Conjecture either way regarding a transient spike of the temperature gauge. Thermostats can stick slightly which resolves and doesn't reoccur.
As for the lack of by-pass on the Versys, my friend Fast Eddie Copeman has #1 & #2 (sold to the public) ThermoBob kits on his two Versys. The desirability of a by-pass system is distinct from the excursions which may be seen on the temperature gauge. My point was similar to yours, I think, in that the gauge does tend to encourage speculation on the part of the uninformed.
On the other side of that coin, the binary aspect of warning lights means that a trend towards a problem is not anticipated and the degree (literally in this case) of the problem cannot be examined from the bike's instruments. I'm a fan of temperature gauges but do accept that putting numbers onto them is generally counter productive for makers.
A by-pass system is almost universal on automotive and larger applications, as well as higher end bikes. I'm completely adrift to understand why Kawi would knuckle under for the modest cost of a pair of drilled holes and a hose. Clearly, by-pass and higher temperature thermostat is the superior strategy.
If someone is motivated to install a T-bob out of movement of the temperature gauge alone, that is limited justification but still does achieve the same advantages.
Running the engine under cold conditions is not conducive to efficiency or longer engine life. The KLR engine sees a huge difference in temperature between top and bottom of cylinder as well as a reported 40 F difference between the temperatures at the temperature sender and the thermostat. Anyone who has studied the coolant passages has almost certainly felt the same shock over the last difference as have I.
The engine was clearly designed to operate at above 210 F. One can easily prove this by virtue that the fan switch operates at 210 F so the engine clearances had to be designed for that operating range. The temperature routinely goes much higher under hot and slow conditions with no harm so someone can speculate a number for the high temperature design limit. 235? 250? I don't know either but one doesn't have to even crack an engineering text to support the design temperature must by up there.
So, let's use 220 F as the number. Low but to illustrate: that is 60 F lower than the thermostat and almost certainly at least 100 F below the temperature of the bottom of the cylinder. Reports have shown the cylinder temperature can bridge 140 F from top to bottom and my primitive instruments seem only to support that.
Put a bore gauge into some KLR cylinders torqued to a head and watch what happens when the head is placed into near boiling water. Taper and out of round make excursions as one knows must happen.
A straw poll of T-bob users reported that oil consumption and fuel mileage improved with the install.
The misquoted: "If ignorance is bliss, 't'is folly to be wise." makes the point, IMO. People ignore the "If". It is seldom beneficial to be ignorant if one is able to act on the information., IME.
I think this illustrates that people often do the right thing for the wrong justification.
I'd put a by-pass system onto a Versys as the second modification, right after a better engine guard. Having done by-pass and higher temperature 'stat to something like a dozen KLR650's, am hoping to do a couple of KLX250's after the summer.
A transient spike from the temperature gauge would more likely be electrical, rather than thermal, in nature, IMHO.
Just completed a 2000-mile ride on a Versys, a Kawasaki 650 cc motorcycle, but with about twice the power of a KLR650. Kawasaki got smart; no temperature gauge on the Versys, only a dashboard warning (not unlike an "idiot light") of overheating. No radiator bypass either, AFAIK
Unprovable theory: Fewer Themo-Bobs would have been produced, had KLR650s similarly been equipped with idiot lights, vs. temperature gauges.