Question about Polaris 2012 Sportsman Big Boss 6x6 800

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Engine wont start on my polaris big boss 500 6x6 after the piston and rings was replaced

Last month my motor would not turn over anymore, after i took the carb off i noticed a chunk of the piston was broken, so i took the head off and got a new piston and new rings, now i put it all back together and i have fuel and i have spark, but it wont start, i have compression cuase my finger blows out the hole when i try the old school compression test, its a 2 stroke motor, and yes when i placed the new piston in i made sure the hole markings was facing the correct way, WHAT DO I DO NOW!!!????!!

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First - Did you find ALL the pieces of the broken piston...if not...STOP and FIND them.. they are in the bottom of the engine WILL NOT live long if you have not gotten ALL the pieces--even the TINIEST ones out!! You mat have more damage than just a broken piston.. something caused it to break.. you may have cracked the crankcases...may have damaged the main bearing(YES) and/or damaged the crank bearing.. see if gas in leaking into the transmission oil.
There is an arrow on the piston that faces toward the EXHAUST port. If there are hole(s) in the piston, they go towards the INTAKE.
Do some more searching and repost the results for review!

Posted on May 30, 2017


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Posted on Jan 02, 2017

  • 3 Answers

SOURCE: i got a 1987 yz250 that wont start. we cleaned

check your float in the carb it could be off causing the bike to flood itself before you even get a chance to kick er over

Posted on Jul 15, 2009

  • 68 Answers

SOURCE: scooter wont start

carb could be clogged with trash even though fuel is gettin to carb the main jet could be blocked not letting fuel enter intake

Posted on Aug 02, 2009

  • 6966 Answers

SOURCE: My 50cc 2 stroke engine won't start, it has fuel

Hi and welcome to FixYa,

A couple of ideas:

  • fuel to the carbs - as you posted checks good;
  • fuel inside the carbs - loosen the drain screw at the bottom/bowl. Check for quality / quantity of fuel;
  • fuel into the combustion chamber - check the plug (would be wet).
For a no start 2 stroke engine with your described condition, a possibility to consider is too much / unburned 2T oil in the lower combustion chamber; remove sparkplug, air dry (or use compressed air).

Good luck and thank you for asking FixYa.

Posted on Sep 09, 2009

  • 79 Answers

SOURCE: 2 stroke engine not starting

Head or base gasket leak, spark is happening at the wrong time. Any of these will cause it to not run.

Posted on Oct 02, 2009

  • 35 Answers

SOURCE: 1981 suzuki gs550l wont start, rebuilt carbs, new plugs, new bat

did you adjust the iddle screws? Those black plugs need to be installed. Those carbs pull all gas threw the main jets. If you remove the black plug and look closely you will see a small tunnel going from that tube to the main jet tub. The fuel gets pulled threw that tiny hole from the main tube. (This also puzzled me the first time I saw one, don't worry, that was the first thing I thought of doing also, but since then, I have found tons of bikes and boats like this) I found mine runs best on 2-1/2 turns on the idle screws. Also try sincronizing you carbs, the cheep way to do this is by blocking them open slightly and checking the butterflies with a feeler gauge to see if they all open the same amount. I also found that sometimes it could be as simple as the choke slide not returning completely back to the proper position, this will cause the diaphrams to not operate properly. Good luck and hope I helped a little.

Posted on Oct 17, 2009

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