https://youtu.be/lDod3DgGva4
So I picked up this scooter from the lds for $10. Had a stuck piston. Good use for wd-40. After contemplating how to equalize the pressures in the tank, flywheel, and exhaust, I finally found the perfect use for my poor quality second stage. Some rubber hose, two part putty stick, and troublesome gopro, I was ready for a swim. I found out at about 20 feet the breathing air is dense enough it runs like its super charged. It gets a real deep throaty sounding exhaust and runs stronger. But if you turn it off below ten feet, you can't pull the starter hard enough to restart. You have to go back to the surface. I vented the ignition chamber to the air intake, and the gas tank to the exhaust chamber. Ive had it to 40 feet, but I'm afraid of busting a piston or rod if I go deeper. It doesnt seem verry worried about conserving air, though. 100cf usualy gives me over an hour in that lake. Aquascooter cuts it back to about twenty minutes.