Someone have ad this problem , the engine hesitate at 1/4 throttle but only when engine is cold (for the first 2 or 3 minute of ride when engine is cold ) look like fuel delivery problem ,
does the water temp sensor did something with fuel delivery ?

if it was map or iat sensor , he would hesitate when he is hot too ?

What machine? Year and size.

Brute force 750 2012 eps fuel injected

Sounds lean when cold but not so when hot. Might test a few things like that map sensor, the TPC and the idle air valve. Also look for something physical like a cracked TB boot. I would also test the fuel pressure.

Tb boot are good
I dont have thinking about the IAV who can stay open .
Fuel pump mod have been done 2 year ago ,
destruction of screen in fuel pump assembly new strainer and inline filter , but if it was fuel pump the problem will be more at wot throttle , than at 1/4 throttle .
I have put a wideband on the past , to set the afr with a hmf fuel optimizer and this bike run realy rich , but i dont know what is the normal AFR mapping ?

AFR Regular 87 pump gas w/or without 10% ethanol content:
Idle around 12.8 - 13.4 O2
Mid Throttle 12.3 - 12.8 O2
WOT 12.3 - 12.8 O2
I was told plug reading is not real true with today's fuels, but after I installed new piston rings, my plug readings vs. AFR readings are pretty damn on the mark.
When I had worn rings, no oil smoke out exhaust, engine consumed oil, and compression was good, you would think the plugs were always rich and sooty looking, but the AFR readings were spot on.