I think you have a problem with the oil you chose to use as afterun. The instructions that came with the engine expressly warn about using a after run oil that has no petroleum based oils or solvents in it.

I would say replace all the seals in the motor. While its apart clean all the parts in denatured alcohol.

The regulator diaphram is probably the main culprit but it could be a bad o-ring or seal anywhere in the engine.

Marvel Mystery oil is a petroleum based oil. Just put a piece of silcone fuel line in it for a few day. It will eat it and make is soft and mushy....this is what happens to the silicone o-rings in your engine.


It might be best to send it in to YS Part and Service and have them look the motors over.



Troy Newman
Team YS Performance