stihl.decompression valve

Issue as stated above. I installed a Big Bore kit on that saw and the valve pops every time I pull the cord now even with the spark plug disconnected. It's better with a chinese valve, but I still have to keep it pressed when starting. I even tried it with a new valve from Stihl, but it's just...

Not sure if this is the correct forum but if not - administrator please move topic. My STIHL MS 391 is a fabulous saw - once it is going but starting is now near impossible. I suspect it is the decompression valve sticking that is making the recoil starter too hard to pull. I found a...