I have no idea to be honest.

 

I install 142.5 main & 40 pilot for the 351
I install 140 main & 37.5 pilot for the 331

 

I grabbed a KDX snorkel for $5 off of ebay so I will put that on first and replicate Bills set up before I do anything else.

Bill, what is your 250/300cc jetting?

 

Bill's carbs come jetted for air lid on. I recall a former member named Marty who said he had a BillBlue Tm-34 running well with lid off, but he was using close to a 140 main...137.5, as I recall. I actually think he could have gone richer. I'm currently running a flatside, 34mm pumper with 142.5 main, NO airbox..it's a K&N style filter clamped directily to the carb. Don't try this off road folks