Increase temperature at high speeds

[htorres2017]

I recently purchased a Yamaha 4 stroke 250, 2007 Year.
The motor operates well overall. At high speed, (35mph or 4500 rpms) I noticed the temperature increases and almost goes to overheating level. No alarms have been triggered. I reduced the speed and the temperature goes back to normal.
What kind I do to find out the problem. ?

Rgds

HT

[boscoe99]

I doubt you have a problem. The temperature bar can go to the far end of the scale, maybe even off the scale, and still be well below the over temperature point.

Motors without a closed cooling system will generally run hotter at high power than they will at low power.

If you are not hearing the alarm, you don't have a problem.

[99yam40]

You have not said when the water pump was replaced or the stats.
to make sure there is the proper water flow I would service them if they have not been or you do not know when they were serviced last.

the more fuel you burn in a closed device the more Heat(BTUs) are created and have to be removed.
just need to make sure the volume of water is what it was designed to flow.

There could be mineral build up in the passages restricting flow of water and heat to that water

[boscoe99]

The sensor on the OP's model is not indicatingwater temperature or anything related thereto. Well, maybe a bit but indirectly.

The sensor is measuring engine block temperature. Up high on the block.

[99yam40]

I am sure if there is not enough water flow the heat will be higher than normal on the metal also.

But like you said if it is normal to see the indications that he is seeing then no big deal.
I never hurts to make sure the motor has been serviced properly