top plug I have on the carb to filter rubber, to let more air in and the engine ran a lot better. Not proper but better...
The Mikuni website begs to differ "Kit may be installed easily on TM and VM series Motorcycle and Snowmobile carburetors."
The carbs that Yamaha use are not the same. They are made by Mikuni but they are made to order. The power jet has no ‘brass screw in’ adjustability. It’s just a casting. There are a few other differences like having heater pipes and lack of air~jet brass screw adjustability...
@DtxPower Best jetting for Athena 170 is 300 main jet on the
standard Mikuni tm28 carb but with the powerjet blocked off. Just cut the rubber tube in half from the float chamber to the powerjet then block the 2 halves of the rubber tube with a couple of 5mm threaded bolts or similar.
As for cleaning it, I admit I usually leave my carb alone as much as possible and leave it for those more experienced then I however cleaning it isn’t too hard.
If you can take the carb off yourself then locate someone with an ultrasonic cleaner and Chuck them a tenner, failing that go to your local bike shop.
However there are plenty of extremely detailed and fool proof tutorials on YouTube for the DT125R look this, courtesy of my favourite grumpy old git of a DT enthusiast, Frankie. link text