04-18-2015, 01:56 PM
(04-18-2015, 10:07 AM)Griso Guy_imp Wrote: My 2014 DLX is supremely smooth at just about any rpm. That said I believe it may be a perception issue. What is smooth to me may feel like a ride on a 441 BSA Victor to a mortal man.
I have been riding 45+ years. Many of those years were on large displacement British parallel twins. The absolute definition of vibrators. So maybe I have a high tolerance for annoying vibration. Anyway my other bike is a Moto Guzzi Griso, 1200cc's of twisting force. At idle it shakes like a paint mixer at Home Depot, as the revs build it smooth's out beautifully. Anyway vibration like the OP described is strange, especially the part about "I've run it up and pulled in the clutch; and it all goes away." So it only vibrates under load?
I'm in this boat. Rode big parallel twins for many years. Parts falling off because of vibration induced metal fatigue was not unusual. More than once I had my throttle wrist go completely numb on a long trip. That said, the vibes from any inline 4 seem relatively minor. Ultimately, I think it depends on what you're accustomed to.
Inline 4s have excellent primary balance, but will always have a secondary imbalance due to the two sets of pistons reversing direction simultaneously. It's more of a high frequency buzz that increases as rpms rise. Some people are more sensitive to this higher frequency than others.
My CB11 has the most buzz in the region of 4K rpm. I think it actually smooths out a bit at 5k (because of the balancer?), since several times I've found myself going down the highway in 4th gear at 5K, having not bothered to shift into 5th. I got some Grab-On slip on foam grip covers last year and it did help a bit with the buzz at highway speed.