A sidenote to this discussion is the effect of the flow orifices on the column heights. I use the four column mercury balancer with flow orifices in each hose. Each column, hose, and orifice is supposedly identical. Yet, when I tee them all together and connect to one of the TB ports the column heights aren't equal -- there is variation between columns, not a lot but it's there and it's repeatable.
Theoretically, the orifice diameter should not effect the average column height, only the amount of "pulsing" up and down that occurs, since the mercury blocks any actual vacuum air flow. Why you observe a difference should not be caused by the orifices. You may have some tiny vacuum leaks somewhere else in the system.
I guess I have been guilty of the "Well MY bike doesn't do that so it must not really happen" syndrome. It is fairly common, not just here but on every forum I have ever seen. Dad's '07 has always been silky smooth at every speed above idle. Once I installed the PC-V it got smooth everywhere. Therefore I ASSUMED...
Some people also say they do not
feel the lean surge that occurs in (almost) every fuel injected motorcycle (and many late model carby ones too) at a steady cruise. That doesn't mean that the surge isn't there, or that it can't be improved on, just that
they can't feel it.
This vibration thing is the same kind of thing. Based on my own experience, I find it very hard to believe that there is any FJR that could run for years and years without ever needing to have the throttle bodies adjusted, or that if you did adjust them this way that the vibration wouldn't be reduced. OTOH, the
need to balance them is based solely on the amount of vibration you feel. So, if the rider can't feel the vibration then I guess it wouldn't need to be adjusted.
A TBS and a RDCUATBS are two entirely different maintenance/adjustment animals.
Take credit for perfecting a throttle plate sync (you deserve it), but don't pretend a lowly, bog-standard air-screw adjustment is gonna perform miracles getting rid of cruise-RPM vibes.
Meh... just semantics.
They are both procedures for adjusting the throttle body's vacuum balance with the same end goals of reducing engine vibration. The RDCUA is the same
basic Unauthorized Adjustment procedure that has been bantered about ad infinitum since the FJR was first released. The original "UA" version just had you watching the vacuum as you cranked the throttle open and then trying to adjust out that misbalance. The
only thing I have added is a way to do it at a steady state, without all the revving, by first closing down all 4 air screws and then doing it at (near) idle. I've said many times that adjusting just the air screws is a waste of time (and money if you are paying for it). But there are some people that feel
any TBS is a waste of time and not at all necessary. Just read some of the posts above.
I'm not looking to take
credit for anything. In fact, the whole concept of doing the RDCUA TBS (with the air screws closed) was the outcome of a conversation here on the forum with another New England member (whose name I forget now and who has long since moved on) from up in Old Town, Maine. It was all
his idea. I just did the testing and documenting (and then a whole bunch of successful using) of the procedure.
