fuel mixture screws?

I cant seem to find the fuel mixture screws on my maxim 400. The only "adjustment" screw that I can find is for idle speed. I think my bike is running a tad lean and would like to adjust it a little more richer.

 

They are probably still "capped" which is how they came from the factory.

If that's the case, you'll need to do more than adjust them; it means they've never been out which means the carbs haven't been cleaned properly.

Here's an exploded Mikuni; the pilot screw "assembly" screw, washer, spring and tiny o-ring has a red circle around it: http://xjbikes.com/Forums/viewtopic/t=31061.html

You'll need to carefully drill into the caps without going too deep and hitting the screws, and then pop them out.

You'll need to get your valve clearances in spec before you'll be able to effectively adjust the freshly-serviced carbs.

 

Those carbs look slightly different that what's on my bike. Do the 550's use a different carb than the 400's?

 

Disregard that last post I was being stupid and not looking at the carbs in the same view. Looks like they have been drilled already in my bike (PO said he did have them cleaned a little while ago).

 

The carbs on the 400s and 550s are different, yes; but I believe the 400s use Mikunis too.