overheat

hi all
took my project out today and first time i have ridden it really more than a few hundred yards.
was alarmed to see the needle touching the hot line in 2 miles.
went home and left it idling. got hotter so switched off.
rad water hot. overflow bottle stone cold?
fan cuts in ok
does anyone have a cooling system diagram?
really hoping the water pump is not faulty.
possible air lock?

Perhaps a silly question, is the radiator fully filled with coolant? Did you tip the bike to get rid of air in the system? Sounds like there is air between the radiator top and the reservoir, and they don't connect. That is assuming the pump and thermostat are working fine.

Sounds like the classic problem of having not "Burped" the air completely out of the radiator. As Stan points out - If you remove the rad.-cap, the coolant should be up into the neck. The Procedure is easy and clearly outlined in the manual. Once confirmed that the air has been purged and you still have an over heating problem then the thermostat should be checked/replaced. If the problem persists then the issue could be with the water-pump and/or with a plugged-up radiator.

Yeah guys water is right to the top in rad.
I have not done any work yet so last owner maybe filled it without purging. Will look at this tommorow.
Thanks

Update
Water is to top of rad
Overflow expansion box full
If motor is run with fan disconnected the temp guage goes to red hot then cap opens and expansion box starts to fill. With fan connected temp guage goes to red and fan cuts in. Temp guage stays red does not go down. Fan cuts in and out but mostly in !!
Just worried about running so hot.
Is there availability of a cooler sender unit for the fan?

Just linking this for your consideration.

www.kz1300.com/index.php/forum/electrica...90-fan-switch-option