I have 2 xt660 one is 100% standard and has NO running problems at all, not a mod on it. Rides smooth no surging at all. And I have one with all the mods. If you don’t want to add all the mods just make sure the tick over is set to 1.5 and just set your 02 between 10 to 15. Make sure you have no free play at the throttle grip And maybe add a k&n or dna air filter. That would be my advice if you do not want to add the kev fuel mod or go down the pc route .One thing I will say the one I have with all the mods dose pick its feet up when asked and it’s a lot more responsive. But there is nothing wrong with the ride of my standard one at all. And is still a joy to ride. All though I let the wife ride that one lol.