Can anyone guess at what the problem could be on my dt 125 2002 I thought it would be the water pump seal so I've got a new one ready to fit but now I've found coolant in the exhaust so could this be just the head gasket or something worse I have a new head and base gasket just in case thanks for any help

Not sure about your exact bike but usually if you get the milky gunk in the engine it's a head gasket problem, just my guess you understand.

Ok mate hopefully just case of new gasket thanks

Coolant in the exhaust will be head gasket, possibly other symptoms will be overheating, bubbling in expansion tank, coolant dripping from frame, radiator level dropping.

Gunk in the gearbox will be water pump seal or possibly bike isnt being used for journeys long enough to get the engine hot

The rad level has been dropping and yh I haven't had it long and the bloke I got it off said he didn't use it much and I only use it for short journeys aswell so that could be the problem would the coolant in the exhaust make it smoke a lot for a bit and Also it doesn't idle very well and even when warm is hard to start without the choke

I'd change the head gasket for a proper yamaha one and change the oil in the gearbox...then monitor whats happening

Yh I will do you think could be dirt or gunk in the carb making it idle badly sorry to keep on but I'm not to sure

it might even be the water in the combustion chamber and loss of compression due to the leaking gasket, you should sort that out first to see if it improves

Yeah going to do it tomorrow hopefully it's ok after that getting annoyed with it now