Overheating ZX7-R; need advice.

[Johnik]

Hey everyone,

I have an overheating issue with my 1998 zx7r and need your help. When ever I am stuck at a light, after about 1 minute, I can see the temp gauage rising slowly. By the time I'm moving again she will hit around half then after riding at 80 km/h the temp drops back down to normal, no dramas. In extreme situations I have had the guage read 3/4 and over!! However this was on a 35 degree day and I was stuck in city traffic.

The thermo fan comes on when the temp gauge reads half and runs untill the temp drops back down, so its not that. The coolant is as green as the bike and it appears to be flowing as I can see it when I take off the radiator cap so it aint that either. There is plenty of coolant in the bottle and I noticed today it overflowed a bit I think that was my fault .

Which leads me to think that its a possible airlock somewhere in the system which is causing the temps to rise when there isnt enough air flow. Has anyone else had such problems on their bike and fixed them by bleeding the system correctly? If so could someone please post a step by step list of how to do it. I'm not 100% on the method of bleeding a motorcycle cooling system so any advice would be GREATLY appriciated.

Thanks in advance everyone

[SocialSecurity]

When ever I am stuck at a light, after about 1 minute, I can see the temp gauage rising slowly. By the time I'm moving again she will hit around half then after riding at 80 km/h the temp drops back down to normal, no dramas. In extreme situations I have had the guage read 3/4 and over!! However this was on a 35 degree day and I was stuck in city traffic.

there is nothing wrong with your bike.


check the service manual for proper bleeding procedure. but if you open the radiator cap and the water is up to the brim, then its most likely fine.

[Johnik]

Why do you think I am asking this question here mate? (me no havi de manual)Maybe my post needs more detail

Lets say I'm at the light for 3 minutes +/-, my bike would be well on its way to hitting 3/4 temp. Now lets say this light was 5 minutes, at this stage I'd be contemplating turning the bike off. Surely someone has some "useful" advice...

[jpbikeboy]

My zxr750 does the same thing. it always has. My mates zx7 does go up to half and sometimes beyond aswell. There is a bleed valve on your waterpump to bleed air out of the system. Also check your thermostat. It may have been removed, or it may be faulty.

[Johnik]

Ok JP, kick ass, thanks for the info. Should the bike be at operating temp before bleeding it ?

[mike-s]

absolutely, if you want to risk getting hot coolant on yourself!
Bleed it cold, then take it for a spin, bleed it again till its just water coming out, should be ok the first time you do it.

[SocialSecurity]

Why do you think I am asking this question here mate? (me no havi de manual)Maybe my post needs more detail

Terribly sorry, have a little look see here for a service manual

but basically any bike will behave much the same.... as long as the fan comes on and it doesnt get any hotter than about 4/5 of the way thru the 'normal' zone its ok.... but a radiator flush, new thermostat etc wont hurt... also pays to check the condition of the radiator fins, they tend to cop a bit if the bike is ever ridden at high speed use a flat blade screw driver to straighten the fins if lots of them are bent over


if its anything like the ZX9R then the bleeding screw isnt really necessary to fill the system

[Johnik]

Ok sweet, thanks Mike and Social (from worlds worst post to worlds best ) That helps me out a bit, I'll get cracking on that and see if it helps the situation.

Oh and on that link you posted Social, it says there is a zx7r manual but it doesnt seem to be listed in the directories Be good to have that, I been searching for one that I can download for ageeesss. Anyhow, thanks again peeps!