yes we have an oil pressure release valve. it's either at the oil filter or right by it. i can't remember. it supposed to release at 80psi i think. i've been blowing out a good amount of mist from the breather. i definitely checked it when i had the motor apart. i was told by a triumph mechanic that the way you test it is to see if it the valve moves freely and is not stuck. it tested ok but i've been second guessing because of the amount of blowout from the breather and if i really get on the throttle my oil pressure gauge pushes over 80. the purpose of the valve is so you won't blow out your seals. i've been having to fill my oil to the very bottom of the oil viewing glass to not get so much blowout.
this could all be perfectly normal. i don't know. here's a link to a video i made that shows the valve
here wonderin if someone knows how to test it in the bike. problem is, you have to split the cases to get to it.
