I recently addressed a "tank slapper" wobble. Here's what I learnt.
Like yours only an issue without any pressure on the bars, but mine was different to yours in that:
1) It was stable at most speeds but occurred consistently and immediately between 40 and 45 mph.
2) It would immediately (at these speeds) wobble very fast, say 4 oscillations per second (none of the starting slow then building in speed you describe)
As soon as speed dropped below 40 mph nice and stable again subject to road surface.
I took it to my local Yam dealer to get checked out and asked that they check all the bearings etc for safety. They told me:
1) It wasn't unsafe (I mean due to failed bearings etc, not that the wobble wasn't unsafe)
2) It's usually caused by the top box rack (even without box attached) or uneven front tyre wear (although there are many other causes, but those are most common)
3) They could change the front tyre (it was due anyway) and slightly loosen steering head taper bearing to see if it helped (but no guarantees)
4) Bearings were fine (visual inspection of from wheel, others checked for play)
Having had the front tyre changed it's a lot better. Not gone completely, but minimal enough that it's not a practical problem. Nice to have had the bike checked safety wise too.
I suggest that:
1) your wobble doesn't sound too bad given that it starts quite slowly
2) But if it makes you uncomfortable get it checked out and try to fix it
Start by looking closely at your front tyre. How many miles has it done, and how is the wear?
Do you have a rack?
Andy
Like yours only an issue without any pressure on the bars, but mine was different to yours in that:
1) It was stable at most speeds but occurred consistently and immediately between 40 and 45 mph.
2) It would immediately (at these speeds) wobble very fast, say 4 oscillations per second (none of the starting slow then building in speed you describe)
As soon as speed dropped below 40 mph nice and stable again subject to road surface.
I took it to my local Yam dealer to get checked out and asked that they check all the bearings etc for safety. They told me:
1) It wasn't unsafe (I mean due to failed bearings etc, not that the wobble wasn't unsafe)
2) It's usually caused by the top box rack (even without box attached) or uneven front tyre wear (although there are many other causes, but those are most common)
3) They could change the front tyre (it was due anyway) and slightly loosen steering head taper bearing to see if it helped (but no guarantees)
4) Bearings were fine (visual inspection of from wheel, others checked for play)
Having had the front tyre changed it's a lot better. Not gone completely, but minimal enough that it's not a practical problem. Nice to have had the bike checked safety wise too.
I suggest that:
1) your wobble doesn't sound too bad given that it starts quite slowly
2) But if it makes you uncomfortable get it checked out and try to fix it
Start by looking closely at your front tyre. How many miles has it done, and how is the wear?
Do you have a rack?
Andy