Got an 04 predator 50. It ran but wasn’t right. Compression really low And spark plug threads stripped so I rebuilt top end with Polaris parts and found a clean used Polaris head. Also replaced carb with aftermarket carb. finally got it all back together and it cranks fine but won’t turn over. So far:
-has spark,
-adjusted throttle to specs
-plug smells like gas so it’s getting some,maybe too much, definitely flooded after cranking so long.
-borrowing a compression tester tomorrow to see where the rebuild got me.

where should I start? It cranks like a champ, but honestly sounds the exact same cranking with or without the plug in so if say it’s not firing, but plug does spark when held to the frame
any adjustments needed on the carb? I installed 2 of these last year (other was on an 05) and the other runs like a champ so I believe I did it all correctly.

 

"it cranks fine but won’t turn over" Oxymoron, cranks means turns over.

If it really "sounds the exact same cranking with or without the plug in" then you have no compression, if you haven't got the tester yet, put your thumb over the plug hole, spin it on the starter and check if the compression blows your thumb off. If it has compression, fit a clean, dry plug and the old carb, as you said it did run on it before the rebuild, and see if it will start.

 

Compression tester reads 115, so I feel good about that. Fired up with a shot of starting fluid so I’m assuming fuel problem. Idled and ran for 30 minutes after that. Definitely running rich, a brand new plug black as can be after that 30 minutes and it’s smoking pretty badly. Tomorrow I’m draining what’s left of the fuel and oil and going premix in the tank as I planned on doing this anyway to avoid any oil pump problems.

about an hour after the 30 minute idle It fired up on one kick (battery died during all of the initial troubles), so I will reassess tomorrow