Experience with welding Titanium frame?
I think this question has gone a while without an answer because it's a little unclear what you want to do... do you want to do it yourself? Or by 'experience with welding' do you mean 'experience with having welded'? 

Either way, I don't have an answer for you, because I don't have direct experience welding titanium, nor do I know any welders in NJ, but I do have some tips for you:

There's nothing wrong with being a big guy and riding bikes--trust me, I know many people who do it. However, it's important to realize here that most of the higher-end bikes you've ridden haven't been designed with you in mind at all. They're designed for the cyclist who weighs twice as many pounds as he is inches tall, because that's where the market is.

And sure, titanium is technically a stronger metal than steel, but yet again, even your titanium bike is designed for the same person your steel bikes have been designed for.

Here's my suggestion: Before you spend another $100 with a welder, think about this: for the approximate price of an average new titanium frame, you could have a custom frame made from steel, but with you and your size in mind: oversized tubing, reinforced lugs, maybe even a double top-tube*. The bike would be specifically designed for you (it's been done before) and would not fail like your previous experiences.

There's lots of framebuilders in Philadelphia and New York--it can't hurt to ask around. Hope that helps!   

* An aside: I actually think they look pretty cool. I'm a really tall guy, and I'm looking forward to the day when I can buy a custom-made bike that actually needs one. =]



Image Source.