Just pulled it out of a 99 400 scrambler, and it looks like it says 012, so the other way would be 210, except the 2 is upside down.

It has a bog from half to full throttle, so I removed the airfilter and it went screamin like hell. I figured it needed a smaller jet, but if this is a 210, thats already smaller than factory.

Its all stock, BTW....

Plug was a little black but not real bad, also...

What do you all think?

 

What type air filter do you use? Try put there more open air filter or clean your. You are right black plug, it can be too reach mixture. Spark Plugs Overview

I don't know exactly what type carb you have (I have mikuny bst 40), but check the float level and pilot air/fuel screw adjustment.

 

It had a factory filter, and I put on a new one and drilled some tiny holes all around the metal airbox lid. I also dropped the needle a notch, but the little test I did on the plug was sorta grayish, so I raised it back up two notches.

I'm happy with it for now, but may move the needle down to where it was or add a few more holes.

Thanks!