I think that in regards to these mosfet voltage regulators: the best advice is to buy from a reputable source. Buying a generic mosfet voltage regulator off of Ebay will probably result in getting something that is inferior to the stock KLR unit. There have also been some posts about finding a used VRR off of certain motorcycles--usually fuel injected or otherwise computerized. These bikes have less tolerance for voltage fluctuations, and have more sophisticated VRRs. Again, you might get lucky, or maybe not.
My experience has been with the Shindengen FH020 which I recommended. It is a quality part, which is readily available, and reasonably priced. When I start my 01 KLR, the voltage is 14.1-14.2 and it never varies regardless of the engine speed. No cooking the battery at high speeds, or discharging at low speeds. It is larger than the stock unit, but all that I needed to do was drill a couple of new holes. If you just want something that works, then this would probably be one way to go. The FH020 will handle the loads on something like a full dress Harley, so it should last forever on a KLR.
The original poster mentioned that his voltage was varying, which is a known issue on a KLR. Most people do not have a voltage readout, and just do not know that it is happening. That is why most of the electrical upgrades include a better voltage regulator.
Cheers,
Doug Walker
I think your original mistake was in not involving someone else in the previous work. This would easily allowed shifting of the blame. 
Kidding aside, glad to hear that you found the problem. FWIW, and not related to this thread directly, remelting solder drives off the lighter metal from the alloy which makes the material harder to melt, potentially overheating the nearby structures. It also seems that repeated remelting or over heating of some of the new low/no-lead solder can create a poor quality joint. I'm wondering if anyone has noticed this effect? It's a problem with silver-soldering and seems like it affects some "lead solders".