hey all. I have a 94 sport400 that starts overheating after about 2 hours of riding. The fan is running, and it continues to ruun into the overflow tank, and spew out the top. I haven't been able to find any leaks, and the water seemd to be circulating through the radiator. Any other ideas?

thanks in advance..

 

a new coolant change will help,70-30 mixture of coolant to get max protection,but you can try a "colder" spark plug before doing anything...it is normal the fan is running when hot,but if the red overheating light is there it is time to stop and maybe too late for engine damage...

 

Not sure if you know there's a air-bleed screw on the stock heads, or on the billet units you have to loosen the clamp on the coolant hose to burp the air out. If you haven't already, seriously clean out the fins by spraying garden hose pressure water from the rear of the radiator. Careful using a pressure washer here, because it can fold over fins. Don't know if you've changed your coolant on a regular basis, but the internals of your radiator could be clogged also. You can try running Red Line's Water Wetter, mixed 4oz/gallon of distilled water...only use distilled water anytime you mix any coolant, anti-freeze, or Water Wetter.
Normally it's mud, or trapped air.

Good Luck,
Ken

 

when you say "colder" plug, ,are you talking about gapping? Or physically different psark plug? I am running the stock plug now.

 

cwloring: If your cooling system seems fine, check for a busted head gasket. Mine did the same thing after riding my 400 for about an hour. I never could figure out why it was doing this, but after poking around, I had a busted head gasket. It wasn't bad enough to cause noticeable steaming out the exhaust, but it was a big enough leak to cause me to start losing fluid, then it started to over heat. One way to check is to read the spark plug or look down inside the cylinder and see if the piston is cleaner then normal.

 

Cwloring, yes there is a coolant screw in the top right side of the head,open that up till coolant comes out to bleed the system of air.Mike told me by not doing that a hot spot is created in the head.

 

gapping of the plug,no i'm talking about colder point spark plug,if you're using the stock one from what i remember it is a 8,try a 9 even a 10 if weather is pretty hot,as the number grow the "colder" is the plug...

 

NGK plugs: BR7ES Hot Plug.

BR8ES in the Middle.

BR9ES Colder.

BR10ES Coldest.


how "Hot" means how powerful the spark is.

If the plug thing doesn't help, I would reccomend and oil Injector block off kit, you will definately get the correct amount of oil to the engine instead of hoping that your injector is pumping correct. but you have to mix it.

 

as long as everyone is talking about plugs..... what is the difference between a resistor and a regular plug???

 

blaa bla..

spark plugs don't have stronger sparks from one number to the next.

the plug temp rating is based on the plugs ability to cool it's self.
the ribbed porcelin part it the main part that helps it cool.

hotter plugs stay clen better, and colder plugs foul more easily.

hotter plugs may cause preignition though (a hot spot the ignites with out a spark) wich can cause piston damage.

but you must also have a plug that runs hot enough to burn off deposits or it will foul out.

Just run a 8, thats what comes stock.

a resistor plug has a fine power'd conducting core that cancels out some unwanted frequencys of the ignition system, wich may interfere with radio reception, or electrical componets in the vehicle.

things to check would be plug color, to make sure your not running lean.
this may due to partial clogging of the carb, or sucking air past the crank seals or an intake leak.

check all the components of your cooling sytem including the radiator, fan, temp sensor, thermostat and radiator cap (inspect this one carfully for proper sealing)

the temp sensor and thermostat can be dropped in a cup of hot water to check (220 degrees).

then make sure you properly purge the cooling system of air, and run about 70 percent water, and 30 percent antifreeze, or water wetter.

Also tilting the quad about 3 foot up in the rear, then 3 foot up in the front after completely filling the cooling system should get rid of any air pockets in the system.