Head gasket

[Pilot_LC]

okay found a solution that i completly forgot a large piece of glass + fine wet sandpaper and it should to the trick the cylinder itself is completly fine

[Calum]

@Pilot_LC Yeah, I wrote a blog on doing it here: https://dt125r.co.uk/post/23

It's only a gentle skim, it won't cure completely warped heads.

Be sure to the deck of the barrel too.

[Pilot_LC]

did the process the original gap was about 0,1mm got it down to zero put it together with a new standard gasket and it holds! also it has more compression now then ever before and i can feel that it has more power

[Calum]

@pilot_lc That's amazing! Fingers crossed that's it now then.

[Pilot_LC]

yeah so it ran for 600km with no problem then started randomly getting really hot and spewing coolant out just like before so now i had to bring it home with a trailer (again) and ill disassemble the head tomorrow to see what the problem is now.

[Calum]

@Pilot_LC 600km, are you sure you used a genuine head gasket and not the cheap white ones.

And it was definitely fitted in the right orientation.

[Pilot_LC]

@Calum yes i used a athena head gasket and its 100% in the right orientation.
also what saams to be wierd is that its spewing out coolant from the overflow tank but there is no pressure in the system when you remove the radiator cap even when its really hot. It also doesn't seem to be burning coolant

[Calum]

As I say, one issue is the radiator cap spring looses tension so try replacing that.

I just use a cheap Chinese one on my DTR with a temperature sensor in it and it's been sound.

Another problem could be the thermostat as given up, maybe it's locked closed so it's not regulating temperature correctly.

[Pilot_LC]

okay but how would those explain the significant loss of coolant through the overflow tank?

[Calum]

@Pilot_LC Ideal Gas Law - PV=nRT. Pressure of a system is directly proportional to the temperature of that system. So if the thermostat is stuck, then the temperature goes up and therefore the pressure. The radiator cap bleeds this pressure to the overflow tank. Ergo explains loss of coolant.