I wasn’t quite sure of you description of the problem.
Does it occur at certain speeds no matter which of like three gears you are in?
Or is it related to engine revs regardless of speed? If it’s related to engine revs does it do it more in some gears than others but it’s still engine revs related?
Obviously the former it’s going to be related to tire balance, tire or wheel run out, disk brake runout on one of the disk brakes, or even belt condition, tension or belt harmonic damper. Even the belt alignment can cause similar issues.
Now, I’ve had two Spyder’s from new. A 2021 RT LTD and now a 2026 Sea to Sky.
My experience is that the 1330 cc triple is much like my prior Triumph Trophy 1215 TTSE triple. They are a little bit raw. Especially as they go up to just below peak torque at around 5,000 RPM. These are not sewing machine smooth engines. For their capacity they are a longer stroke than Yamaha triples, being roughly square in bore to stroke for more torque.
Hence, until they run in a bit they can feel a little harsh or vibey. Do they pass vibrations through the grips, mine do. I have to loosen my grip and just use a loose grip so as not getting to the point where my hands tingle at freeway speeds. Although they are a 120 degree crank I don’t think they are extremely well secondarily balanced engine. They do have a kind of pulse firing sequence at the revs they most frequently operate in. If they were a true motorcycle engine, They would probably be tuned to make 160 bhp and rev to 10,000 rpm and cruise at a much higher rev limit and hence appear smoother. They remind me of my Triumph 1215 cc engine and less like the smooth power of the Triumph 765 cc engine.
Like I said mine smoothed out with miles but they still had a raw edge to them. Now yours may be bad enough it’s worth investigating further, only you would know the answer to that, but in my experience they are not the most refined three cylinder engine I’ve had.