What about wheel bearing grease, can that be used?
It can, but is not reccomended....by owners. That is part of the problem , as Kawasaki, and others for that matter , actualy do use bearing grease at the assembly line for these parts. The high loads and tempatures they endure however is not condusive to bearing grease. There are "high temp" greases that do seem to fair well, but just about every forum that deals with some model of a shaft drive bike reccomends the use of a High Moly content grease (of at leat 60%)
If you read the Vulcan Verses here there are a few other options than Honda Moly 60, which is the one most readily available.
A quick little story here. When I took my FJR in for its 600 mile mandatory servie, I asked them to check the drive splines for the proper grease. (yes, it is not just Vulcans) The shop service tech said it was not part of the schedualed service...and that I would have to pay for the labor involved for them to do so. I countered with this proposal...if the splines were in fact lubed properly with the correct molly content grease, I would pay the labor costs...if however the splines were not lubed properly, then it would be considered a warrenty issue and I would should not have to pay for them doing something they should have done correctly to begin with.
When I went to pick up my bike, there was no charge for the spline lube.
The tech said although there was evidence of grease on the splines, it was a below the suggested mininum amount and was not a molly content grease. This on a $14,000 bike with only 600 miles on it. You'd think they'd have their "act together" too.......
If you have not at least looked at your splines...do so now before riding season begins...no matter how old your bike is or what the previous owner told you...