www.zxrworld.co.uk

Just out of interest, how hot so your ZXR's run? Mine seems to slowly climb to max when doing anything under 50mph. The fan works, but only kicks in right at the top of the gauge (max). Is there a way to bring this down a bit? I'd prefer it to kick in earlier.

I remember it used to hate sitting still last summer so maybe I'm just paranoid. It hasn't exploded or anything yet and the fan is sufficient.
I thought I'd see what your guys say before going any further. After all, the ZXR is a bit of a strange animal...

might want to check your cooling system, mine never used to go over half way unless going for really hard thrash then getting stick at traffic lights ect in summer.

Yeah, I'm sure it never used to get this hot. I've not lost any coolant and the pipes running to and from the rad get hot so I know it's getting that far. I guess the rad might have a partial blockage or something. It works, just not as effectively as it should.

Cheers

Also, any idea if H and L models have different radiators?

My fan kicks in precisely at half way, and the bike never (hasn't yet in the cool weather) gets over the 2 bar mark and thats when im thrashing it hard. The fan occasionaly comes on in traffic but apart from that it stays cool!

My fan kicks in precisely at half way, and the bike never (hasn't yet in the cool weather) gets over the 2 bar mark and thats when im thrashing it hard. The fan occasionaly comes on in traffic but apart from that it stays cool!

mine used to do that, the previous owner fitted an overide switch for fan

turns out there was no antifreeze in system, me and baz drained it and it looked like a mud slide on his patio with rusty water!

after putting some antifreeze in it was fine, never overheated and fan kicked in around halfway

gem

half way up fan kicks in. - love that noise.
Stat never lets it above half way between the first two bars unless its summer and im stationary.

fan comes on at just over halfway line on my gauge, never overheats.

Cool ok, I'll take it apart later this week then. I checked the coolant and the levels are very high which leads me to believe there is a blockage somewhere. The coolant was changed when I bought it back in November and is still very clean.

To be honest, I'd rather have a leak than a blockage - much easier to find!

Will check out this fan switch too - mine's an import but I can't see that making a difference?

Anyway, thanks for the help.

how does too high coolant mean a blockage

as Gem said check the coolant for the right mixture, run a hose through the rad to make sure its clean and nothing blocking it, could be a faulty temp switch??

or thermostat

Did you put the coolant in yourself?

If the levels are high, where are they high - rad or the reservoir tank?

When you take the cap off the rad (when cold), does it hiss with pressure being released, or does it smell strongly of oil or anything that isn't coolant?

It could be air in your rad. From cold, shake the toad out of the bike, then take the cap off the radiator. Check the level of fluid in the rad and fill if necessary - ignore the reservoir for this test. Get hold of any rubber pipes you can and squeeze them around a bit to see if any bubbles come out (you need to do this A LOT with most bikes after you drain and refill the coolant!). Do this shaking and squeezing for a while or until all the bubbles are out, and then start the bike and do it a bit more.

As the bike heats upthe level in the rad will rise and start to spill over, so you can't do this part for very long, and don't do this starting with the bike hot!

Hopefully this will get it running fine again.

I'm pretty sure you should never be seeing over 2/3 temp - especially in this cold weather...

Mine's usually just under the 2nd mark, only ever goes higher when at lights etc and then the fan will kick in around half way.

I've been going on the reservoir/expansion bottle. It seems very high and should surely be distributed throughout the rad when the thermostat is open?
I heard a bubbling earlier after thrashing it and some coolant actually leaked out a hose situated near the reservoir. I assume this is some sort of overflow - like the valve cap on a car? Either way, I'm not sure if this is cause or effect - it shouldn't really be boiling.

To be honest, the mix seems very good - about 50/50 and very clean. It ran fine through hot weather and winter so whatever is wrong has occurred in the last week or so. I did wonder about air though - particularly as this would explain the expansion of fluid and the hissing(?)

I'm going to look into it when I get some free time over the weekend. I'll check the levels in the rad and pump some water through. If it all checks out, I'll fill her up again with new coolant. As for squashing the pipes to remove air, I'll give it a go but are there no bleed valves throughout the system?

I should've put this in the 'Having Problems?' section really, Sorry.
Thanks for all your suggestions though. I'll let you know how I get on.