Cooling System On A 98 Techno

[dr nick]

Quite a long explanation..but bare with me.

When I was out riding yesterday ,after about 15-20 mins my bike started to sound really rough .At first I thought it may have been that the fan wasnt running and the bike was overheating,but the fan was on.

The engine was acting just like it does when the fan doesnt kick in on its own(which happens now and again) so I expected coolant to have come out the top of the expansion tank cap as it boiled over.But no coolant was visable and fan was running so I hit the kill button.

after a few minutes ,waiting for it to cool ,I started the bike up ...sounded ok....flicked the fan blade...didnt move..so assumed it was cos it had cooled down enough not to need it.After a few minutes of riding and of checking the fan ,it came on on its own .But after 15-20 minutes of very moderate riding again ...the same symptoms again...just like it was boiling over,but no coolant from the cap.

I hit the kill button again and waited for it to cool down before riding back to the car to go home.

Bit hard to explain the noise I was hearing....but...it sounded like a perfect 250 two stroke engine one minute....then quite quickly ...it sounded like a bag of spanners...knocking and generally sounding terrible .....just about the time it takes to boil the engine without the fan on.

When I checked it at home I emptied the coolant out to see how much I had in it,as I couldnt see any visable in the Ex` tank(I always check visually on the expansion tank before going out riding), I found that it had lost about 100mls of fluid but no sign of a leak from anywhere.I am going with the idea of a blown gasket causing the coolant loss (from 720 mls approx to 600mls).

But would losing 100 mls cause a problem like overheating so quickly ????.

What other checks can I do before stripping the cylinder off???

BTW..I`ve checked that the water pump works

Hope someone can enlighten me

Thanks in advance

Regards

N

[beta boy]

that happened on my bike it turns out that when i was changing the bolts on th water pump to anodized ones i undid the drain screw and let loads of coolant out because i could not get it back in in time so i toped it up with coolant againg but there was an airgap so it did not fill the hole system so when i got home there was none in the expansion tank i dont no if u did this but that is what i did that made my bike run crap

[rev`er]

I have experienced this once when out with wonderboy at our local practice bit, i was doing a small not steep hill climb in 3rd gear and when i arrived at the top i turned the bike of to wait for gavin and my bike started hissing, i always carry a philips screwdriver and allen keys on me just in case so i took of the tank cover and the coolant would be right full to the brim and was just about splilling out, so we waited 5mins and checked it again and the coolant had disappeared, nd the fan would not go on, so i left it for a while then decided to take a risk of the 10min journey home on the main road!!! When we got back gavins dad said you just need to top up the coolant so we did that and i mixed and extra 1500ml in a jar and took it back up with me the bike done the same thing again on the blast but the coolant wasnt as bad, so i topped it up and it done it again so once i had topped it up a few times after the bike boiling up it never happened again

Gavins dad said just keep filling it until it stops going down when the engine heats up, i did that and the fan works and i havent had any probs yet(fingers crossed)

hope this helps!!!

chris