1998 DT 150 Overheat Alarm

[smithpt]

I have two engines DT150 and DT 225, both 1998 with almost identical problems:

Hi, I have the alarm going off and subsequent rpm reduction after running above 3500 rpm. Have changed out pump, thermostats, poppet valve. Motor has been thoroughly flushed with Salt away. Heat gun reveals that the entire engine runs cool, except for a spot at the top of the port side cylinder bank around the temperature sensor which gets up above 240F while the rest of the engine is running at 150. This spot begins where the water jacket ends and extends to the crankcase and apparently sets off the alarm . I popped the head and the piston/cylinder look normal (all three look the same) and there are no clogs in the water passages, which are now quite clean. What else should I look at? thanks!

[Igonefishn]

If you are still having trouble with the temp, here is the fix that a local dealer found for me. I have a DT 225, 1998, that did the same thing. There is a resistor that fits in the line between the temp sending unit and the module. It fits inside the rubber boot where some of the other wiring connects. Don't know the part number, but he found the information in an old service bulletin from Suzuki. Hope this helps.