Weirdness since the re-tune.
It only happens when I fill up. I climb a hill, about 3/4 of a mile long, about 5-6% grade on the way home. If the gas tank is full, to the top, about halfway up the hill the bike starts to stumble, doesn't run right at all. The speed limit up the hill is 60mph.
If I give it more fuel, it still stumbles, but runs a little better. This stumbling will last about 15 seconds of so, about the middle of the climb.
I am loafing along in 5th gear.
After about 15 sec, it starts to run, and respond, and everything is all right. When it starts to stumble., I will tighten down the fuel cap a couple of clicks, not sure if that really does anything.QUOTE)
I haven't run into this with the bikes, but plenty in cars. My R3T (was) equipped with the mandatory calif emissions which included the evap system. Considering the year of yours, I'm sure it has the evap system also. I removed the canister and now allow all those horrid evaporative emissions to exit like they did on vehicles since whenever. BTW I only did this to make room for my horns which are mounted under the LH side cover in the spot previously occupied by the canister.
If you fill your bike as you say, it is possible with expansion that you are overtaxing the charcoal canister, and when the computer system says "purge" it is overfueling the bike. This makes sense, because you stated that it ran better when you accelerated, requiring more fuel, which in turn would make the "overfuel" situation slightly better and smooth it out a bit.
Do you continue to fill the tank after the pump kicks off the first time? If so try this simple remedy.....stick the pump nozzle at least 2" into the fill opening and as soon as the pump kicks off, stop filling. This allows a bit more room for expansion without allowing liquid fuel into the charcoal canister. Hope this helps, let us know.