compression help DASA low 1 cylinder.

[Chris V]

what would be some possible causes on low compression in one cylinder. front cylinder 170psi / rear cylinder 130psi.. running a dasa 863 PV. Second season on motor realized something may have wrong when it was hard to start...

 

[Freakrider]

Blown o-ring in head or you scored a piston, stop cranking it and pull head off first while carefully inspecting oring for damage.

 

[Chris V]

Blown o-ring in head or you scored a piston, stop cranking it and pull head off first while carefully inspecting oring for damage.

ok thank you very much

 

[Chris V]

what causes the o-rings to blow?

 

[D-Roc]

overheating and a sleeve drop

 

[Freakrider]

what causes the o-rings to blow?

Normal very slight dome movement in the head shell. This is why some builders use a thin layer of 1211 sealant where the domes meet the head shell, to help curtail movement and wear.