over heating

[Rick.O]

does anyone know why a race bike would over heat? Its ok for 3-4 laps and then it goes into the red or onto the H.

[RedexRobB]

I take it the coolant was done recently(ish) and its topped up, so possibly head gasket or the thermostat, or maybe even fuel settings if its running lean.

Check the thermostat first, theres a test in the manual for it, costs you nothing. If thats ok then a compression test might be in order.

[Rick.O]

Thanks, coolant has been changed (water only, no aditives)and thermostat has been removed so it looks like it may be the head gasket then?

[zimm]

Thanks, coolant has been changed (water only, no aditives)and thermostat has been removed so it looks like it may be the head gasket then?

fraid so


edit :

is it dumping water ?
do you still have a fan connected ? if so does it come on ?

it "could" just be a dodgy temp gauge circuit if you're really lucky, check all the wiring for shorts, and test the gauge as per the manual.

[Rick.O]

its chucking water out like mad. Ive pressure tested the rad and it overflows at 1 bar ish like it should do but when its on the bike it over pressurises when the guage gets to about half way. the fan has been removed.
I have tried 2 different rads and another water pump, last year I had to tape the rad up to keep it warm.

[zimm]

head gasket for sure then, get it changed and it'll be fine