zxr250 cooling problems

hey there people
i have just recenly purchased a 1992 zxr250
it has a overheating problem/ cooling problem
the bike tends to run fine however once the speed goes over 80km/h the temp gauge keeps going up till about the half way markat which point i over ride the std fan switch and turn the fan on manually
i have replaced the fan switch but this hasnt solved the problem i was wondering if any 1 else has experiance this problem or may have any sugestions that may fix.
im thinking of replacing the radiator, fan, thermostat, and hoses to see if this solves it

thanks in advance

justin

I had similar problems with my Spada- turned out to be the thermo switch AND the radiator cap- maybe you just need a new cap as well- $15 or so for an aftermarket one....

Try in this order.

* Flush radiator out with an alkaline radiator flush, i usually put it in, ride the bike for while. I did mine for 30 mins for a first treatment (as i didnt think it was bad, i was wrong) which didnt do the job for mine, so i did it again for about 4-5 hours of riding to totally flush the bastard out. then disconenct all rad hoses and flush every internal area out with a hose at rather high pressure, reassemble.

* Take thermostat out and see if it "opens" at 100'c, replace if farked.

*Replace cap (never hurts to do this anyway).

i reckon the same as above.

coolant or cap or both

pull the thermostat out,
there's no need for one in brisbane.

effectively what happens is, the thermostat blocks the water from flowing to the radiator until the engine warms up to a certain temp, then it opens to let the cooling process happen.

QLD isn't cold enough to need the thermostat to close so the engine can heat up. only poms need it. i took mine out and it fixed the exact same problem. replace it if u want, but i didn't see the need.

thanks for replys guys
i thnk i will be a busy boy in the weekend... is the thermostat located on the top of the motor under the tank?
do u find on winter mornings the motor will run to cool with out the thermostator no worries

cheers

Don't chuck the thermostat- if you do the bike will never be at the correct operating temperature and premature wear will result! If it is stuffed you can ride around temporarily without it, but make sure you replace it!

check the clamps on the pipes that goto the radiator (and conect to engin)

IF you dont know the history of the bike and certain that it has ALWAYS had coolant in it check to see (when the thermo DOES open) that the water is actually "flowing past" the cap.

I have seen alloy water pump vanes "disolve" to nothing when they have had tap water run in the radiator..... its spinning but there are no "fins" to pump the water....

Damn you would have to be unlucky but....

Don't chuck the thermostat- if you do the bike will never be at the correct operating temperature and premature wear will result! If it is stuffed you can ride around temporarily without it, but make sure you replace it!

doesn't a thermostat just open and close at a certain temp?

doesn't a thermostat just open and close at a certain temp?

Yup they do, but the closed phase is very important- you want the engine to warm up as quickly as possible- most of your engine wear occurs just after starting, while the bike warms up- the thermostat allows the bike to warm up quickly, as it effectively cuts the radiator out of the equation whilst the bike warms up. When cooling is required, the thermostat opens, allowing the radiator into the cooling circuit. The thermostat has an important job to do in conjunction with the radiator- keep the temperature within a pre determined range, giving the best performance and best wear characteristics- if you remove the thermostat you can shorten the life of your engine considerably.
FWIW air cooled engines are generally built with looser tolerances because they have a wider temperature range to deal with- (so they can expand and contract more) they don't have the benefit of a liquid cooling system to keep the temperature more constant.

fair enough,
just wouldn't have thought it'd be an issue in our climate. i would've thought oil and regular servicing would be more important.

fair enough,
just wouldn't have thought it'd be an issue in our climate. i would've thought oil and regular servicing would be more important.

I've taken the thermo out of most of our cars when they fail...CBF'd replacing it and makes SFA difference in a car....although a bike might make more difference...having only a liter or 2 of coolant and all...speaking of which I need to replace the coolant in both car and bike...bugger...anyone know if water restrictions allow the use of a hose for purposes of flushing out engines?

fair enough,
just wouldn't have thought it'd be an issue in our climate. i would've thought oil and regular servicing would be more important.

I've taken the thermo out of most of our cars when they fail...CBF'd replacing it and makes SFA difference in a car....although a bike might make more difference...having only a liter or 2 of coolant and all...speaking of which I need to replace the coolant in both car and bike...bugger...anyone know if water restrictions allow the use of a hose for purposes of flushing out engines?

why are u putting water in the engin ? isnt that were oil goes ?

why are u putting water in the engin ? isnt that were oil goes ?

It is? oh shit brb...