Since you gave me more info during your visits here (and a few emails exchange) , I taught I would post this addition... please comment if my understanding is incorrect.On the first failure the temperature was high for two reasons: the original radiators were opaque to light when compared to the ones I replaced them with and I had left the left hand radiator fan unplugged on my spring maintenance routine. I did not realize that until I dismantled it later, and decided to replace them with some clean ones. When I replaced the motor, I ran it until both fans kicked in and the temperature never went above middle until it conked again 2500km later.
Bad cooling was certainly a contributor on the first failure but not so much on the second. I too wonder if there is something in the #2 cricuit that might be another source of the problem, hence my question to the group above: air leaks, partially plugged exhaust, bad injectors, blocked catalitic converter, other?
Besides the radiators, I think you need to specify a few other jobs / repair that have been done just before (or at same time) as you installed this new engine.
By a process of elimination, I believe these items are important to help pinpoint WHY this 2nd engine would fail again:
1) Your 4 injectors have been checked and cleaned by a reputable local injector shop a bit before this used engine was installed
2) I think you had replaced the Oxygen sensor - but I cannot recall when this was done timewise
IMPORTANT QUESTIONS... some I may have asked in our previous exchange, but I cannot recall all the details:
A) Do you have the Motronic version of your ECU ? This can be read using a GS911 -or- by removing the ECU to read the label on opposite face.
B Do you have a GS911 to check if the air-box temp sensor is working properly ? This is is important as you said you have removed the "cheater" device that was connected to it. You can make a rough check using a Multimeter OHMS function on the 2 male pins with connector removed:
- at 8 celcius (46 F): should read 3800 Ohms
- at 20 celcius (68 F): should read 2500 Ohms
- at 40 celcius (104 F): should read 1000 Ohms (you may use a hair dryer at "low heat" to warm up the tip)
C) have you ever tested the fuel-pump running pressure ? I have the needed gauge and adapters here but you need to have the right side fairing removed to connect "inline" between fuel tank quick connectors. On the K1200RS forum (and probably here too) we had at least 1 case where a pin hole / crack on the short hose connected to fuel-filter (inside tank) would cause a lean mixture. Total running pressure was not proper as per specs at 51 PSI.