My bike, 2018 Bobber with 11k miles has developed a rear/driveline harmonic vibration that occurs from 50-60 mph and can be felt in the seat. The vibration comes on and off like a heart beat from 50-60 mph and in 4th gear.
The odd thing is that the problem developed just as I put a new tire on the rear. Tying to rule out a balance issue, I have had the tire balanced 3 times. The last time the tire was broken down and rotated on the wheel. I still donít like the fact that this tire is taking far more weight to balance than any previous tire. Part of me still wants to believe that the coincidence of the vibration and the timing of getting a new tire points to the fact that I may have a bad tire.
The odd part about the vibration is that it is only in 4th and only in the 50-60 mph range. It is quite noticeable. It is present both on and off of the throttle but seems to disappear when the clutch is engaged. All bolts are tight, swingarm has no play, chain is in spec, and wheel is perfectly aligned. I am wondering if it is possible that a bad tire is being felt at this speed/rpm because the harmonic vibrations coincide with what the engine is doing in this gear/speed. I am tempted to purchase another new tire to rule this out. Worse case scenario there is that I have a another tire for the next time that I need one.
I am afraid that if the wheel/tire is not the issue, I may have a problem in the tranny with 4th gear. That would not be good.
Has anyone heard of any tranny/4th gear problems with this generation of motor? I wish one of you guys was close to me. I would try and talk you out of your rear wheel for 15 minutes so I could rule out where this is coming from.