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Zx6R B1H Overheating?


675Jim

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Need a bit of help with my new-to-me B1H. It runs fine when ridden on the road. Even on a long run or in city traffic. But show it a track and it overheats in about 5 laps. So far I've given it a good looking at. Then removed the thermostat. And fitted a shiny new radiator cap. But to no avail. I can's see any leaks, and the coolant level stays constant. Fan is working correctly.

I'm pretty much out of ideas. Any advice much appreciated. I'm hoping it's not an expensive head gaskety-type problem...........

Ta

Jim

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Have you bled the system? There is a bleed bolt on front of cylinder head near the exhaust headers on left side and one on the waterpump housing.

I would bleed system or flush out and put fresh coolant/water in.

Also the rad could be blocked up.

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When you say it overheats, what's it doing? Spewing coolant everywhere or just on the temperature gauge?

Seems odd that it's fine on the road and in traffic etc - you'd think it would be the other way round.

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did you remove the thermostat for a reason or just to see if it was working ?

if your running it without a stat the water might not be circulating the jacket at the right speed to cool the motor effectively

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Faulty water pump

Rad fins blocked

Faulty Temp switch

There are kits you can buy to test to see if the HG has gone.. When was it last serviced?

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When you say it overheats, what's it doing? Spewing coolant everywhere or just on the temperature gauge?

Seems odd that it's fine on the road and in traffic etc - you'd think it would be the other way round.

Temp creeps up to 118-ish and then flashes HIGH on the LCD display. If I pull in when I notice it, it will then spew coolant out. If I ease off and change up at 12K rpm rather than redlining it in every gear it will cool down and run at a reasonable temp. It does seem odd; you'd think screaming along at high speed would provide plenty of air-cooling effect.......

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did you remove the thermostat for a reason or just to see if it was working ?

if your running it without a stat the water might not be circulating the jacket at the right speed to cool the motor effectively

Took the stat out to eliminate it as a possible cause. It ran slightly cooler without but still overheats when caned.

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The motor obviously doesn't like running at higher temps for some reason. It spews out the coolant when you come back in because there's no/less air flowing through the rad to cool it down after a session, it will warm up the coolant fast.

I take it you have checked the oil for any emulsification? Could indicate head gasket issue.

When does this happen? As in was it happening before the weather went cold and 'orrible or is a very recent problem? Lastly are you running proper coolant or de-ionised water?

Run the bike up in the garage for 5-10 mins and place your hand on the radiator and check for cool/warm patches. That could indicate there's air in the system or it is clogged up - if so, with what is it clogged? I only say do this to eliminate it if it is an issue. If it is clogged up, then something has caused it to become clogged, which may be the underlying problem.

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Temp creeps up to 118-ish and then flashes HIGH on the LCD display. If I pull in when I notice it, it will then spew coolant out. If I ease off and change up at 12K rpm rather than redlining it in every gear it will cool down and run at a reasonable temp. It does seem odd; you'd think screaming along at high speed would provide plenty of air-cooling effect.......

Id say water pump..at a guess.. But try back flushing the rad/system as well.. Also make sure the rad fins are not blocked.

Edit to say:- Try using distilled water & some water wetter as this will drop the temp a bit.Normal tap water has higher boiling temp iirc.

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I'll check the water pump. Rad looks clean. I've only just had the bike so for all I know it could've been the reason the guy was selling it.......... I've changed the coolant for Motul Mocool, which came highly recommended, and flushed the system through, but still no improvement.

Oil looks good, and no smell of exhaust gas when I take the rad cap off, so I'm still thinking head gasket unlikely.

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Is it running the standard exhaust / air filter? - running lean can / will cause the engine to run hot.

Have you checked around the rad cap opening for any damage? - fitting a new cap won't help if the filler neck is damaged.

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I had a similar problem with my zx636 motor C1H, i'd recently rebuilt it and got the coolant bottle pipes mixed up, basically one pipe comes from the rad top and goes to the head, and the other comes from the rad top and goes to the underside of the coolant bottle, anyway, gave similar symptoms, took ages to realise what i'd done, i've not read the entire thread, and not sure if your model is similar, i suspect so though, but if you've had the rad/bottle, pipes off etc, check they are back in the correct order, my 2cents, all the best.

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I changed the coolant and flushed the system when I removed the thermostat. Will try bleeding it again though. Cheers for the suggestion.

so have you bled the system it could be an airlock

you havnt altered the height of the rad for any reason have you? just checking......

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I had a similar problem with my zx636 motor C1H, i'd recently rebuilt it and got the coolant bottle pipes mixed up, basically one pipe comes from the rad top and goes to the head, and the other comes from the rad top and goes to the underside of the coolant bottle, anyway, gave similar symptoms, took ages to realise what i'd done, i've not read the entire thread, and not sure if your model is similar, i suspect so though, but if you've had the rad/bottle, pipes off etc, check they are back in the correct order, my 2cents, all the best.

also did similar with my r1 except it spewed coolant everytime you revved it

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mine used to gradually get hotter as a trackday went on, i actually ended up changing what was a brand new head gasket, and only realised during the second head rebuild!, 50 quid head gasket down the toilet for nothing, still learning the hard way has always been a fav for me!!

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Think we have a winner. It seems the standard rad has been replaced with one off a different bike. Was hoping I could get away with a cheap Chinese one to put it right, but Mattbloke's mate would clearly advise otherwise. Will get on eBay. New genuine ones are a shit load of cash.

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think its bikebandit.com where you can reverse part look up and see if other models fit, I know Z thou of same year is the same mudguard and rear panels

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