The decision to modify the carburetor should be based on how it works in all areas.
If you have full control of idle fuel from rich to lean then the idle system is up to par.
Test at light part throttle, heavy part throttle, and full throttle. If there is an issue in any area it will need to be addressed to make improvements.
For secondary transition the big players are the cam/spring and choke pull-off release time. The link up the secondaries also needs to be adjusted to make sure it isn't out of adjustment and allowing the flaps to open too far when you go quickly to full throttle and create a momentary lean condition (stumble/hesitation/bog or even backfire up thru the carb).
I see folks over-winding the spring or not installing a new spring in attempts to correct a choke pull-off or link too loose up the secondaries issue.
I'd add here that a big part of getting the secondaries working correctly is to install a new cam/spring as the old cams get worn down and loose on the shaft and the springs get tired and will never adjust correctly. That is why we include them in our complete rebuild kits.
The accl pump is another big player in secondary tuning. It must provide a strong shot of fuel to help cover any lean condition as the flaps start to open. I see LOTS of accl pump issues from folks using cheap parts. NONE of the "blue" seals currently being sold in over the counter and on-line kits are worth two squirts of duck poop. I just had a customer bring down his Marine carburetors last Saturday right after being rebuilt and the brand new accl pumps blue seal had already failed and the carb was only used for one day! I'd also add that the pump they sold him was NOT a Marine pump as it was WAY too long and his kit did not contain the correct high-flow needle/seat assembly.
These are other problems I'm seeing with over the counter and aftermarket parts. The accl pump seals are junk and the spring on the pumps are to long with too many coils so they "stack" when compressed (very bad).
Anyhow, I'd work on correctly your secondary issues if everything else is working correctly and make sure to install one of my rebuild kits to get the carb up to par for this new fuel and get the correct parts in it.
I'd add here that I sell "timed" choke pull-offs for that carburetor part number to improve secondary transition..........Cliff
