Dablue1

Did you increase your idle speed after the bike was warm?
Are you getting any coolant being released into the reservoir? This is a clear indication of overheating.
Did you buy the temp sensor new?
What kind of spark plugs do you have installed? The wrong type plug has been known to cause overheating issues.
In what condition is the gauge cluster in? There is a possibility the temp gauge is misreading and needs replacement. You may very well be below the threshold and all other components are working properly, especially if you are riding in cooler temps.

If you are still concerned about overheating, here are some other things to consider.

Overheating:

Firing incorrect:
Spark plug dirty, broken, or maladjusted
Spark plug incorrect
IC Igniter trouble

Fuel/air mixture incorrect:

Main jet clogged or wrong size
Fuel level in carburetor float bowl too low
Carburetor holder loose
Air cleaner poorly sealed, or missing
Air cleaner duct poorly sealed
Air cleaner clogged

Compression high:
Carbon built up in combustion chamber

Engine load faulty:
Clutch slipping
Engine oil level too high
Engine oil viscosity too high
Drive train trouble
Brake dragging

Lubrication inadequate:
Engine oil level too low
Engine oil poor quality or incorrect

Coolant incorrect:
Coolant level too low
Coolant deteriorated

Cooling system component incorrect:
Radiator fin damaged
Thermostat trouble
Radiator cap trouble
Radiator fan switch trouble
Fan relay trouble
Fan motor broken
Fan blade damaged
Water pump not turning
Water pump impeller damaged

Actonite

Here is the schematic for your bike, check it out electrically first then grab a thermometer and check the actual temperature of the engine because you may just be getting a false reading on the gauge. http://faq.ninja250.org/images/a/a4/...matic_-_R4.pdf

marino6385

this may sound like a stupid question but im new to all this. Where on the engine should i check the temp with a thermometer?

Actonite

No stupid questions, you won't know if you don't ask. You can check the temperature at the same place as where the temperature sensor is inserted or take the rad cap off and insert a thermometer into the coolant and then warm up your bike. If you take it off once it is hot you might get burned. Do you have a multimeter? You can check to see if the fan switch is actually closing. With the multi meter you can also measure the resistance of the tempurature sensor to see if it is working properly - Thermistors