When your engine overheats
(1) is the rad fan rotating fast?
(2) is the whole rad getting hot?
(3) is the cooling system pressurised (you can check this by squeezing the rubber tubing)?
You could try testing or replacing the thermostat and rad cap.
Also, make sure the rad cap is seating correctly and there is no build up of crud under it.
In addition to flushing the rad internally, ensure the external rad matrix is not blocked with rust and debris.
While investigating, providing the bike ambient temperature never falls below zero degrees C, it is quite safe to use tap water for a short period, but once the system is fixed you will obviously need to fill with the recommended cooling fluid mix.
(1) is the rad fan rotating fast?
(2) is the whole rad getting hot?
(3) is the cooling system pressurised (you can check this by squeezing the rubber tubing)?
You could try testing or replacing the thermostat and rad cap.
Also, make sure the rad cap is seating correctly and there is no build up of crud under it.
In addition to flushing the rad internally, ensure the external rad matrix is not blocked with rust and debris.
While investigating, providing the bike ambient temperature never falls below zero degrees C, it is quite safe to use tap water for a short period, but once the system is fixed you will obviously need to fill with the recommended cooling fluid mix.