Head gasket

[Pilot_LC]

forgot to add the part where i ask for help if anyone knows where to get one

[Calum]

Several options

Can you not skim the head and barrel and remove the imperfections, then space the barrel with two bottom gaskets?

Can you not get yourself a reusable copper head gaaket. They used to be all the range a few years ago.

You could always contact an engineering firm like PJME to machine an o-ring into your setup to bypass the imperfections.

https://www.pjme.co.uk/acatalog/Yamaha-DT125R-Head-Gasket-O-Ring--5866.html

[Pilot_LC]

i sadly cant skim the head because i dont have the machines myself and in my country its a rather ellusive and expensive thing
where could i find the copper gasket and will it make the compression go down?
and about the o-ring can i let the machining be done at a lathe here by the dimensions on the pjme site and if i switch to o-ring its just the o-ring or is it the o-ring+headgasket

PS sorry for my spelling english isnt my main language
and thanks for the help!

[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.