Snowmobile Fanatics banner
1 - 9 of 9 Posts

·
Registered
Joined
·
14 Posts
Discussion Starter · #1 ·
Ok here i go, you will get a kick out of this. Well to start off last year my Polaris 700 xc 1999 started to backfire wile riding it below 6000 rpm anything over no problem. Ok here is what we tried so far, 1st thing the carbs off and on/rebuilt so many times i lost count same with reeds even from switching them side to side same problem, on the mag side never the clutch side, ok next thing tried everything with the elcital from disconnecting every thing to the timing every thing was right on, next seals and gasket set for the hole engine at a dealer, next new kit in gas pump. Ok now is where i am with 2 dealers telling me I'm on my own they have no clue what the hell is wrong with it and me left trouble shooting it all my self with friends, now i come to see that running with the choke on runs like **** but no backfiring its getting weird that is where i am now help with anything in your mind or another trouble shoot try any info could solve the problem Thanks

well the engine just rebuilt to try to find the prob. the piston's were changed "pure Polaris" of course and the brake cleaner was used every where never sucked in any but changed the seals wile the engine was apart. the plugs are coming out light brown, the backfiring is only on one side, on the mag side only and its not the carbs because in switching the carbs from side to side the prob should follow it, it does not, stays on the mag side. running super gas in it nothing else added. Thanks

Well with the cdi box I had another one off another Polaris to try, put it on and did the same thing. I'm going to give the jet a different size on that side but the thing i don't understand is that the 2 spark plugs are coming out a nice light brown and it is backfiring out the exhaust.

I have been told by others that maybe my crank could be twisted but there is no strange vibration in the engine, but then again it only takes a little twist what are every one thoughts on that?
 

·
Registered
Joined
·
855 Posts
What needles are in there (stock?)
What Clip position are they in?
what are your air screws at ??
 

·
Registered
Joined
·
61 Posts
sounds like the Air/Fuel Mix is off...Rich it seems. figure out your air to fuel and i bet it goes away. spark plugs will be cardboard brown when its correct.
 

·
Registered
Joined
·
4,755 Posts
get the starting fluid out and check for air leaks ,.also are you running iso heet in you're gas ?
 

·
Registered
Joined
·
77 Posts
can you tell if it is backfiring throw just one cylinder? i had a part of a piston skirt brake off ( i think the intake side) of a piston and it was doing the same thing. just a thought. check your plugs?
 

·
Registered
Joined
·
482 Posts
use punctuation and multiple sentences. Sounds like its running rich and the excess fuel is exploding and backfiring. Use carb cleaner or brake kleen and start the motor, spray that crap all around the head and base gaskets, you'll know if its sucking it in.
 

·
Registered
Joined
·
2,729 Posts
If it is backfiring out the exhaust, check the float level and fuel inlet valve. May just be running too rich for conditions in that cylinder. Sounds stupid i know, but also check to make sure the jets are the correct sizes. Quite a few engines use different size jets on different cylinders.

If the backfiring is coming out of the carbs, you are running lean, and its time to check for leaks which i know you said you have already done.

If you are sure its not a fuel problem, check the spark plug caps (switch them from side to side) and see where that gets you. Next thing to do is to check into cdi and stator components
 

·
Registered
Joined
·
2,016 Posts
sounds to be a spark issue as you told you change the carb location. Maybe a loose connection or bad CDI. Did you try changing the plugs location and re-test it?
 

·
Registered
Joined
·
2,016 Posts
... and for personal knowledge, where the hell Howick is located ??? (I think you made the count of 4 for Quebec members! welcome aboard![8D])
 
1 - 9 of 9 Posts
Top