# 2 stroke issue



## jmckeon (Feb 21, 2009)

Here is a quesstion when it gets below 20 degress my 2 stroke polaris dont waanna start. Had to do heater tarp trick other night on bay when in single digits aboout 10 mins with heater on fired right up. It starts amd runs fine above 20 degrees. And once it starts in colder westher it runs fine just dont wanna start elxtric start or pull start? Has been driving me nuts. Rebuilt the carb. Adjusted the choke cable. Run mix 50 to 1 for gas. And new air filter.


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## Z-Rider (Feb 9, 2014)

As temps drop 2 strokes require jetting changes to the carb(s). Just one reason sled manufacturers have moved to 4 strokes and added EFI to their remaining 2 strokes


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## MossyHorns (Apr 14, 2011)

Z-Rider said:


> As temps drop 2 strokes require jetting changes to the carb(s). Just one reason sled manufacturers have moved to 4 strokes and added EFI to their remaining 2 strokes


I would agree that his jetting has to be too lean. All of the fan cooled 2 stroke motors made today have carberators. 4 strokes and EFI have been pushed into the maket by the EPA.


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## bowhunter426 (Oct 20, 2010)

Z-Rider said:


> As temps drop 2 strokes require jetting changes to the carb(s). Just one reason sled manufacturers have moved to 4 strokes and added EFI to their remaining 2 strokes


Unlikely to be a jetting issue preventing starting. I would be more inclined to believe it is an electrical issue or compression brought on by cold weather. Next time it wont start check spark and do a compression test


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## bigcountrysg (Oct 9, 2006)

Just need to clean the carb. 

I bet it has not been cleaned ever in it's life while being used.


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## plugger (Aug 8, 2001)

bigcountrysg said:


> Just need to clean the carb.
> 
> I bet it has not been cleaned ever in it's life while being used.


 You don't think they cleaned the carb when they rebuilt it?


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## Uncle Boopoo (Sep 15, 2008)

bowhunter426 said:


> Unlikely to be a jetting issue preventing starting. I would be more inclined to believe it is an electrical issue or compression brought on by cold weather. Next time it wont start check spark and do a compression test


The amount of fuel an engine needs to run properly is directly related to the volume AND temperature of the air coming into the engine. Colder temps require more fuel and warmer temps are the opposite. Fuel injected engines can adjust automatically to temperature and altitude changes, carbureted engines cannot.

In this case, the op needs to richen (add more fuel) to the idle circuit of his carburetor. Sometimes cleaning the carb can help if it hasn’t been done in a while, but on a “clean” carb, changing the jetting is the only fix.



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## Chasin Tales (Jan 20, 2006)

Curiousity question-are you running rec gas or something with ethanol? Would this affect below freezing starts?


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## tito (Apr 27, 2012)

Put a primer on to give it shot of gas. You might have misadjusted the choke. If your depressing the throttle it by passes the choke on start. Wont add any fuel til the revs come up. Turn your air screw in full close to 1/4 when it gets cold like that


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## Burksee (Jan 15, 2003)

1) Did you check for spark when it wont start below 20 degrees? If its not getting spark it could be the stator, CDI box or the coil that's effected by the temperature.
2) If its got good spark typically even the most cold blooded of engines will start when choked. I'd be looking at the carb and choke, if its got a Mikuni on it the choke plunger may be seized in the bore or to much free play in the cable to lift it high enough of its seat to do it any good. Also, most chokes will have two settings, the first one is when you flip the lever so its pointing straight out, push it over a little more to its second setting that,s takes it to the edge of the choke lever. I've shown a lot of folks this and that's all it took to fix.
3) When you cleaned the carb did you check to make sure you could spray carb cleaner thru all the passages, ports and jets? I've seen many a jet or passage still plugged or restricted after being "rebuilt". Get yourself a role of the really small diameter green florists wire to fish thru the passages and jets, its not expensive and quickly pays for it self.


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## boomer_x7 (Dec 19, 2008)

When was the last time the fuel lines were changed. Could be a hairline crack that open just enough when the lines shrink from temp drop.... Next time it happens, check for spark. If you have spark at the plug gap(when’s the last time the plug was changed?) the go through the fuel system. Re clean carb change fuel lines and filter. Also just because the carb was cleaned and rebuilt doesn’t mean it didn’t suck another piece of crap in. 


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## YZman (Mar 4, 2004)

2 stroke carbs typically use an "enriching circuit" and not a conventional choke plate. Make sure lever is pulling plunger up high enough. A lot of times, when carb is cleaned, people neglect to make sure brass tube and/or casting in float bowl, from bottom where plunger seats in main carb body is cleared, along with passages to bottom of float bowl. Also note that choke circuit becomes less effective as throttle is opened up, allowing less "draw" through choke circuit.


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