Engine won't crank with spark plugs in

[alpacalunch]

I got a 1988 GT from a friend. PWC has not been used for some years. Previous owner says it has never been flipped. There was water in the engine compartment when I got it, could be accumulated rain and snow, was not properly covered. Starter bendix was rusted, cleaned it up and now works fine. Sprayed some preservative in cylinders, engine turns over when plugs are out, some gunk came out initially. Turned it over repeatedly until no more gunk came out. But when I put the plugs back in, it tries to turn over, but won't. Battery is strong. Any thoughts? I don't know too much about Rotax engines. Thanks

 

[Klipsh]

I got a 1988 GT from a friend. PWC has not been used for some years. Previous owner says it has never been flipped. There was water in the engine compartment when I got it, could be accumulated rain and snow, was not properly covered. Starter bendix was rusted, cleaned it up and now works fine. Sprayed some preservative in cylinders, engine turns over when plugs are out, some gunk came out initially. Turned it over repeatedly until no more gunk came out. But when I put the plugs back in, it tries to turn over, but won't. Battery is strong. Any thoughts? I don't know too much about Rotax engines. Thanks

Maybe I'm overlooking something in the post but the starter? No compression is created with an open head so when a weak starter tries to turn over upwards of 120psi of compression it could struggle.

 

[alpacalunch]

Maybe I'm overlooking something in the post but the starter? No compression is created with an open head so when a weak starter tries to turn over upwards of 120psi of compression it could struggle.

Good thinking. The starter spun well when I took it out, but maybe I need to take it out again and disassemble and clean up the commutator. Not a job I want to do again, but thanks for the suggestion.