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everytime i seem to get the bvike runnning normally it goes tits up again !

just got it through the MOT re-test today (after replacing fw bearings and linkage bearings) decided to take it for a blast (as i booked the day off incase i had to do any more work to it!) - bike started to overheat again

why the bike is running "normally" it sits between the two first white marks on the heat guage and stays in their

no it is going out of the marks - so long as i stay at 40mph + no problems it builds to half way and stay about their - once i slow down to less than 40mph it starts to spike

dont think its head gasket as did readings a couple of weeks ago and they were all at 100psi min

just had to pull over as it was heading to the red - noticed the fan didnt kick in - so had to short it, and sit by the bike for 15 mins whilst it cooled down - then managed to get it home - one of my major concerns here is that fact that i replaced this switch for a brand new one just over a month ago, at teh cost of £35, which seemed to stop the spiking issue.

coolant is coming out of the overflow pipe - when i put my finger in the overflow tank is full to the brim of coolant too - the pipe from the rad fill point to the rad itself seemed very hot, whereas the one coming from the bottom of the rad (where the thrmo fan switch is) seemed lukewarm at best

any ideas - blocked radiator ?knackered water pump ? dont think its an airlock as bled the system last time i was having issues

any help as usual is appreciated - think im going to try a rad flush / coolant change - sound like the best option ???

yeah a rad flush and fresh coolant, you can buy rad flush too to give it a good clean. Whilst the coolant is out you can take the water pump out and check that too.

Head Gasket!

Myn did this. Was sucking air IN and blowing coolant OUT of the overflow.

Hopefully I am wrong, but thought I would share....

thanks guys, will try a flsuh

:wabby - dont think its HG as getting ok compression results

@ rob - any idea why the fan isnt kicking in ??? as its a new switch is likley that it is not kicking in as the fluid isnt getting to it to tell it its getting too hot ??? or would their be another reason for it not kicking it (it defo works as i shorted it without any issues)

is it possible to wire up the fan so that it is permanatly on, when the ignition is on ???

id say the fan isnt kicking in because that side of the rad isnt getting hot enough to put the fan on, does sound more like blocked rad to me rather than headgasket i think someone else on here had a similar problem and it was the rad that was blocked.coolant out the overflow is just the fluid on that side is getting hot and bubbling out the overflow.i would definatly go with flushing the rad first.

i think extonyg is right, with it only getting luke warm on one side, and by the sounds of it the side the thermistor is on, it being blocked is probably why its not kicking in.

You can wire a switch in, simply straight across the terminals like you would when you short it and they you can turn it on whenever you like Try the rad flush first tho, because leaving it to the fan alone probably isnt going to be enough to cool it and eventually cook your engine.

thanks guys - will try a flush tongiht then

is it done on the bike or is the rad removed to do it ???

have also read about a reverse flush - using a hose pipe, was going to try that first (flush it through normal way, flush it through from bottom section, then use the rad flsuh itself - anyone see any potential issues with that - just want to make sure it does the job !

one last thing - that i havent considered / checked - could the overheting issue be anything to do with a faulty thermostat ? or the the symptoms not suggest that ?

cheers

im pretty sure you can do it on the bike just using a hose pipe to blast it out. but i supose off the bike might be better/easier.
possible the thermostat could be faulty but i dont no where in relation to the side thats not getting hot is the thermostat.i think i would still go with the rad flush first, if you want to make sure you can remove the thermostat and put it in boiling water and you should be able to see it open you have to look closely though.

unplugged hose to water pump and water coolant came out no worries - drained system and filled with water, then flushed it as per the instructions I had.

bike was getting v hot again (almost up to the red) fan didnt kick in either - but their does not seem to be a blockage in the rad.

looking into the overflow tank their were bubbles in their, which i beleive suggests head gasket ???

oddly when i was refilling the system after the flush i had 1 litre coolant and 1 water, to top the system up (as the manual says it holds 2.3 litres) however I didnt even get all of the coolant in (maybe 3/4's of it) had the engine running and everything, but at most reckon i put a litre back into the system before it wouldnt take any more.

runnig the bike at idle for a few mins it got v hot again at which point i decided to call it a day

any more ideas ???

Sorry to say again but....

It really is pointed to HGF!

thanks wabby - bugger damn and blast - looks like a full engine rebuild then

so looks like it could be head gasket, despite getting good compression results - is there anything else at all that it could be, before i strip the engine ??? move into my new house next week, so will finally have a workshop instead of a driveway to work on, so will be getting the engine out and over hauling, debating doing the hole bike BUT weathers so good at teh moment don't want to really take it off the road for another couple of months

only other thing is the thermostat.

will give thermostat a test then !

ran it tonight on driveway - had it idling for 10 mins and it stayed within the 2 white marks, as it was on paddock, ran it for a couple of mins at 4k revs in 1st gear, and that was when the guage started to rise again - does this point more towards the thermostat or hg ?

other thing is, i only managed to get a litre of coolant into the system - would this pos mean that the water pump is knackered ? as its not pumping the coolant around the system, so that the other litre could be added ?

reds wrote:will give thermostat a test then !

ran it tonight on driveway - had it idling for 10 mins and it stayed within the 2 white marks, as it was on paddock, ran it for a couple of mins at 4k revs in 1st gear, and that was when the guage started to rise again - does this point more towards the thermostat or hg ?

other thing is, i only managed to get a litre of coolant into the system - would this pos mean that the water pump is knackered ? as its not pumping the coolant around the system, so that the other litre could be added ?

Hi

few things to check, water pump: rip it out and it turns freely an no fins are bent, Thermostat: chuck it in boiling water from the kettle and see if it opens. If all them are ok, take the bike to a garage and something whats called a "sniff" test. That'll then tell ya if the HG has popped.

Regards

Rich