Speedmaster high speed vibration
I need some help. When riding over 50 mph the bike has a weird vibration. To describe it, it feels like go over a series of small bumps. The "bumps" last for about 1 or 2 seconds then it stops for about 3 or 4 seconds and does it again. The road is smooth asphalt, with no visible imperfections.
The bike is a 2006 Speedmaster with 2k miles. The bike was purchased over the winter as a project. At the time of purchase, the dealer indicated there was nothing wrong with the bike.
Since purchase I have swapped out the cast wheels with America lace wheels. The wheels where taken apart and rims powder coated. The wheels were then laced and trued by a 20+ year pro.
In the process of swapping the wheels, I reused the cush drive, final sprocket and carrier, axle's and axle spacers from the speedmaster setup.
The front tire was replaced first with a Metzler ME880 (for about 60 miles) and then with a Avon Venom. The back tire is the original Metzler ME880 with 2k miles.
Wheels and Tires were balanced at the local bike shop on a machine. The front took an ounce and the rear was one and a half once.
Since having the tires balanced I removed the front and had it re-trued and balanced by hand. The hand balance method resulted in no weights being added (and some griping about the machine balance quality by the same 20+ year pro).
Progressive springs have been added to the fork tubes. The compressed part of the springs are at the top (to keep the fluid level the same).
The front bearings have been replaced.
The wheels have been aligned back to front and rechecked.
The steering head bearing load has been adjusted (may be a smidgen to tight now - but adjusting had no effect)
The brake rotors have been checked for run-out. The front is on the edge of needing replaced at .012".
The chain has been adjusted and rechecked.
Wheel weights have been removed from the rear tire, with no-effect.
Need some help here fellas, what could this be?
'06 SM -current ride (Short TORS, K&N PODS, 140 x 42 x Thruxton needles 3 shim, 1.75 turns)
'07 BMW R1200R, '04 TBA, '79 HD FXD, '71 850 Norton Commando, '78 Suzuki GS550, '72 Hodaka Wombat