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Notes
These are some additional notes of interest in regard to the Maxim-X thermostat and related repairs.
 FAIL OPEN - LIKELY
Although the original Yamaha thermostat for the Maxim-X isn't a fail-open unit, that's exactly what it tends to do. I haven't heard from any Maxim-X owners or service technicians that the original thermostat will fail shut and cause over heating. However, I have heard from many people that the typical failure mode is in the open position, making it difficult to get the Maxim-X up to operating temperature. If your Maxim-X seems to run too cold at all times, it may be an indication that your thermostat needs replacing.
BAD CONNECTIONS - MAYBE
Although I haven't been able to verify it for myself, I've been told once or twice that apparent low operating temperatures might be imaginary and possibly the result of an inaccurate temerpature gauge reading. Some Maxim-X owners have reported that cooling system debris buildup can cause the temperature sending unit (Yamaha Part# 11H-83591-00-00) to report inaccurately and some others have made similar comments about a poor electrical connection on the thernoswitch assembly (Yamaha Part# 2EL-82560-00-00). Both parts are found in the vacinity of the thermostat housing under the gas tank, directly behind the ignition coils. Often there is no cooling problem at all and a simple cleaning of the temperature sensor and electrical connections will restore normal operation.
MODIFIED FAN CONTROLS
It's not uncommon for the Maxim-X to run hot (right into the red) on a hot summer day in stop & go traffic. Although the X is liquid cooled, it appears that Yamaha chose to have the cooling fan kick in at the very moment that operating temperature reached its maximum. It doesn't appear to be a problem, however, most Maxim-X owners  would seem to prefer to have cooling begin a little sooner. I've heard from one Maxim-X owner who made some resistance changes of his own to cause the cooling fan to regularly engage a little sooner. I've heard from another Maxim-X owner in the Netherlands who installed a digital temperature control switch made by a company called Eliwell. Apparently it's necessary to fabricate something that makes it possible to measure engine temperature from the outside of a coolant pipe, but in the end, you can dial in any temperature you like to trigger the cooling fan. Most Maxim-X owners who are determined to change cooling fan operation will simply install a manual fan switch somewhere inconspicuous. If your Maxim-X runs too hot for your liking, you may want to try one of these methods of engaging the cooling fan... but long before that, you should verify that the fan is actually functional - they often aren't.
HI-FLOW NECESSARY
The Maxim-X generally runs pretty cool under normal operation. In fact, the gauge doesn't often reach "high noon" - regular operating temperature. That had me wondering whether or not to replace the original thermostat with a "regular flow" model rather than the "high flow" model it came with. However, as already mentioned, the engine can build up a lot of heat on hot summer days in stop & go traffic and on sustained high speed runs. A high flow thermostat seems to be absolutely necessary to improve cooling under those extreme circumstances. It's not recommended to replace the original part with a thermostat that has a smaller flow aperture.
NO VERIFIED REPLACEMENT FOR RUBBER SEAL
When servicing the thermostat, it's wise to keep the original rubber seal and treat it gently. The seal is a cross between a gasket and an o-ring in that it acts as a seal between the upper and lower halves of the thermostat housing but the seal has a groove on the inside perimeter which stretches over the edge of the thermostat. As yet, I haven't been able to source an identical replacement and Yamaha doesn't sell the seal alone. To replace it with an identical one, you'd have to buy the entire thermostat assembly from Yamaha for about CAD$45 (Yamaha Part# 3GM-12410-00-00). However, in April of 2006, I found what appears to be a viable replacement seal at Part Source. Although the seal has a slightly larger diameter, a ROL W08361-001 "Water Outlet Gasket" from Part Source will apparently work (although I haven't officially verified it yet). Some other part numbers that would identify the same gasket from different suppliers are CTC 17-4279-6, FP-35001 and VICT C24117TC. Remember, I have only purchased and measured one of these replacement seals. I have not yet had occasion to install one in a Maxim-X thermostat housing, therefore I cannot verify that the proposed replacement seal will be appropriate. I recommend treating the original rubber seal in a way that would allow you to reuse it but if replacing it is unavoidable this is the best alternative I've found. If anyone has installed the aforementioned replacement seal in their Maxim-X successfully, I welcome the feedback.
MOTORAD - THE IRONY
One final, ironic observation - after searching high and low for a suitable alternative to the original Yamaha thermostat, I converged on a thermostat made by a company called Motorad. What's ironic is that the German word for motorcycle is Motorrad. Don't that beat all.
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