[LordVardamir]

As I mentioned in another thread, I have been trying to identify why my new-to-me EX250 is running like crap. It runs with somewhat bouncy idle at half choke and dies with too much throttle or the choke is released. Spark plugs showed me it is running lean (white tips). So... what gives?

Took the carb out again and compared it to another I had laying around. The main jet emulsion tubes sit way lower on my carb (right in picture) than the spare carb (left in picture).
I swapped the main jet emulsion tubes from the different carbs back and forth. The carb on the right always has the emulsion tube sitting lower than the other one.

My running theory is that the lower emulsion tubes and jets means wayyy less fuel is getting picked up by the main jet because it sits higher above the fuel when installed on the bike. But does this really have an affect at idle? Is there any reason to have the main jet sit so low?

More food for thought: The carb with the low main jets had the idle screws set to around 4.5 turns out. Has anyone seen this before?

I may be having a chat with ducatiman about cleaning my spare carb up....

Thanks for reading!