with a stock muffler on a sp 500 and it stalled out in water over the muffler would it suck it back in and ruin the motor??

 

Water could get into the engine if your exhaust valve is left open when the engine dies. But if you keep the RPM's up and the intake above water, it shouldn't die. I use low range while in deep water to keep the engine speed up and lots of air moving out the exhaust pipe.

As far as ruining the engine, that's a different thread. Do some research. Use the search function at the top of this page.

Dave

 

Happened to me several times on my Kaw bayou 300. Have not had the problem with my SP 500(yet - hopefully never do) Good advice from the post above. Keep those RPMs up while swimming. If you do start to drown it out then kill the engine before it sucks water back in it.