front end decel head shake

If you set the rear end up so that your turn in is very quick, headshake on decel is probably going to happen. With it set high enough, you most likely will have to go with steering damper.

Since you havent mentioned installing anything that actually changes your rear ride height, I assume you either jacked your rear preload up to get the height, or raised your forks in the triple clamps, or some combination of the two.

Going back to baseline settings and recording your changes is time consuming to be sure, but its the best way to sneak up on the problem, since you have worked to eliminate all the bearing issues.

Sometimes its still a tire issue, as tiresome as that may sound heeheeee

Second suggestion: buy this book http://www.amazon.com/Sportbike-Suspension-Tuning-Andrew-Trevitt/dp/1893618455 read it cover to cover a number of times, apply it to your bike. You would be well advised to do this before dropping more cash on parts that may or may not solve your problem. This will work soooo much better for you than trying to get your answers from any number of forums.

Since you seem by your posts to be the kind of person that likes to figure it out for yourself, this is the way to go.

You will then be answering other people's questions. :thumbsup:

 

Sage advice I think. Sometimes it doesn't seem to matter how clearly you attempt to articulate yourself, something seems to get lost in the communication so that figuring it out for myself seems to be the only surefire way. Besides which I'm always working with someone I trust. Thanks for the info.

 

I don't think it's been asked. When did this head shake start? After you put the new tire on? Or the new tire was supposed to be a fix it thing for head shake?

 

I changed tires shortly after buying the bike. I didn't notice it on the initial test ride but became aware of it the next week or so. I figured it was probably a wheel balance problem that would go away after installing and balancing the new tires but as you can tell, it didn't. One mere note of interest, I just took it for another short ride and noticed that while it does it beginning over 40 and still does it at 65. it is the worst at about 55. I mean if I let of the throttle and take my hands off the bars, it feels like it would develop into one of those irretrievable death wobbles if I didn't grab the bars quickly. And I'm with you guys on the dampener. It seems like a properly set up machine should track straight even with my hands off.

 

Thought I found the problem. The forks were not set deep enough into the triple clamps, about 34mm instead of the called for 41mm. Corrected this with no difference noted. However, in all these test runs I've noticed that the decel wobble doesn't start until I'm going at least 50MPH and is the worst at about 55MPH. As I said before, it still does it at 65 but it's about the same as at 50.

 

Thoughts:

My VFRs have always seemed to create cupping on the front tire tread block edges, and sooner than I would guess after installing the tire. I guess these bikes carry a lot of weight on the front. I got so sick of it that I found a tire that has mostly circumferential tread grooves (running more around the tire instead of across it) and now the tire has no places to cup. See Link:
Michelin Pilot Road 2 Rear Tire - Street Bike - Motorcycle Superstore
I am not sure this can cause headshake, but it's good to eliminate one more possibility.

Changing the geometry by raising and lowering it can slightly affect things as stated here, but the original geometry of the bike is SO conservative that the changes you would be making aren't going to have a ton of effect on your issue or handling in general.
IOW, if you weigh the front of the bike before and after changes, it's not going to amount to much more than a similar difference of a big guy vs a little guy riding it, or a full vs empty tank of fuel. It will still have some effects on the steering feel, but you won't be changing things all that much. I actually did the math and have a spreadsheet showing the amount of angle the forks change for every 10mm drop on the front end. Here are some numbers:
VFR800 stock rake angle = 25.5 deg
Dropping front end 10mm will change rake by ~.8 deg, for a new rake of 24.7 deg
RC51 stock rake angle = 23.5
As you can see you can get a little benefit; but remember this isn't the only factor in quick steering, it is also dictated by the trail of the front contact patch, wheelbase, and the mass you are trying to push over.
Not saying NOT to drop front & lower rear (I did), or that you shouldn't try and see, just putting it into perspective.

That posted link to the steering head bearings issue, as far as I can tell pretty much boils down to temporarily overtightening the bearings to seat them properly. Not a bad idea I guess if you have a persistent problem, and maybe you (the O.P.) should try this. But the vast majority of bikes won't see this issue to begin with, as seating the bearings when replacing them and then tightening to specified torque should be all that is needed.

Did you replace the tire with a new one of the same exact kind? Maybe a whole different tire should be swapped on to see if it improves.
I agree that a damper will only be masking the problem. If you have exhausted all the mentioned possibilities, consider some unseen components may have worn out. Try rebuilding the forks, or having the frame inspected for cracks... It's best to see if you can get an expert to look at it in person, someone who has a notable bike shop (possibly other than a dealer). You could be chasing all kinds of stuff listening to us here!

 

might just be the tire.
I had slight wobble on my bike when hands off the bars w/ metzler M-1's and no issue w/ the M-3's - it depends on how the center grove is laid out.
also from the sounds of it, this should not be a issue that a stabilizer will be needed. That will be your call, I come from the 16" front wheel days, that when you took your hands off the bars the front would go just about lock to lock - but hell it still tracked straight.
What kind of front tire are you running??? also ck front to rear alignment.....

 

Check the balance yourself. Get the front tire off the ground (still on bike) and make sure there is no brake drag. Spin the tire slowly and see where it stops. Mark the bottom w/chalk or something. Spin the tire several more times slowly and note the bottom after stopped. If the mark stops in the same/general area(several inches) the tire is out of balance. The heavy spot will always be at the bottom. If the marked spot on the tire stops at different areas then it would seem to be balanced.

If your front tire was spun balanced it could be off then. Depends on the person doing it.

 

Just checked another good forum and the only thing they listed that really helped someone there track down a wobble was making sure the forks are set to the exact same height in the triples. Being off by 1.5mm seemed to mess this guy's handling up at certain speeds (~60mph). Once he got them even problem went away.

If they are ok, I suppose the same condition could be caused by differing resistance from the internals of the fork...