Death wobble

I'll show you mine if you show me yours. This is my earlier (sold last year) Kawasaki 750). Hard tail, wobbled a bit between 0 and 20 mph, no big issue to stop it, for some reason worse from cold - could be stiff tyre?
The one below it is my current one Yam Vmax full power, IRS back end, doesn't wobble at all, but is heavy on the 'bars, so I'm going to make a new front end for it.
If you want help you have to do your bit - I asked you what speed yours wobbles at? Strike this - I re-read your original post. Wobbling up to 30 mph is higher than normal though.
Now, you could also try to upload a couple of pics - let's see what the front and back looks like - some home made trikes are nothing but badly welded death traps, not suggesting yours is but they really do vary.
And @XJ550H asked you weather this problem developed or did you buy it like this - I suspect someone sold you a failed build, but confirmation please?
A leading link front end is an expensive fix, and you should try all options first, including a damper, even a quallity version will be a loads cheaper alternative.

 

Fair enough.