Unusual vibration problem

[Montalbano]

Trying to solve a problem with vibration that has just started.

Had a standard Indian GP 200 rebuilt with a classic 225 rapido kit and 48mm clubman a few months ago.

Just covered a thousand miles with it carefully running it in without problems, until the other day when excessive vibration started. At first I just thought road surface as it was an unfamiliar road but by the time I got home (around 30 mile) hands and ars! completely numb.

Fitted new silent blocks as they seemed a little worn but no difference.

Whipped of the flywheel dust cover to check the end of the crank and it looks to be running true.

Thinking back, just before I first noticed the vibration I heard what I thought was a stone just been thrown up! no idea whether that is relevant or not!

I've not driven it hard or thrashed it yet! so it has not been under any excessive stress.

Any ideas on what to look at next would be very much appreciated.

Thanks

[IaninDorset]

You're feeling it in the back rather than the front?

Could a stone got jammed in the rear shock? Or something metal or a cable outer thrumming against the rear end of the frame?