ZX9R C1 running warm

[NinjaMoses]

Have searched around a bit online but most of the info Ive found is relevant to older B models. I have a 98 ZX9R C1. It has fairly high km on it but the engine still runs peachy. A few weeks ago she started running a bit warmer then usual. Just wondering if someone can point me in the right direction to check first.

Moving along quickly she still sits at 3 bars temp like normal without any problems at all. Slow it down to the 60km/h range for more then a few minutes and it creeps up to 4 bars and stays there. Stop at the traffic lights however and within a few minutes she has a major dummy spit and before long the fan kicks in, and the coolant overflow bottle fills up and boils over.

There isn't oil in the coolant or vice versa so I'm guessing its not a headgasket etc.
From what I have read online in general it sounds like the radiator cap and the thermostat are the first things that need looking at which I will probably do tomorrow.

Does anyone know of specific issues with the C1 models which might be the cause?
Or does anyone have any other suggestions?

How easy/time consuming is it to swap the thermostat and how much is a replacement one?

thanks in advance,
Kris

[NinjaMoses]

Probably should have mentioned its also boiled over once or twice before it even hits 5 bars (or the fan kicking in).
After a bit more reading it sounds like a faulty radiator cap will cause the coolant to boil over at a much lower temperature, so I will check that first tomorrow and if that doesnt fix it will move on from there.

[Rossi]

My money is going on the thermostat being faulty
Easy enough to check when you ghet the bugger out

for the simple reason that it's a lot harder to get at than the radiator cap

[Strika]

Sounds like a little leak somewhere!

[Strika]

Check the Rad cap before anything else. If it were the Thermostat which wasn't opening, then it would most likely cook even while moving as it would restrict water flow. It sounds like either a head gasket gone, or a leak in the rad system somewhere.

[NinjaMoses]

Hrmmf thermostats and radiator caps are much more expensive then I was expecting.
First place I called quoted me ~$65 for the thermostat and ~$53 for the radiator cap.

Just waiting for a callback from a second store, hopefully they are slightly cheaper at least.

[mick_dundee]

Welcome to the world of motorbikes, where the same radiator cap you can get for $5 at Repco will cost you $50 from a motorbike stealership...

[jl4049]

Take the cap into repco or similar and see if one from a modern jap car will fit, chances are you will find one for 10 bucks.

[98ninja]

had two zx9rs 94 and a 98
both had this problem.
new thermostat fixed it both times

[MiG]

My GPX250 is doing the same thing but I've tested my thermostat and it seems to be opening at the right temperature. Nothing is fishy, except for the temperature being higher than it used to be. Fan switch works, thermostat works, no cross contamination in oil or coolant. WTF. This started happening after a coolant change, the old one was possibly quite old.

[mike-s]

just a coolant change, or did you flush the whole damned thing out thoroughly including taking the hoses off the radiator and taking a garden hose to it? it could possibly be something with the impeller fans (broken/corroded impeller = lower water flow) or shit in the block. If anything i would say new coolant would run, well, cooler.

[edit]thinking about it, couldnt it be that the new coolant absorbs heat better than the old, so theres less residual heat in the metal and more in the water, thusly it appears that the engines running hotter, but the metal is now just running cooler?[/edit]

[Saki]

Mine does the same thing at times, but weather has been slightly warmer lately so i will put it to that! Colder days she runs never higher than 3 bars.... so perhaps weather ?? Maybe not listen to these other guys!!

[NinjaMoses]

Well I got both the radiator cap and thermostat earlier this week. Fitted the radiator cap since thats a 10 second job but haven't got around to doing the thermostat yet. Will do a complete flush of the system at the same time when I fit it. Weather has been nice and cool the last week so I have no idea if the radiator cap has made a difference, but I will swap the thermostat out anyway just for good measure.

On an unrelated note, just put on a 520 chain & sprocket kit (-1 on the front). Ahhhh talk about absolute heaven compared to the well worn 530 stuff on it previously. Buttery smooth goodness. Feels like its gained about 20 horses

[dave#3]

Well I got both the radiator cap and thermostat earlier this week. Fitted the radiator cap since thats a 10 second job but haven't got around to doing the thermostat yet. Will do a complete flush of the system at the same time when I fit it. Weather has been nice and cool the last week so I have no idea if the radiator cap has made a difference, but I will swap the thermostat out anyway just for good measure.

On an unrelated note, just put on a 520 chain & sprocket kit (-1 on the front). Ahhhh talk about absolute heaven compared to the well worn 530 stuff on it previously. Buttery smooth goodness. Feels like its gained about 20 horses

It's funny you say that, I put a 520 chain and sprockets on mine last week too, also down 1 tooth at the front. I was actually pretty nonplussed by it - it revs higher for a given road speed in a given gear, obviously, but instead of riding the horespower wave I just found I was shifting up another gear. Bloody 9's and their torquey mid-range are just too flexible Trying to fins 7th on my short freeway blat was fun

[NinjaMoses]

It's funny you say that, I put a 520 chain and sprockets on mine last week too, also down 1 tooth at the front. I was actually pretty nonplussed by it

I think in my case it was probably more because the previous chain & sprockets were absolutely rooted and were robbing big power. Even if I had gone +3 on the front I reckon it still would have felt a million times better.