125-200cc please sumone help me....

hiya
please can sumone help me.
i have a husqvarna sms125,08 reg..
the other day it started to bog and not drive properly at all...???????
today i took my head off an the powervalves were covered in black oil..????????
the piston was black too.?????
but there was no scores n the ring was ok...iv now cleaned it all...
it also looks like a tiny bit of coolant has been getting into the head through the top gasket???? would this cause the bogging an the piston an powervalves to be so black..
as far as i know its standard (apart from it has a DEP back box)
and i think sumone has messed with the carburettor
the pin is set on the middle notch??? (is that to rich???)
mixture screw is 1.5 turns out.. ?????
can any help me plz.??

Was the weather colder then usual? A 2 stroke will run leaner in the colder months due to the denser air. I run my main jet bike a bit rich in the summer and can usually get away with dropping the clip one notch (richer) in the fall and raising it back up when it starts warming up in spring. Sometimes, depending on where the bog is, you can get away with adjusting the air screw.

Carbon will cause the oil on the powervalves to be black. If everything looks good I would check the head to make sure it isn't warped, replace the head gasket, clean the carb and try it again. If it is still getting a lean bog I would look into the jetting.

hiya mate.. thanks for replying to me..
im going to ive that a try and i will let u know how it goes...
im going to replace my gaskets n move the pin notch up 1...